PROPOSAL TITLE

Investigating Implementation Potentials of Turbo Roundabouts in Nevada

PRINCIPAL INVESTIGATORS

Kakan C Dey, PhD, PE (Principal Investigator)

Assistant Professor

Department of Civil and Environmental Engineering

West Virginia University

ESB 647, 1374 Evansdale Drive

Morgantown, West Virginia, 26506-6070

Phone: 304-293-9952, Email: kakan.dey@mail.wvu.edu

Bhaven Naik, PhD, PE, PTOE, RSP (Co-Principal Investigator)

Associate Professor

Department of Civil Engineering

Ohio University

226 Stocker Center, Athens, Ohio. 45701

Phone: 740 593 4151, Email: naik@ohio.edu

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TABLE OF CONTENTS

1. PROBLEM DESCRIPTION ................................................................................................... 1

2. BACKGROUND SUMMARY ............................................................................................... 1

3. PROPOSED RESEARCH ...................................................................................................... 3

Task 1. Hold project start-up meeting ........................................................................................ 4

Task 2. Review pertinent existing literature and best practices ................................................. 4

Task 3. Perform micro-simulation assessment .......................................................................... 4

Task 3.1: Site selection ........................................................................................................... 5

Task 3.2: Data collection at selected sites .............................................................................. 5

Task 3.3: Development of the calibrated models .................................................................... 5

Task 3.4: Simulation scenario development ........................................................................... 5

Task 3.5: Simulation and estimation of performance measures ............................................. 5

Task 4. Perform human factors (or driver experience) assessment ........................................... 6

Task 4.1. Submission of Institutional Review Board (IRB) approval .................................... 6

Task 4.2. Develop simulator scenarios ................................................................................... 7

Task 4.3. Participant recruitment ............................................................................................ 7

Task 4.4. Run test and experiment drives ............................................................................... 7

Task 5. Develop a selection procedure for turbo roundabouts ................................................. 7

Task 6. Develop educational resources and conduct effectiveness analysis ............................. 7

Task 7. Develop an implementation plan .................................................................................. 8

Task 8. Develop recommendations and final project report ...................................................... 8

Task 9. Conduct project management tasks ............................................................................... 8

4. URGENCY AND ANTICIPATED BENEFITS .................................................................... 8

5. IMPLEMENTATION PLAN ................................................................................................. 9

6. PROJECT SCHEDULE .......................................................................................................... 9

7. FACILITIES AND EXPERTISE ........................................................................................... 9

8. PROJECT CHAMPION, COORDINATION, AND INVOLVEMENT ............................. 10

9. BUDGET .............................................................................................................................. 11

10. APPENDIX A: EXTENDED LITERATURE REVIEW .................................................. 13

11. REFERENCES .................................................................................................................. 24

12. APPENDIX B: CVs ........................................................................................................... 27

Kakan Chandra Dey, PhD, PE .................................................................................................. 27

Bhaven Naik, PhD, PE, PTOE, RSP. ........................................................................................ 31

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1. PROBLEM DESCRIPTION

Multi-lane roundabouts have been used as a proven safety strategy for improving intersection safety by

eliminating or altering conflict types and reducing crash severity. Despite these advantages, multi-lane

roundabouts have several operational challenges such as driver confusion on proper lane choice decisions, striping

and signing issues, and concerns with the frequency of crashes (1). A relatively new form of roundabout referred

to as “turbo roundabout” has the potential to reduce the limitations encountered by multi-lane roundabouts. A

turbo roundabout's configuration can effectively guide drivers to reduce lane-change conflicts common in multi-

lane roundabouts (2). A turbo roundabout has ten conflict points compared to sixteen conflict points in a

traditional two-lane roundabout. In addition to safety benefits, a turbo roundabout could provide higher capacity

due to reduced conflict points (3). Moreover, a turbo roundabout can potentially be installed at locations where a

single-lane roundabout does not provide enough capacity, and a two-lane roundabout increases conflict. A turbo

roundabout was first designed and implemented in the Netherlands (4), where a before and after safety analysis

showed a 53% reduction in injury crashes (5). While several features of a turbo roundabout have been adopted in

few “turbo-like” roundabouts (e.g., Main Street in Mesa, Arizona; Utah Valley University, Orem, UT), there are

no standard/typical turbo roundabout installed yet in the U.S. (6).

While there are design standards/guidelines for turbo roundabouts in the context of transportation systems and

roadway users’ characteristics in several European countries, these standards cannot be readily transferable to the

U.S. The European design vehicle (e.g., tractor-trailer) is shorter than the U.S. standard tractor-trailer. Wider

circulating lanes or longer outer truck aprons are required to accommodate longer tractor-trailer(s) in the U.S. For

example, a wider opening width is required to accommodate the swept path of the U.S. tractor-trailer, according

to an analysis by Transoft Solution (6). Besides, driver behavior and familiarity towards roundabouts (in general)

and turbo roundabouts (in particular) are different (e.g., U.S. drivers are less familiar with roundabouts). The

Nevada DOT has been adopting roundabouts to improve safety and operations at intersections on their state

highways and is currently considering installing turbo roundabouts. Therefore, a detailed investigation using

microsimulation and driving simulator tools considering diverse roadway users (e.g., passenger cars, trucks,

pedestrians, bikes) and traffic volume composition (e.g., truck percentages and truck configurations) are critical

before any installation of turbo roundabouts in Nevada. An analysis of this kind (details presented in Research

Plan Section) will allow the development of design guidelines, installation criteria (e.g., warrants), and operational

recommendations that are specific to local (in this case, Nevada) roadway, traffic, and driver/user characteristics.

This project’s overall goal is to develop guidelines for the Nevada DOT on the installation and performance of

turbo roundabouts. As there are no known installations of turbo roundabout in the U.S., any kind of guidance that

can assist with decision making is not available for transportation engineers, professionals, and consultants.

Therefore, there is a need to synthesize and summarize current research, and more importantly, develop a

mechanism that guides practitioners on how to decide on the installation of a turbo roundabout, such as installation

criteria, design guidelines, safety and operational performance. To accomplish the project goal, the West Virginia

University (WVU) and Ohio University (OHIO) team aims to accomplish the following specific objectives:

[1] Conduct an extensive review and synthesis of current published research and pilot projects that compile the

design, installation, operation, maintenance, safety, and operational performance of turbo roundabouts;

[2] Conduct an extensive traffic microsimulation-based investigation that will provide insights on different design

factors in developing design guidelines, ensuring safety, and enabling effective operations and maintenance

of turbo roundabouts;

[3] Conduct a driving simulator-based investigation to understand navigability differences between traditional

and turbo roundabout designs and subsequently lead to identifying improvements or precautions (if any) that

would be needed in developing design guidelines and educational resources; and

[4] Develop a procedure (e.g., warrant analysis) and evaluation tool to assist transportation

engineers/professionals (Nevada specific) with further evaluation of turbo roundabout installation.

2. BACKGROUND SUMMARY

As intersection related traffic crashes represent approximately 50% of total traffic crashes (7), conversion of

traditional intersections (i.e., two- and all-way stop-controlled and signalized) to roundabouts has been a growing

practice in many countries around the world, including the U.S. The significant benefits of roundabouts include

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reducing crash frequency and severity, capacity improvement, and operational improvement. A study by the

Federal Highway Administration (FHWA) reported that a roundabout reduces intersection fatality by 90%, injury

by 76%, and crash frequency by 35% compared to a traditional intersection (8). The acceptance of roundabout

increases substantially after the installation as drivers become knowledgeable on navigating roundabouts (9).

According to Kittleson & Associates database, as of 2020, there are 4,963 single-lane and 1,826 multi-lane

roundabouts in the U.S. (10). However, multi-lane roundabouts have several operational challenges, such as

driver’s improper lane choice decisions due to driver confusion and traffic safety concerns due to traffic crashes

from weaving movements within roundabout (11). Emerging “turbo roundabout” can reduce several limitations

of multi-lane roundabouts. Turbo roundabout can effectively guide drivers within the roundabout by limiting

lane-changing and reducing associated lane-change related conflicts/crashes common in multi-lane roundabouts

(12). The turbo roundabout (illustrated in Figure A.1, Appendix A) was first designed and implemented in the

Netherlands (13). Turbo roundabout has the same general operating characteristics as modern roundabouts but

utilizes different geometrics and traffic control devices (12).

The key features of turbo roundabouts are explained and illustrated in Figure A.2 (Appendix A). Lane

separator/barrier between circular lanes in turbo roundabout keeps vehicles in the same lane, and prevents

weaving maneuvers. A study on seven intersections converted into turbo roundabouts in the Netherlands observed

an 82% reduction in the accident rate (13). Different turbo roundabouts can be identified based on the variable

number of lanes on the access and exit legs. A four-legged turbo roundabout may have five variations (a) basic,

(b) egg, (c) knee, (d) spiral, and (e) rotor. A description of each type of turbo roundabout can be found in the

extended literature review (Figure A.3, Appendix A).

User considerations in turbo roundabout design: Turbo roundabouts guide the motorists before entering the

intersection to choose the assigned lane for right-turn, through movement, left-turn, and U-turn by entry geometry,

enhanced delineation of lanes, and proper road marking and signage (12, 14). The navigation of pedestrians and

bicyclists through a turbo roundabout is like single-lane and multilane roundabouts. The guidelines for pedestrian

includes keeping sidewalks along the perimeter of the roundabout; crosswalks provided for pedestrian

convenience and safety; adding a splitter island sufficiently wide to accommodate pedestrian crossing that is also

accessible to pedestrians with disabilities as well as wide enough for comfortable queueing (12, 14, 15). The

decision of whether to add separated bicycle facilities at turbo roundabouts depends on factors such as bicycle

volume, the presence of existing bicycle facilities, traffic volume, the complexity of the roundabout, adjacent

infrastructure, land use, and right-of-way availability (12, 14). Motorcycle safety at roundabouts can be influenced

by raised lane dividers and curbing, surface friction, pavement markings, drainage, sight distance, radius, the

roadside environment, and surface conditions. Specific concerns for motorcyclists in turbo roundabouts are the

raised truck apron and lane divider. Sloped curbing with minimal vertical reveal can be provided for a safer

environment for motorcycles than vertical or rolled curbing. Additional signage alerting motorcyclists to these

elements of turbo roundabouts can also be provided (14).

As vehicles aren’t allowed to change lanes within a turbo roundabout, it is critical to provide sufficient space for

large trucks to complete the movements/turning. In European design guidelines for turbo roundabouts, the

dimension of the design vehicle is considered so that design vehicles do not track into adjacent lanes (16).

However, trucks are larger in the U.S. compared to Europe. When a raised lane divider option is used, a traversable

and demarcating feature can be provided at the origin of the raised divider to ease the entrance of larger vehicles

(12). A central truck apron can be provided in turbo roundabouts to help larger vehicles to navigate the

intersection. Aprons can also be provided on the turbo roundabout's perimeter to provide more turning space for

large trucks (12). Accommodation of different user groups (i.e., motorists, pedestrians, bicyclists, motorcyclists,

and freight/large vehicles) at turbo roundabouts can be found in the extended literature review (Appendix A).

Location considerations: Site characteristics that can influence the feasibility of a turbo roundabout include right-

of-way limitations, intersection skewness, winter maintenance needs, and downstream bottlenecks. Turbo

roundabouts may be considered at an intersection where traffic demand indicates the need for a multilane

roundabout (12).

Design considerations: The geometric design of a turbo roundabout depends on the desired capacity and the

desired characteristics of a design vehicle’s horizontal swept path. The projected demand and the approach

roadway cross-sections determine the number of lanes/lane arrangement, which dictate the type of turbo

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roundabout to be built. After selecting the type, a horizontal swept path analysis of the design vehicle is done to

choose lane width and other lane width-related considerations (e.g., right-of-way, considerations for all vehicle

types and users) (12). Current guidelines in terms of horizontal design components of turbo roundabout (i.e.,

Turbo Block, Lane and Roadway Width, Central Island, Lane Divider, Approach Geometry) are discussed in the

extended literature review (Appendix A).

Adequate stopping and decision sight distance should be provided for all users at all approaches of a turbo

roundabout. NCHRP Report 672 provides guidelines for evaluating sight distance and visibility at roundabouts

(14). Signage and pavement markings on the approaches, especially for lane selection, are critical for motorists

to identify and select their desired lane before entering the turbo roundabout. Lane control signage can be

supplemented using pavement marking arrows (12). Supplemental delineation can be achieved using reflectors

or light-emitting diodes (LEDs) to illuminate the edges of the apron and lane dividers (12, 17). Consideration of

pedestrian, bicycle, vertical alignment, lighting, landscaping, and other design aspects are presented in the

extended literature review (Appendix A).

Safety performance of turbo roundabout: As turbo roundabouts are still an emerging concept, international safety

studies based on an analysis of crash data are limited and not yet available based on any U.S. installation. In the

Netherlands, seven intersections were converted to a turbo roundabout and reported an 82% percent reduction in

the number of injury crashes (4). A study in Poland found that turbo roundabouts with a raised lane divider

experience a lower crash frequency than those with paint stripes only, and the researchers observed lower severity

crash outcomes in both cases (18). Surrogate safety measures based on microscopic traffic simulations have also

indicated that turbo roundabouts are likely to experience less frequent and less severe crashes than multilane

roundabouts (19, 20, 21, 22, 23).

Operational performance of turbo roundabout: Another advantage of the turbo roundabout is that the traffic flow

on lanes can be much more balanced (13). Similar to traditional roundabouts, the capacity of turbo roundabout is

measured at the approach level. International studies suggest that basic turbo roundabouts have a similar capacity

as multilane roundabouts with two entry and two circulating lanes. One study in the Netherlands estimated a

capacity for a basic turbo roundabout design of approximately 3,500 pc/h for all entries combined, assuming

conflicting traffic volumes between 1,900 and 2,100 pc/h (24). For estimating turbo roundabout capacity, gap-

acceptance models that consider critical headway, critical follow-up time, and conflicting traffic appear to be

adequate. A study in Poland found that the Highway Capacity Manual (HCM) capacity models for roundabouts

estimated the capacity of Polish turbo roundabouts with reasonable accuracy (25).

Costs: As turbo roundabouts are similar to multilane roundabouts, they are expected to have similar costs as multi-

lane roundabouts. Turbo roundabouts may vary slightly from multilane roundabouts in terms of right-of-way

requirements. A radial entry with no flare and smaller entrance radius requires a larger swept path for large

vehicles, which will lead to a wider circular roadway than for a comparable multilane roundabout. However, there

may not be significant changes to the alignment of the approach roadway given the entry geometry of the turbo

roundabout (12).

As there are no turbo roundabout design guidelines in the U.S. considering operational and safety performance of

different design features, a detailed investigation using microsimulation and driving simulator tools considering

diverse roadway users and traffic composition is timely to promote turbo roundabout in Nevada. The following

section summarized the research plan to be applied to facilitate the development of design guidelines and

installation criteria (e.g., warrants) specific to local (in this case, Nevada) roadway, traffic, and driver

characteristics.

3. PROPOSED RESEARCH

The work plan that has been developed is based on the scope of work defined within the RFP solicitation. The

WVU and OHIO research team has planned nine tasks to be completed in an orderly and timely manner to

accomplish the research objectives. These specific tasks include Task 1. Hold project start-up meeting; Task 2.

Review pertinent existing literature and best practices; Task 3. Perform microsimulation-based assessment; Task

4. Perform human factors (or driver experience) assessment; Task 5. Develop a selection procedure for turbo

roundabouts as intersection control option; Task 6: Develop educational materials and conduct effectiveness

analysis; Task 7: Develop implementation plan; Task 8. Develop recommendations and final project report; and

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Task 9. Conduct project management tasks. The proposed research is expected to be completed in 24 months.

The project schedule section shows a detailed tentative timeline needed to complete tasks 1 to 8. This timeline

includes 23 months to complete project Tasks 1-8 and compile a draft report, and one month for review and

publication of the final project report. Details regarding each task and subtasks are presented below.

Task 1. Hold project start-up meeting

In the first month of the project contract award, the WVU and OHIO research team will schedule a virtual meeting

(e.g., ZOOM platform) with Nevada DOT’s project technical panel assigned to this project to present, discuss,

and finalize the following: detailed work plans, the scope of work, research methodology and tasks, project

duration/timeline, and deliverables.

Task 2. Review pertinent existing literature and best practices

For this task, extensive literature searches will be conducted through web-based queries as well as queries through

specific agency search engines (such as the Transportation Research International Database, NCHRP Projects,

Google Scholar, ScienceDirect, JSTOR, BIOSYS, and ResearchGate). Overall, and to the best knowledge of the

authors, there have been no adoptions/pilot projects of turbo roundabouts in the U.S. Though, there has been some

traction at FHWA, various state agencies, and consultant level to discuss possible implementation of this

alternative roundabout design. As turbo roundabouts have been adopted in Europe in the last few decades, this

literature search intends to summarize the design standards and safety and mobility benefits experiences. A library

search through the West Virginia University, OHIO Link, and OHIO library systems will be undertaken.

All available documentation (e.g., papers, synthesis reports, brochures) will be critically reviewed and targeted at

providing comprehensive and detailed insights on turbo roundabouts, including (but not limited to) the following:

[1] What design criterion (e.g., radii, entry point features, markings, signage) are standard, and adopted by

European countries for turbo roundabouts? This may entail direct communication with responsible parties in

European countries. [2] What considerations need to be made in terms of placement? That is, what

traffic/truck/pedestrian/bike volumes, roadway elements, environmental, safety, locale requirements need to be

evaluated to maximize benefit? [3] What are the operational, safety, and environmental improvements attained

from turbo roundabouts? [4] Any intersection performance advantages (e.g., capacity) of adopting turbo

roundabouts? [5] Any specific guidance – “best” practices, maintenance procedures, right-of-way requirements

in the use of turbo roundabouts?

Additionally, via email correspondence and/or phone interviews, the research team will reach out to the authors

of research articles related to turbo roundabouts. This personal communication will allow the research team to

get additional insights beyond that detailed in any existing literature. A comprehensive state-of-the-art literature

review will be prepared to contain the summaries and critiques from different perspectives, including; geometric

design, construction and maintenance, operations, safety, and driver experience. A report will be prepared as

the deliverable of this task and will be submitted to Nevada DOT. Appendix A summarizes an extended

literature review.

Task 3. Perform micro-simulation assessment

The research team adopts a micro-simulation approach to investigate the safety, and operational impacts of

different turbo roundabout design features considering diverse roadway users (e.g., passenger vehicle, truck,

pedestrian, bicyclist) in the U.S. Micro-simulation models “mimic closely the stochastic and dynamic nature of

both the vehicle-to-vehicle and vehicle-to-traffic interactions that occur within the transportation system” (26).

Additionally, variations in traffic volumes and their compositions (e.g., truck percentage and design vehicle

size/dimensions) will be incorporated to investigate the suitability of intersection traffic volume and composition

in determining the design features of a turbo roundabout. Operational measures such as delay, capacity, and LOS

will be reported to determine appropriate roundabout features. It is anticipated that findings of this task will (i)

provide insight into selecting relevant design features and dimensions for specific locations and traffic conditions,

and (ii) guide decisions regarding the installation of turbo roundabout. Simulation models developed using

VISSIM provide simulated vehicle tracking data (trajectories) that will be analyzed using the Surrogate Safety

Assessment Model (SSAM) developed by the FHWA (27) to perform conflict analysis to estimate safety

performance. The integration of microsimulation and surrogate safety performance measures allows for the

assessment of safety and operational benefits.

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The WVU/OHIO research team will use a combination of micro-simulation tools, VISSIM, SAAM, and

specialized roundabout design and analysis tool (e.g., TORUS) in accomplishing this research task. It should be

noted that SIDRA is a popularly tool for roundabout analysis. However, at present, the functionality offered by

SIDRA does not allow analysis involving turbo roundabouts (Personal communication, December 2020).

Task 3.1: Site selection

In this subtask, the research team will work with Nevada DOT to identify several intersections that are likely to

be considered candidates for future turbo roundabout installation. Based on a prior discussion between the

research team and the project champion and co-champion, several two-lane roundabouts in Washoe County and

Southern Nevada might become the first few locations to be considered for conversion to turbo roundabout. The

research team plan to consult with the Nevada DOT project technical panel to determine few potential

intersections for detailed data collection (e.g., traffic/pedestrian/bike data, right-of-way, operational data) be used

in the development of a calibrated model of existing conditions.

Task 3.2: Data collection at selected sites

Traffic (e.g., vehicular count and classification, pedestrian and bike volume) and geometric feature data (e.g.,

number of lanes, lane width, grade) will be collected at selected intersection locations. Traffic flow, turning

movement counts, speed, and directional distribution data for each approach will be collected, including available

right-of-way measurements to investigate the availability of right-of-way for modifications needed in turbo

roundabout. A typical weekday peak morning and evening peak hours traffic volume data will be collected for

the simulation scenario development purpose. The research team will work with the local transportation officials

for this data collection.

Task 3.3: Development of the calibrated models

VISSIM models will be developed and calibrated to replicate the selected intersections. The objective of

calibration is to create a simulation model that represent field conditions with reasonable accuracy. The calibration

process can be done by comparing simulation model outputs with field measurements (e.g., average speed, queue

length, travel time, delay).

Task 3.4: Simulation scenario development

Scenarios for microsimulation of turbo roundabout will be developed mainly based on turbo roundabout

geometric features (e.g., turbo block, radius, lane width, central island, lane divider, approach geometry),

passenger vehicle/truck/pedestrian/bike volume, design vehicles, directional splits. Turbo roundabouts usually

have diameters (D) in the range of 131 to 164 feet (28). A basic turbo roundabout with four legs and two lanes in

each approach will be considered for simulation. Inner circular roadway and outer circular roadway widths and

other design parameters will be varied in the development of simulation scenarios (2). Heavy vehicles percent

might have a significant effect on operational performance in a turbo roundabout, as heavy vehicles require more

space for safe turning and movement while entering and navigating through the roundabout. In this research,

TORUS, a turbo roundabout design software, will be used to determine the key geometric features (e.g., circular

lane width, minimum radius for each design vehicle, swept path) of a turbo roundabout. We plan to consider

multiple design vehicles and will be finalized by seeking feedback from the Nevada DOT project technical panel.

In addition, heavy vehicle percent will be varied, and different directional splits (e.g., 60-20-20 right turning-

through-left turning movements) will be considered. We will work with the Nevada DOT project technical panel

in finalizing the simulation scenarios.

Task 3.5: Simulation and estimation of performance measures

Various operational performance measures (e.g., average control delay, average geometric delay, effective

intersection capacity, queue length, average travel speed) data will be collected as output using the VISSIM

simulation platform. These data will be analyzed for evaluation of the operational performance of each scenario

compared to base condition (e.g., two-lane roundabout, all-way/two-way stop-controlled). Vehicle trajectory file,

which includes vehicle speed, acceleration, location, will be generated in VISSIM for each scenario to conduct

safety assessment by estimating conflicts. For safety analysis, SSAM software developed by FHWA will be used

to estimate the total number of conflicts, including conflict types and locations. This safety analysis will be used

to determine which design alternatives of turbo roundabout will be the safest. A report will be prepared as the

deliverable of this task and will be submitted to Nevada DOT. Both PIs in this proposal have been doing a

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similar type of microsimulation-based study to assist transportation engineers in Ohio with developing guidelines

for designing mini-roundabouts using SIDRA, VISSIM, and SSAM.

Task 4. Perform human factors (or driver experience) assessment

From a design perspective, turbo roundabout offers promising means to reduce intersection crashes. However,

from a human factors’ perspective, what is the best design alternative considering the complex driving behavior

(that differs within any driver population based on factors such as age, gender, and years of driving experience,

among others) were often overlooked, which limits the achieved benefits and effectiveness of safety

improvements.

Specific to roundabout designs, one of the factors that negatively affect the adoption of roundabouts is public

attitudes (29). McKnight et al. hypothesized that confusion in navigating a roundabout would depend on the

amount of knowledge of the driver (30). Drivers who oppose roundabouts and those who are not confident in

navigating the intersection were also found to have less knowledge of proper navigation. Fear of roundabouts has

been found in different studies and thought to be a product of driver confusion, vulnerability, and lack of

navigational understanding (31, 32). Therefore, in developing design guidelines for any roadway facility and/or

element – in this case, turbo-roundabouts – it is important to incorporate the drivers’ experience, especially that

any advantages (or disadvantages) attributed to the facility depend upon drivers understanding and behavior. In

transportation engineering, driving simulators (i.e., human-in-the-loop simulations) have been used to study

different roadway geometric designs and their alternatives, study signal controls, study signs and pavement

markings, collision studies, distracted driving, or only for visualization and training purposes (34, 35, 36, 37, 39,

40, 41). OHIO’s driving simulator (Figure 1) has been used for numerous driver behavior research projects. The

simulator can produce realistic driving environments with specifically designed scenarios and can measure a

subject’s speed, acceleration, deceleration, lane position, reaction time, and other performance metrics. In

addition, to understand responses to various driver workloads, driver physiological data (e.g., heart rate, heart rate

variability, EEG, and ECG) are also collected using non-invasive monitoring devices.

Figure 1: Ohio’s driving simulator

This task will aim to explicitly investigate the experience(s) of the driver with respect to navigating a turbo-

roundabout. The goal is to gain insight – from a human factors’ perspective – into any differences that may exist

between driver performances with the navigation of turbo versus two-lane and/or single-lane roundabout designs.

It is anticipated that the performance will be measured in terms of gap acceptance, approach versus circulating

speed, and lane selection to identify the reason(s) for driver confusion during roundabout navigation. Detailed

below are sub-tasks that will be adopted to complete this driving simulator-based human factors assessment task.

Task 4.1. Submission of Institutional Review Board (IRB) approval

The research team is committed to full compliance with all applicable laws and regulations governing human

subjects research. Therefore, before starting the experiments, the research team will submit all necessary

documentation to the Ohio University IRB for review and approval.

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Task 4.2. Develop simulator scenarios

Given that turbo roundabouts are not a typical intersection control type, specific simulation tiles will need to be

created. Once created, these turbo roundabout tiles will be incorporated into simulation scenarios (i.e., a realistic

network consisting of a road network with different roadway elements). The driving scenarios will be designed

in a manner such that drivers would be exposed to various roundabout designs (e.g., turbo, single and multi-lane)

and to signalized and stop-controlled intersections. The scenarios will include day versus night driving and driving

under different weather conditions. A driving scenario of approximately 15-20 miles consists of turbo/single- and

multi-lane, signalized, and the stop-controlled intersection will be used in this research.

Task 4.3. Participant recruitment

Participants (i.e., volunteer drivers) from different age groups will be recruited and asked to drive through the

simulated scenarios. Each participant will be recruited following the approved IRB protocol and on a purely

voluntary basis and will not receive any compensation. An effort will be made to recruit participants that would

be representative of the existing Nevada driver population-based upon gender and age distributions. It is

anticipated that age groupings will be established based on previous studies (42, 43, 44, 45). An overall

recruitment goal range of 32 to 54 drivers will be set to conduct statistical analyses with a sufficient sample size.

Task 4.4. Run test and experiment drives

A participant will arrive at the Safety and Human Factors Laboratory, will be informed of the consent policy

(including privacy requirements and potential risks associated), and drive the developed simulation scenarios.

Researchers will record the driving behavior and performance to quantify driving experiences in navigating a

turbo roundabout. A pre-and post-driving questionnaire will be administered before and after he/she is exposed

to the driving simulator scenarios. The objective is to gain a broader understanding of driver’s

reactions/challenges to turbo roundabouts and the degree to which factors such as age, gender, driving frequency

impact the responses.

Task 4.5. Statistical analysis and reporting – Data obtained from the simulator experiments will be analyzed by

employing various statistical techniques depending upon the type of data to be analyzed and the desired outcomes

of the analysis. Findings from the data analysis will be documented as a deliverable to Nevada DOT. A report

will be prepared as the deliverable of this task and will be submitted to Nevada DOT.

Task 5. Develop a selection procedure for turbo roundabouts as an intersection control option

Based on the findings from Tasks 2, 3, and 4, it is anticipated that this task will establish criteria (i.e., warrants)

and evaluation toll that should assist transportation professionals with the evaluation of turbo roundabout

installation. Note, while these criteria will be specific to local (Nevada) conditions, they will address a variety of

intersection conditions such as vehicular volume, turning movements, pedestrian and bike volume, design vehicle,

the potential safety and operational benefits over the existing condition. A Turbo Roundabout Evaluation (TRE)

tool will be developed to conduct the warrant analysis and performance comparison of an existing intersection in

terms of converting to a turbo roundabout. A report and TRE tool will be prepared as the deliverable of this

task and will be submitted to Nevada DOT.

Task 6. Develop educational resources and conduct effectiveness analysis

Educational materials (e.g., short reports, recorded presentation, flyers) in terms of design and operational aspects

of turbo roundabout based on the research findings will be developed to assist transportation engineers, planners,

and consultants in Nevada. We will work with the Nevada DOT project technical panel to identify a number of

transportation engineers, planners, and consultants to review the educational materials and gather their feedback.

The educational materials will be revised based on their feedback for broader dissemination. To minimize public

resistance to new forms of intersection controls (e.g., mini roundabout, turbo roundabout), transportation agencies

conduct public outreach activities before installing new solutions. Generally, a multi-prong approach to reach out

a maximum number of citizens is recommended as there are differences in how people receive news (e.g., radio,

tv, print media). In this project, we will focus on developing flyers that could be used by Nevada DMV to

distribute to registered drivers in Nevada. An upgraded version of the flyer will be developed for potential

inclusion in Nevada Motorist’s handbook. Several agencies have developed videos available via YouTube.

Nevada DOT could promote and distribute these readily available videos to all relevant public and private

agencies and encourage them to be included in the driver training programs. We will identify such resources and

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shared them with Nevada DOT. Additional strategies such as engaging locals in the design process, advertisement

in the local newspaper, public engagement events, setting up walkable mock turbo roundabout will also be

explored, and recommendations will be developed for Nevada DOT and local transportation agencies on public

outreach best practices. Products developed in this task will be submitted to Nevada DOT as deliverables.

Task 7. Develop an implementation plan

This project aims to investigate the potential of implementing turbo roundabouts in Nevada. As such, the final

deliverables will be from Tasks 5 and 6 – selection procedure for turbo roundabouts and TRE tool and educational

resources, respectively. In this task, the research team will develop an implementation plan that will allow the

Nevada DOT to adopt and use the developed design guidelines for considering turbo roundabouts. The research

team will work with the technical panel, project champions, and other Nevada DOT personnel to formulate and

develop an implementation plan. Additional explanations of the implementation plan are discussed in the

“Implementation Plan” section. A report will be submitted to Nevada DOT as a deliverable.

Task 8. Develop recommendations and final project report

In this task, the WVU/OHIO research team will prepare a draft interim report documenting all the activities,

analyses, findings, and results. Additionally, a fact sheet summarizing the work performed, key findings, and

conclusions will also be prepared. All documents will be presented in a format required (and acceptable) to

Nevada DOT procedures. The research team will submit electronic copies of the draft interim report and all other

supporting documents no later than one month prior to the project completion date. Based on the comments

received from the Nevada DOT project technical panel, the research team will revise the draft interim report and

supporting documents. WVU will then submit electronic copies of the approved interim report and all

supporting documents by the project completion date.

Task 9. Conduct project management tasks

The project management task will encompass activities associated with the reporting requirements and meetings

related to the project. During the 24-month timeframe for this project, eight quarterly progress reports will be

developed by the research team and submitted to Nevada DOT detailing the progress of the research study. A

virtual project start-up meeting will be scheduled during the first month of the project. Additionally, the research

team will provide additional status updates to the technical panel as needed.

4. URGENCY AND ANTICIPATED BENEFITS

Urgency: Due to the significant safety benefits, more than 370 intersections in the Netherlands have been

converted to turbo roundabout. Adopting turbo roundabout has great potential to reduce intersection related

crashes in Nevada and contribute to the “ZERO FATALITIES” target. As there are no design guidelines for the

installation of turbo roundabouts in the U.S., and Nevada DOT has been promoting different forms of roundabouts

to improve traffic safety, this research project can accelerate the adoption of turbo roundabout and could save

lives by assisting traffic engineers, planners, and consultant with turbo roundabout design guidelines based on

safety and operational performance of design alternatives. This project will accelerate the deployment of turbo

roundabouts in Nevada.

Anticipated benefits: According to the “Nevada Strategic Highway Safety Plan (SHSP),” 286 people died, and

2,070 people sustained serious injury from intersection related traffic crashes between 2013-2017 which had

substantial economic/societal cost. Geometric improvement of intersection based on engineering analysis has

been considered as one of the three action steps in reducing intersection related fatalities and serious injuries in

Nevada. Turbo roundabout has been implemented in many European countries and has demonstrated a significant

reduction in traffic crashes. Assuming similar benefits (i.e., 82% reduction in intersection injury crashes in the

Netherlands), installation of turbo roundabouts could reduce intersection related crashes substantially and help

Nevada DOT make significant progress toward the “ZERO FATALITIES” target. However, it is important to

conduct studies to adopt turbo roundabout considering unique transportation system characteristics (e.g., large

trucks in the U.S., pedestrian/bike) which are different from Europe. This project will develop turbo roundabout

design and installation guidelines for Nevada DOT considering the traffic, design vehicle, and user characteristics.

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5. IMPLEMENTATION PLAN

Considering the project's scope, the research team identify this project as “Laboratory Prototype Stage.” The

research team plan to conduct microsimulation and driving simulator-based experiments to develop guidelines on

the implementation of turbo roundabout considering various design aspects and user experiences. The primary

target audience for this research results is the Nevada DOT intersection improvement planning personnel and

consultants. Impediments to the successful adoption of research products may occur due to the unavailability of

resources to adopt turbo roundabout, which is expected to be resolved in this project by developing installation

guidelines. We will work closely with the project technical panel to identify any additional research needs that

could be easily be explored in this project. We strive to produce research findings, reports, educational materials,

and the TRE tool suitable for smooth and immediate (or near-term) implementation. Additional future activities

may be necessary for successful implementation, such as preparing well-designed training sessions for

practitioners and field evaluation of pilot turbo roundabout. Special attention will be to identify implementation

costs to facilitate the adoption of research products. Practitioners can readily adopt all research products of this

project. We expect that Nevada DOT will do a pilot deployment of turbo roundabout, which will cost

substantially. We also recommend conducting a before and after study at pilot turbo roundabout installations. The

research team will maintain continuous communication with Nevada DOT to provide all necessary assistance in

planning and conducting implementation-related activities.

6. PROJECT SCHEDULE

The experienced research team comprises researchers from WVU and OHIO, who will work collaboratively to

complete the tasks outlined within the proposed research. The following table shows the project schedule by tasks

with a start date of May 1, 2021.

7. FACILITIES AND EXPERTISE

Facilities: The completion of this research project will rely on technical resources available at WVU and OHIO.

Both institutions maintain the organizational capacity and available resources required to complete the proposed

research tasks. In general, the facilities within the departments of Civil Engineering (at WVU+ OHIO) include

graduate student offices for research equipped with state‐of‐the‐art computers having all necessary software

packages for this project including; VISSIM, TORUS, Microsoft Office software suite; and Statistical and

Econometric modeling software (LIMDEP, NLOGIT, JMP, SPSS, and R); and programming software (Python,

JavaScript). At WVU, Dr. Dey has access to VISSIM and SSAM to be used in this project. In addition, WVU

will purchase specialized software TORUS. At OHIO, the Safety and Human Factors Facility is home to a Drive

Safety Research Simulator – a high-fidelity driving simulator that is fully integrated with a full-width Ford Focus

automobile driver and passenger compartment. The simulator includes a Q-Motion platform that provides inertial

cues representing acceleration and deceleration with longitudinal travel up to five inches and a pitch range of 2.5

1 2 3 4 5 6 7 8 9 10

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12

13

14

15

16

17

18

19

20

21

22

23

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1 Hold project start-up meeting

2 Review pertinent existing literature and best practices

3 Perform microsimulation assessment

4 Perform human factors (or driver experience) assessment

5Develop a selection procedure for turbo roundabouts as

intersection control option

6Develop educational resources and conduct effectiveness

analysis  

7 Develop implementation plan

8 Develop recommendations and final project report

9 Conduct project management tasks

Quarterly Reports

Deliverables

Year 1 Year 2

Ta

sk#

Task Title Months

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degrees. The simulator includes several standard data collection measurements and allows for up to 25 additional

user-defined measurements. In addition, an eye-tracking system is available, which monitors gaze direction, eye

closure, facial gestures, and head position. The eye tracker automatically correlates eye fixation data from the eye

and face to the dynamic simulator data. Other Standard office and communication equipment available in the

main offices of WVU and OHIO include color and black/white high-speed copiers, photocopiers, scanners, video

conference systems, and fax machines that will be used during the execution of this project.

Expertise: Drs Kakan Dey (WVU) and Dr. Bhaven Naik (OHIO) are the PIs of a research project on the

development of design guidelines for mini roundabout funded by Ohio Department of Transportation.

Dr. Kakan Dey, PE is an Assistant Professor in the Department of Civil and Environmental Engineering at West

Virginia University. Dr. Dey conducted several projects on traffic-micro-simulation for Ohio DOT, South

Carolina DOT, and Morgantown Monongalia MPO. He is the Co-PI in an on-going Ohio DOT funded project

on mini roundabout design guideline development. He published three peer-reviewed journal and conference

articles using VISSIM and SSAM. He received his Ph.D. in Civil Engineering with Transportation Systems in

2014 from Clemson University in South Carolina. He was the recipient of the Clemson University 2016

Distinguished Postdoc Award. Dr. Dey’s primary research interests include Traffic Operations, Traffic Safety,

Intelligent Transportation Systems (ITS), Connected and Autonomous Vehicle Technology, Data Analytics, and

Artificial Intelligence Applications. He published more than 40 peer-reviewed research papers on different

transportation engineering topics. Dr. Dey is a Standing Committee Member of the Transportation Research

Board (TRB) the TRB Artificial Intelligence and Advanced Computing Applications (ABJ70), and Truck Size

and Weight Committee (AT055). He is also a member of the ASCE Freight and Logistics Committee.

AASHTO’s Research Advisory Committee recognized two of Dr. Dey’s research projects as “High Value

Research Project” in 2014 and 2012 (Listed in the CV, Appendix B).

Dr. Bhaven Naik, PE, PTOE is an Associate Professor with Ohio University’s Dept. of Civil Engineering since

August 2014. Prior to his current appointment, he worked with the Mid-America Transportation Center and the

Nebraska Transportation Center at the University of Nebraska. Over the last 18 years, Dr. Naik has been involved

in high impact transportation research projects in the areas of highway safety & human factors, microsimulation

modeling, geometric design, traffic operations & signal timing optimization, ITS, and CV/AV technologies. Dr.

Naik also has expertise in statistical methods and has been involved with projects requiring rigorous statistical

analysis. Specific to this project, Dr. Naik has experience with providing technical guidance to state agencies and

graduate student research thesis’ and dissertations related to work involving roundabouts, HRGCs, geometric

design elements, etc. Of particular interest is his current research with Ohio DOT entitled “Intersection

Modifications using Mini-/Modular-Roundabout Methods” and the 2016 master’s thesis work for Erica Toussant

entitled “Analyzing the Impacts of Driver Familiarity/Unfamiliarity at Roundabouts.”. His dedication to research

is demonstrated by peer-reviewed publications he has authored/co-authored, such as “Safety Effect of Dilemma-

Zone Protection Using Actuated Advance Warning Systems,” “Safety Effectiveness of Offsetting Opposing Left

Turn Lanes.” Dr. Naik has been effective in communicating of research procedures, results and applications to

State DOTs, the Transportation Research Board, and the general public. Dr. Naik’s past relevant projects and

experience are listed in the CV (Appendix B).

8. PROJECT CHAMPION, COORDINATION, AND INVOLVEMENT (OTHER DIVISIONS)

Both PIs (Drs. Dey and Naik) had a conference call using the ZOOM platform with the Champion and Co-

champion to understand the RFP background. In addition to their expectations of this project, we learned that

there are few two-lane roundabout sites in Washoe county and Southern Nevada which are most likely to be

considered for installing turbo roundabout. We envision to conduct all research activities considering these

potential sites as base conditions. The assistance required by the WVU/OHIO research team from Nevada DOT

during this project will be as follows: (i) Assist with scheduling project meetings and attending project meetings;

(ii) Assist research team with technical direction, clarifications, comments, and information as necessary; (iii)

Assist with identification of potential locations for turbo roundabout implementation, traffic data for these

potential locations, and contact information for local engineers; and (iv) Review and provide comments on the

deliverables, the draft final report, and draft executive summary.

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9. BUDGET

Total Budget- West Virginia University

12

Subcontract budget- Ohio University

13

10. APPENDIX A: EXTENDED LITERATURE REVIEW

As intersection related traffic crashes represent approximately 50% of total traffic crashes, geometric

modifications to existing intersections are explored over the years by traffic engineers and researchers.

Conversion of traditional intersections (i.e., two- and all-way stop control and signalized) to roundabouts has been

a growing practice in many countries around the world, including the U.S. – largely due to the benefits in terms

of reduction in crash frequency and severity, and capacity and operational improvement. A study by the Federal

Highway Administration (FHWA) reported that a roundabout reduces intersection fatality by 90%, injury by 76%,

and crash frequency by 35% in comparison to a traditional intersection (8). While most people are opposed to

roundabouts before implementation, the acceptance increases substantially after installation over time as drivers

become knowledgeable on navigating roundabouts (9). The use of roundabouts is a proven safety strategy for

improving intersection safety by eliminating or altering conflict types, reducing crash severity, and causing

drivers to reduce speeds as they proceed into and through intersections (14). Converting a traditional at-grade

signalized intersection to a modern roundabout is expected to reduce the number of injury crashes by 78 percent,

and converting a traditional two-way stop control intersection to a modern roundabout is expected to reduce the

number of injury crashes by 82 percent (46). According to Kittleson & Associates database, as of 2020, there are

4,963 (71%) single-lane and 1,826 (26%) multi-lane roundabouts in the US (10). Though the number of multi-

lane roundabouts in the US is currently less than half of single-lane roundabouts, multi-lane roundabouts have a

huge potential for the future due to high traffic flow capacity. The FHWA Roundabout Guide (NCHRP 672) has

estimated that a multi-lane roundabout can operate up to 45,000 entering vehicles per day (14), and reduces

congestion and delay (11). However, multi-lane roundabouts have several operational challenges: driver

perceptions about the roundabout, proper lane choice decisions due to driver confusion, striping and signing

issues, bicycle and pedestrian concerns, and ADA (Americans with Disabilities Act) compliance, and traffic

safety due to frequency of traffic crashes (11). In a multi-lane roundabout, drivers are often confused about lane

choice to correctly navigate the roundabout, which leads to two major crash types associated with yielding to the

traffic within the roundabout, and changing lanes within the multi-lane (i.e., making a right turn from the left lane

or making a left turn or U-turn from the right lane) (11).

The emerging turbo roundabouts concept has the potential to reduce the limitations of multi-lane roundabouts.

Turbo roundabout can effectively guide driver behavior within roundabout by limiting lane-changing and

reducing associated lane-change related conflicts, which are common in multi-lane roundabouts (2). Turbo

roundabout was first designed and implemented in the Netherlands in the 1990s (4). Figure A.1 shows a turbo

roundabout from Delft, Netherland (47). It has the same general operating characteristics as modern roundabouts

but utilizes different geometrics and applications of traffic control devices (2). This literature review describes

the characteristics of turbo roundabouts, highlights the design and traffic control features, operational capabilities,

and potential safety benefits of these roundabout alternatives.

Figure A.1: A turbo roundabout in Delft, Netherland (image from Google Maps) (47)

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Turbo Roundabout Characteristics

Turbo roundabouts possess distinct characteristics compared to modern multi-lane roundabouts. According to

Fortuijn (the inventor of turbo roundabout), the key features of turbo roundabouts are explained and illustrated in

Figure A.2 (13):

Figure A.2: Turbo roundabout key features based on Fortuijn, 2009 (2)

Different Types of Turbo Roundabout

Different types of turbo roundabout can be identified based on a variable number of lanes on the access and exit

legs. A four-legged turbo roundabout may have five variations (illustrated in Figure A.3)- (a) basic, (b) egg, (c)

knee, (d) spiral, and (e) rotor. “Egg” turbo roundabout is similar to “basic” turbo roundabout, except the minor

approaches consist of only one lane. An inside lane is only added on one approach in a “knee” turbo roundabout.

“Spiral” turbo roundabout has three circulatory lanes with inside lane only added on two approaches. Two

approaches consist of three lanes, and two approaches consist of two lanes in a “spiral” turbo roundabout. “Rotor”

type also has three circulatory lanes with an inside lane added on each approach. All approaches consist of three

lanes for “spiral” turbo roundabout (2).

(a) (b)

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(c) (d)

(e)

Figure A.3: Different types of turbo roundabouts with capacity (2)

Advantages of Turbo Roundabout

The main advantage of turbo roundabouts is safety improvement due to a decrease in conflict points in turbo

roundabouts compared to traditional roundabouts. Figure A.4 illustrates conflict points for two-lane traditional

roundabout and turbo roundabout. Lane barrier between circular lanes in turbo roundabout keeps vehicles in the

same lane (to be selected by drivers before entering the roundabout). It prevents weaving maneuvers (lane-

changing within turbo roundabout) causes sideswipe collisions in a traditional roundabout. A study on 7

intersections (including intersections with yield control, intersections with traffic lights, and an old-style rotary)

that were converted into turbo roundabouts in the period 2000–2002 in the Netherlands observed an 82%

reduction in the accident rate (4). Another advantage of the turbo roundabout is that the traffic flow on lanes can

be much more balanced within the turbo roundabout (4).

(a) (b)

Figure A.4: Conflict points for a two-lane modern roundabout and a turbo roundabout (2)

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User Considerations in Turbo Roundabout Design

The accommodation of different user groups (i.e., motorists, pedestrians, bicyclists, motorcyclists, and

freight/large vehicles) at turbo roundabouts are discussed in this section.

Motorists

Turbo roundabouts guide the motorists in advance before entering the intersection to choose the assigned lane for

a right turn, through movement, left turn, and U-turn by entry geometry, enhanced delineation of lanes, and proper

road marking and signage. Drivers are required to identify acceptable gaps in no more than two conflicting lanes

at the entrance to a turbo roundabout. A roundabout directional arrow sign is placed directly in the drivers’ field

of view, which directs drivers to enter the circulatory roadway in the appropriate direction (2). These signs

increase the conspicuity of the central island and communicate to drivers about the need to slow down to go

through the roundabout (4). The Roundabouts Informational Guide (NCHRP 672) also recommends using

landscaping to increase central island conspicuity (14). One difference between modern roundabouts and turbo

roundabouts is that vehicles can make U-turn from all approaches in a modern roundabout, but not in a turbo

roundabout. The approaches and lanes from which vehicles can or cannot perform U-turns vary based on the turbo

roundabout types. In Figure 3a, vehicles entering from the inside lane of the east and west approaches (i.e., major

road approaches) can complete a U-turn, while vehicles approaching from the north and south approaches (i.e.,

minor road approaches) cannot complete a U-turn. Thus, it is important to consider the frequency of U-turn

maneuvers at an intersection when evaluating turbo roundabouts as a potential alternative (2).

Pedestrians

The navigation of pedestrians through a turbo roundabout is similar to single-lane and multilane roundabouts.

The guidelines from NCHRP Report 834 can be followed in this regard, which are summarized below (2, 14, 15):

1. Keep sidewalks along the perimeter of the roundabout, separated from the edge of the circulatory roadway

with a landscaped strip or buffer.

2. Where crosswalks are provided, locate them for pedestrian convenience and safety, where drivers can be

expected to yield the right-of-way, and where the crossing will be less likely to be blocked by queued

vehicles.

3. Provide a splitter island sufficiently wide to accommodate a pedestrian crossing that is accessible to

pedestrians with disabilities as well as wide enough for comfortable queueing.

Bicyclists

Bicycle features at turbo roundabouts are not different from traditional roundabouts. The decision of whether to

add separated bicycle facilities at turbo roundabouts depends on factors such as bicycle volume, the presence of

existing bicycle facilities, traffic volume, the complexity of the roundabout, adjacent infrastructure, land use, and

right-of-way availability. The following factors can be considered to accommodate bicyclists at a turbo

roundabout (2, 14):

1. Keeping turbo roundabout radius small to reduce vehicle speeds, which can make bicyclists more

comfortable.

2. Terminating bicycle lanes before the edge of the circular way and crosswalks with enough length

remaining for bicyclists to merge into traffic.

3. Introducing bicycle lanes on exit legs downstream of crosswalks.

4. If bicyclists share the sidewalk, designing sidewalks to meet shared use path width requirements.

5. If the intent is for bicyclists to cross at-grade on approaches, whether on a designated crossing or on a

pedestrian crosswalk, a pavement-level cut-through of the splitter island can be provided. The cut-through

can be designed to include a chicane to encourage a two-stage crossing for bicyclists and provide more

time for approaching drivers to identify crossing bicyclists. This is a commonly used treatment in

Netherlands.

Motorcyclists

Between 2005 and 2013, a total of 46 fatal crashes were known to have occurred at roundabouts in the U.S. and

among those 21 involved a motorcycle (49). Motorcycle safety at roundabouts can be impacted by the presence

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of raised lane dividers and curbing, surface friction, pavement markings, drainage, sight distance (especially rider

conspicuity), radius, the roadside environment, and surface conditions. Specific concerns for motorcyclists in

turbo roundabouts are the raised truck apron and lane divider. Sloped curbing with minimal vertical reveal can be

provided for a safer environment for motorcycles compared to vertical or rolled curbing. Supplemental signage

alerting motorcyclists to these elements of turbo roundabouts can also be provided (2).

Freight/Large Trucks

As vehicles aren’t allowed to change lanes within a turbo roundabout, it is critical to provide sufficient space for

large vehicles to complete the movements/turning. In European design guidelines for turbo roundabouts, the

dimension of the design vehicle is considered so that the design vehicle does not track into adjacent lanes (16),

which are not sufficient in the U.S. as trucks are larger in the U.S. compared to Europe. Various design guidelines

for multilane roundabouts in the U.S., such as NCHRP 672 (14), Washington State Department of Transportation

Design Manual (50), and South Carolina Department of Transportation (51), allows large trucks to use the whole

width of the circulatory roadway to negotiate the roundabout. A raised lane divider is not a practical option due

to repeated strikes by the larger vehicles. Agencies can allow design vehicles to track across multiple lanes within

turbo roundabouts to avoid this problem. Large trucks entering the inside lane of turbo roundabout from an

approach need a wider opening to accommodate their larger swept paths. When a raised lane divider option is

used, a traversable, demarcating feature can be provided at the origin of the raised divider to ease the entrance of

larger vehicles (2). A central truck apron is provided in turbo roundabouts to help larger vehicles to navigate the

intersection. Aprons can also be provided on the perimeter of the turbo roundabout to provide more turning space

for large vehicles (2).

Location Considerations

Site characteristics that can influence the feasibility of a turbo roundabout alternative include right-of-way

limitations, intersection skewness, winter maintenance needs, adjacent traffic generators or sites that require pre-

emption, and downstream bottlenecks. Additional detail on this matter can be found in the NCHRP Report 672

(14). Turbo roundabouts may be considered at an intersection where traffic demand indicates the need for a

multilane roundabout (2).

Design Considerations

The geometric design of a turbo roundabout depends on the desired capacity and the desired characteristics of a

design vehicle’s horizontal swept path. The projected demand and the approach roadway cross-sections determine

the number of lanes/lane arrangement, which dictate the type of turbo roundabout to be built. After selecting the

type, a horizontal swept path analysis of the design vehicle is done to decide on lane width and other lane width-

related considerations (e.g., right-of-way, considerations for all vehicle types and users). The turbo roundabout

type and lane widths are combined to construct the turbo block, which guides the geometric design of the

circulatory roadway (2).

Horizontal Design

Turbo Block: The spiral alignment of a turbo roundabout is generated from the “turbo block,” which is a series

of circular arcs with centers located at various points along a reference line known as a “translation axis.” The

turbo block consists of arcs, which represent the inner and outer edges of each lane. The inner radius of the turbo

block represents the radius of the central island, and it is selected based on the anticipated size of the turbo

roundabout. The shift along the translation axis from the center is the width of the lane represented by the arc.

The turbo block and angle of the translation axis differ for each turbo roundabout type. Figure A.5 is a sample

turbo block for a basic turbo roundabout with the major roadway oriented in the East-West direction.

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Figure A.5: Sample turbo block for a basic turbo roundabout (2)

The turbo block is defined by the characteristics shown in Figure A.5. The center point (CG) is the intersection

of the approach centerlines. The orientation of the translation axis is defined in relation to the major road

approaches. Assuming the major road is oriented in East-West direction (i.e., x-axis) in Figure A.5, the right side

of the translation axis is rotated 57.5 degrees around the center below the x-axis for a four-leg intersection, and

the left side of the translation axis is rotated 65 degrees around the center below the x-axis for a three-leg

intersection (2, 4, 24). The angle of rotation for the translation axis can be adjusted to provide smooth, spiraled

vehicle paths for all vehicle movements. TR1, TR2, TR3, and TR4 are the radius of the circles. TR1 is the radius

of the inside edge of the inside roadway. TR2 is the outside edge of the inside roadway; with the difference

between TR2 and TR1 equal to the width of the inside travel lane plus additional width for the edge lines

delineating the raised lane divider. TR3 is the inside edge of the outside roadway. The difference between TR2

and TR3 is the width of the lane divider. TR4 is the outer edge of the outside roadway.

Another important key set of dimensions defining the turbo block is the distances between the center points of

the arcs. The circles corresponding to the four radiuses are split along the translation axis, and the resulting arcs

are slide along the translation axis in opposing directions by half the distance defined as the shift. The shift is the

distance between the centers of the arcs. The shift can differ for the TR1 centers and the TR2, TR3, and TR4

centers if the inside roadway width is different than the outside roadway width. The shift for the TR1 centers (Δʋ

in Figure A.5) is equal to the difference between the inside edge of the inside roadway and the inside edge of the

outside roadway (also the difference between the values used for TR3 and TR1). The shift for the TR1 centers is

achieved by sliding the two arcs defined by TR1 in opposing directions away from CG, each by Δʋ/2. Based on

the international practice, Δʋ/2 ranges from between 8.5 and 9.5 feet (for total shifts ranging between 17 and 19

feet), as shown in Figure A.5. The shift for the TR2, TR3, and TR4 centers (Δu in Figure A.5) is the distance

between the outside edge of the inside roadway and the outside edge of the outside roadway (also the difference

between the values used for TR4 and TR2). The shift for the TR2, TR3, and TR4 centers is achieved by sliding

the arcs defined by TR2, TR3, and TR4 in opposing directions away from CG by Δu/2, as shown in Figure A.5.

This value (Δu/2) typically ranges from between 7.5 and 8.5 feet (for a total shift of 15 to 17 feet). If the inside

and outside roadways have the same width, the shift value for all radii are the same (i.e., Δʋ = Δu). Internationally,

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the radius (TR1, TR2, TR3, and TR4) for basic turbo roundabouts have ranged as follows:34 to 66 feet for TR1;

52 to 82 feet for TR2; 53 to 83 feet for TR3; and 70 to 100 feet for TR4. The nominal diameter of the turbo

roundabout is twice the value TR4 plus the width of the TR2/3/4 shift, Δu. Assuming a shift of 15 feet, the

inscribed circle for basic turbo roundabouts ranges from 155 feet to 215 feet.

Lane and Roadway Width: The width of each lane of a turbo roundabout is determined by a horizontal swept path

analysis of the design vehicle. The inside lane is often wider than the outside lane to compensate for the design

vehicle maneuvering a smaller radius. Inside lane width ranges from between 14 and 16 feet, while outside lane

width ranges from between 13 and 14.5 feet. The inner roadway width (TR2-TR1), including the inside and

outside edge line pavement markings, ranges from between 16 and 18 feet. The outer roadway width (TR4 -TR3),

including the inside and outside edge line pavement markings, ranges from between 15 and 16.5 feet (2, 4, 24).

Central Island: The central island is the innermost radius of the turbo block (TR1) and consists of a traversable

portion (i.e., mountable apron) and a non-traversable portion. The non-traversable portion is typically used for

signage. Cutouts are provided in the central island to introduce the inside lane of the turbo roundabout on the

applicable approaches. These cutouts can be curved or flat. Objects placed on the central island should not restrict

sight distance along the circulatory roadway (2).

Lane Divider: Lane divider between each circulating lane is an important feature of the turbo roundabout. It can

be of two types- raised and not raised. A raised lane divider is often introduced with a traversable, demarcating

feature to allow turning by large trucks. Turbo roundabouts without raised lane dividers are implemented to

facilitate motorcyclists and snow plowing operations (4). Alternatives to the raised lane divider include striping

and colorized or textured pavement, milled rumble strips or rumble stripes, a double solid white lane (17).

Approach Geometry: Turbo roundabouts are constructed with radial approaches, which reduces the changes to

the alignment along the approach roadway and maintaining exit curvature that encourages drivers to maintain

slower speeds through the exit of the roundabout. Turbo roundabouts are built with little or no flare or deflection

and smaller entry radius. Therefore, the angle between entering traffic and circulating traffic is larger (closer to a

perpendicular entry) for a turbo roundabout than for other multilane roundabouts. This approach geometry is

based on the premise that it will be clear to drivers that they are approaching an intersection that should be

negotiated at lower speeds (4). Potential disadvantages include drivers errantly hitting the central island, making

wrong-way left turn maneuvers to enter the roundabout, and making wrong-way exit maneuvers into entrance

approach lanes (14). Published literature emphasizes the importance of a roundabout directional arrow sign,

placed in the central island in the line of sight of approaching drivers, that directs drivers to turn right and increases

the conspicuity of the central island and the need for a forgiving design of the central island and sign in the case

that either is struck (2). Turbo roundabout entry radius ranges from 39 to 50 feet (16, 24) while the multilane

roundabouts in the US are designed with entry radius exceeding 65 feet, and even single-lane roundabouts have

entry radii ranging from 50 to 100 feet (14).

Sight Distance and Visibility

Adequate stopping and decision sight distance should be provided for all users at all approaches of the turbo

roundabout. NCHRP Report 672 provides guidelines for evaluating sight distance and visibility at roundabouts

(14).

Signage and Pavement Markings

Signage and pavement markings on the approaches, especially for lane selection, are critical for motorists to

identify and select their desired lane before entering the turbo roundabout. MUTCD and NCHRP Report 672,

describe applications of lane control signage for roundabout approaches (14, 17). Lane control signage can be

supplemented using pavement marking arrows (2). Signage can also direct pedestrians and bicyclists to designated

facilities, drivers to their desired lanes, and communicate the presence of raised curbing, such as a raised lane

divider (if one is used). If the lane divider includes grooved, textured, or brick pavements, consideration can be

given to including sign W8-15 to warn road users of its presence. Pavement markings shall be used to delineate

the edges of the approach and circulatory lanes. Additionally, supplemental delineation can be achieved using

reflectors or light-emitting diodes (LEDs) to illuminate the edges of the apron and lane dividers (2, 17).

Pedestrian Design Treatments

Pedestrian accommodations in turbo roundabouts are similar to modern roundabouts. Crossings should be kept at

the perimeter of the intersection, with crosswalks and splitter islands on the approaches to facilitate two-stage

20

crossings. All sidewalks, crosswalks, and curb ramps should be accessible to and usable by pedestrians with

disabilities for ADA compliance. The crosswalk should be placed far enough (minimum of 20 feet, or one vehicle-

length) from the circulatory roadway so that a motorist can exit the roundabout and then stop before reaching any

potential pedestrians in the crosswalk (2, 14).

Bicycle Design Treatments

Bicycle guidance for turbo roundabouts is also the same as for modern roundabouts. A bicyclist can either mix

with motor vehicle traffic or, when available, utilize separated facilities based on the bicyclist volume, traffic

volume, complexity of the roundabout, adjacent infrastructure, land use, and available right-of-way. In the

Netherlands, separate bicycle paths outside of the roundabout are recommended for turbo roundabouts where

possible (2, 24).

Vertical Design

Vertical alignment considerations in turbo roundabouts are the same as modern roundabouts. The geometry

should not restrict sight distance throughout the intersection area, including decision sight distance on the

approaches when selecting lanes, stopping sight distance on the approach and on the circulatory roadway, and

intersection sight distance at the entrances to the circulatory roadway (2).

Lighting

The proper lighting should be done to improve the visibility of the middle island and raised lane divider (24).

Lighting should also be provided to give adequate visibility for pedestrian and bicycle facilities, especially

crossings, and negative contrast lighting and shadowing should be avoided (2,15).

Landscaping

Landscaping should be limited to the non-traversable portion of the central island and not blocking the stopping

sight distance around the circulatory roadway. If sprinklers are used to maintain landscaping, designers should

consider the impacts of irrigation runoff onto the circular roadway, as unexpected wet pavement can introduce

another potential safety risk to users of the intersection (2, 52).

Other Design Considerations

Additional design considerations, such as bypass lanes, access management, at-grade rail crossings, evacuation

routes, and bus stops, should be addressed the same as they are for modern roundabouts. Specific guidelines for

these issues can be found in NCHRP Report 672 (2, 14).

Comparison to United States Roundabout Design Principles

NCHRP Report 672 describes six overarching principles that inform the design of roundabouts (14). Table A.1

describes the principles and the manners in which they are addressed in turbo roundabouts (2).

Table A.1: Roundabout design principles compared with turbo roundabout (2)

Design Principles from NCHRP Report

672 (14)

Addressed in Turbo Roundabouts

“Provide slow entry speeds and consistent

speeds through the roundabout by using

deflection.”

International practices of a perpendicular entry and smaller

radii of the right turns on entry are intended for slow vehicle

entry speeds.

“Provide the appropriate number of lanes

and lane assignment to achieve adequate

capacity, lane volume balance, and lane

continuity.”

Turbo roundabout variants are available for a range of

traffic demand. International research suggests basic turbo

roundabouts have similar capacities as multilane

roundabouts with two entry and two circulating lanes.

“Provide smooth channelization that is

intuitive to drivers and results in vehicles

naturally using the intended lanes.”

The spiral lane markings and lane dividers provide intuitive

messaging to drivers on lane selection, lane-keeping, and

the appropriate maneuvers from each lane.

“Provide adequate accommodation for

design vehicles.”

As with modern multilane roundabouts, lane width

decisions for turbo roundabouts are informed by a

horizontal swept path analysis of the design vehicle along

with other lane width-related considerations (e.g., right-of-

way, performance for all vehicle types and users).

21

Additionally, aprons are provided on the central island and,

as necessary, on the perimeter of the roundabout to provide

additional space.

“Design to meet the needs of pedestrians

and cyclists.”

Pedestrian and bicycle accommodations for turbo

roundabouts do not differ from modern multilane

roundabouts.

“Provide appropriate sight distance and

visibility for driver recognition of the

intersection and conflicting users.”

Signage is placed far enough in advance of the roundabout,

so road users are aware of the approaching intersection and

the need to select their appropriate lane before entering the

roundabout. The roundabout directional arrow sign on the

central island increases driver recognition of the

roundabout.

Safety Performance of Turbo Roundabout

As turbo roundabouts are still an emerging concept, international safety studies based on an analysis of crash data

are limited and not yet available based on any installation in the US. Seven intersections, including signalized,

yield-control, and old-style rotary types, were converted to a turbo roundabout in the Netherlands and found an

82% percent reduction in the number of injury crashes (4). A Polish research found that turbo roundabouts with

a raised lane divider experience a lower crash frequency than those with paint stripes only, and in both cases the

researchers observed lower severity crash outcomes (18). Surrogate safety measures based on microscopic traffic

simulations (e.g., time-to-collision, vehicle speeds, vehicle conflicts, incorrect movements, and incorrect paths)

have also indicated that turbo roundabouts are likely to experience less frequent and less severe crashes than

multilane roundabouts due to the fewer conflict points within the roundabout and the lower speeds required to

navigate the smaller radius (19, 20, 21, 22, 23).

Table A.2. The conclusions from international scientific researches on road safety on turbo roundabouts

(18).

Country Findings

Holland The risk of injury following a road traffic accident or collision on turbo roundabouts

is 80% lower than in other types of multi-lane roundabouts. A slightly lower reduction

of the injury risk on turbo roundabout (by 70%) is expected compared to single-lane

roundabouts.

Turbo roundabouts are 70% safer than intersections without traffic signals, 50% safer

than intersections with traffic signals.

Italy A degree of improvement in road safety on the turbo roundabouts depends on the

traffic organization, intensity, and directional structure of traffic and ranges from 40 to

50% reduction in traffic accidents.

After the reconstruction of three intersections into turbo roundabouts, road safety

conditions improved while driving speed reduced considerably.

Slovenia No traffic accidents with serious consequences were recorded (analysis was carried out

in one location).

Slovakia Turbo roundabouts are characterized as a solution with a very high level of safety

improvement.

Colombia Turbo roundabouts exhibit improvement in road safety by 22%.

Poland

After the reconstruction of the roundabout into a turbo roundabout (with lane dividers

in the form of a single continuous line), the number of collisions was declined by 80%.

22

• In general, high level of road safety was recorded at intersections. No fatalities were

reported during the period of the analysis. Property damage only (PDO) was

predominant (95.98%) among the recorded traffic accidents.

• The most frequent traffic accidents were rear-end collisions, driving into an

obstacle, side-impacts, and overturning.

• The most frequent causes of the traffic events were not-giving way, the excessive

speed with respect to the conditions on the road, lack of safe distance from the

preceding vehicle, illegally changed lanes, and illegal overtaking.

In Portugal, the first turbo roundabout was built in Coimbra (Choupal Rbt), replacing an existing single-lane

roundabout (19). Before implementation, a study was conducted to evaluate the safety and operational

performance of the prospective turbo roundabout to be constructed. For comparison, three layouts of similar

implantation areas were modeled in Aimsun – the existing single-lane solution, a two-lane alternative, and a turbo-

roundabout. All three models were simulated with the current traffic demand (23816 veh/d). The safety analysis

was done by SSAM, and the results presented in Table A.3, and the layouts of the three models with SSAM results

are shown in Figure A.6. The two-lane roundabout showed the worst performance both in the number and severity

of conflicts, mostly due to the weaving maneuvers. The turbo-roundabout, compared with the single-lane solution,

had fewer conflicts, but these are more severe due to the increased angle between entry and circulating trajectories.

Turbo roundabout performed better than tow-lane roundabout in terms of safety performance.

Figure A.6. SSAM results for the Choupal Rbt: graphical display of conflicts, colored by relative speed as

the proxy for the accident severity (19).

Table A.3. SSAM results for the Choupal Rbt, Coimbra, Portugal (19) Roundabout type (conflicts/day) Relative speed (m/s)

< 5 5 - 10 > 10

Single-lane roundabout 420 46% 44% 10%

Two-lane roundabout 539 49% 37% 14%

Turbo roundabout 301 51% 36% 13%

23

Another study on turbo roundabout safety analysis was performed using the VISSIM microsimulation model of

a two-lane roundabout in Bogota (20). With the known traffic demand, a basic turbo roundabout was designed,

simulated, and calibrated. Vehicular trajectory files were obtained from calibrated simulation models, which were

analyzed by SSAM to estimate traffic conflicts. The number of conflicts in the two-lane roundabout and the turbo-

roundabout are summarized in Table A.4. The total number of conflicts in the turbo-roundabout was 72% lower

than in the two-lane roundabout.

Table A.4 - Comparison between intersections based on the number of conflicts (20)

Parameter Total Rear-end conflicts Crossing conflicts

Angle Threshold - 0° - 45° 45° - 135°

Two-lane roundabout 338 209 129

Turbo-roundabout 96 44 52

Difference 242 165 77

Change -72% -79% -60%

Operational Performance of Turbo Roundabout

Like modern roundabouts, turbo roundabout capacity is measured at the approach level. International studies

suggest that basic turbo roundabouts have similar capacities as multilane roundabouts with two entry and two

circulating lanes. One study in the Netherlands estimated a capacity for a basic turbo roundabout design of

approximately 3,500 pc/h for all entries combined, assuming conflicting traffic volumes between 1,900 and 2,100

pc/h (24). Turbo roundabout exhibits lower speeds than a two-lane roundabout and lower speed than a single lane

roundabout with an inner radius less than 15 meters (Figure A.7).

Figure A.7: Speed comparison between types of the roundabout with a splitter island width of 7 m (24)

For estimating turbo roundabout capacity, gap-acceptance models that consider critical headway, critical follow-

up time, and conflicting traffic appear to be adequate. A study in Poland found the Highway Capacity Manual

(HCM) capacity models for roundabouts produced capacity estimates for Polish turbo roundabouts with

reasonable accuracy (25). Therefore, the roundabout capacity models of the HCM are likely to represent

reasonable capacity estimates for turbo roundabout approaches with up to two lanes (2).

Costs

As of today, no turbo roundabouts have been constructed in the US. As turbo roundabouts are similar to multilane

roundabouts, they are expected to have similar types of costs. Turbo roundabouts may vary slightly from multilane

roundabouts in the required right-of-way. A radial entry with no flare and smaller entrance radius requires a larger

swept path for large vehicles, which will lead to a wider circular roadway than for a comparable multilane

roundabout. However, there may not be significant changes to the alignment of the approach roadway given the

entry geometry of the turbo roundabout (2).

24

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25

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26

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27

12. APPENDIX B: CVs

Kakan Chandra Dey, PhD, PE

Assistant Professor

Department of Civil and Environmental Engineering

West Virginia University, Morgantown, WV 26506

Tel: 304-293-9952, Email: kakan.dey@mail.wvu.edu

EDUCATION

▪ Doctor of Philosophy in Civil Engineering, May 2014

Clemson University, South Carolina; Emphasis: Transportation Systems

▪ Master of Science in Civil Engineering, May 2010

Wayne State University (WSU), Michigan; Emphasis: Transportation

Engineering

▪ Bachelor of Science in Civil Engineering, June 2005

Bangladesh University of Engineering & Technology (BUET), Bangladesh

PROFESSIONAL LICENSE

Professional Engineer, 2018-

West Virginia State Board of Registration for Professional Engineers

APPOINTMENTS

▪ Assistant Professor (August 2016- Present)

Department of Civil and Environmental Engineering

West Virginia University, WV

▪ Project Manager, NSF US Ignite Project (January 2016 – August 2016)

Clemson University, Clemson, SC

▪ Postdoctoral Fellow (May 2014 – August 2016)

Connected and Automated Vehicle Technology Group

Glenn Department of Civil Engineering, Clemson University

MAJOR ACHIEVEMENTS

▪ George N. Saridis Best Transactions Paper Award 2017, IEEE Transactions

on Intelligent Transportation Systems

▪ ASCE ExCEEd Teaching Workshop Fellowship 2017

▪ Distinguished Postdoctoral Fellowship award, Clemson University 2016

▪ Two research projects I worked were selected as High Value Research

Project by the AASHTO Research Advisory Committee in 2014 and 2012

RESEARCH INTERESTS

▪ Intelligent Transportation Systems (ITS)

▪ Connected and Autonomous Vehicle Technology

▪ Data Analytics for Connected Transportation Systems

▪ Artificial Intelligence for Connected Vehicle Applications

▪ Cyber-Physical Systems

▪ Sustainability and Resiliency in Transportation

28

▪ Traffic Safety, Traffic Simulation

SELECTED PEER-REVIEWED JOURNAL PUBLICATIONS (Total 903 citations as of

December 29, 2020 Source: Google Scholar) * my graduate students, ** corresponding author

[1] *Ahmed, S., Dey, K.** (2020) Resilience modeling concepts in

transportation systems: a comprehensive review based on mode, and

modeling techniques. Journal of Infrastructure Preservation and

Resilience 1, 8 https://doi.org/10.1186/s43065-020-00008-9

[2] He, Y., *Rahman, M. T., Akin, M., Wang, Y., **Dey, K., and **Shi, X.

(2020). Connected Vehicle Technology for Improved Multimodal Winter

Travel: Agency Perspective and a Conceptual Exploration. Sustainability,

12(12), 5071.

[3] Das, S., Dutta, A., Dey, K., Jalayer, M., and Mudgal, A. (2020) “Vehicle

involvements in hydroplaning crashes: applying interpretable machine

learning,” Transportation research interdisciplinary perspectives, 6,

100176.

[4] *Ahmed, S., Dey, K., and Fries, R., (2019) “Evaluation of Transportation

System Resilience in the Presence of Connected and Automated Vehicles,”

Transportation Research Record, 2673(9), 562-574, 0361198119848702.

[5] Khan, Z., Khan, S. M., Dey, K., and Chowdhury, M. (2019) “Development

and Evaluation of Recurrent Neural Network-Based Models for Hourly

Traffic Volume and Annual Average Daily Traffic

Predictions,” Transportation Research Record, 2673(7), 489-503,

0361198119849059.

[6] Khan, S. M., Mitchell, J., Chowdhury, M., Dey, K., and Huynh, N. (2018)

“Operational analysis of a connected vehicle-supported access control on

urban arterials,” IET Intelligent Transport Systems, 12(2), 134-142.

[7] Rahman, M., Chowdhury, M., Dey, K., Islam, M. R., and Khan, T. (2017),

“Evaluation of Driver Car-Following Behavior Models for Cooperative

Adaptive Cruise Control Systems,” Transportation Research Record:

Journal of the Transportation Research Board, Vol. 2622, 84-95.

[8] Bhavsar, P., Das, P., Paugh, M., Dey, K., and Chowdhury, M. (2017),

“Risk Analysis of Autonomous Vehicles in Mixed Traffic Streams,”

Transportation Research Record: Journal of the Transportation Research

Board, Vol. 2625, 51-61.

[9] Khan, S. M., Dey, K., and Chowdhury, M. (2017), “Real-Time Traffic

State Estimation with Connected Vehicles,” IEEE Transactions on

Intelligent Transportation Systems. Vol 18, Issue 7, 1687 - 1699

[10] Dey, K., Rayamajhi, A., Chowdhury, M., Bhavsar, P., (2016)

“Vehicle-to-Vehicle (V2V) and Vehicle-to-Infrastructure (V2I)

Communication in Heterogeneous Wireless Network - Performance

Evaluation,” Transportation Research Part C: Emerging Technologies,

Vol. 68, 168-184.

[11] Li, Z., Dey, K., Chowdhury, M., and Bhavsar, P., (2016) “Connected

Vehicle Technology Application for Dynamic Routing of Electric Vehicles

in an Inductively Coupled Power Transfer Environment,” IET Intelligent

Transport Systems Journal, DOI# 10.1049/iet-its.2015.0154

[12] Dunning, A., Dey, K., and Chowdhury, M., (2015) “Review of

Transportation Infrastructure Deterioration and Recovery Policies due to

Overweight Truck and a Case Study on Stakeholders’ Perspectives,”

ASCE Journal of Infrastructure Systems. DOI: 10.1061/(ASCE)IS.1943-

555X.000029

29

[13] Dey, K., Yan, L., Wang, X., Wang, Y., Shen, H., Chowdhury, M., Yu,

L., Qiu, C., and Soundararaj, V., (2015) “A Review of Communication,

Driver Characteristics and Controls Aspects of Cooperative Adaptive

Cruise Control (CACC),” IEEE Transactions on Intelligent Transportation

Systems, Published online, DOI: 10.1109/TITS.2015.2483063. Recipient of

the George N. Saridis Best Transactions Paper Award 2020

[14] Dey, K., Chowdhury, M., Wiecek, M., and Dunning, A., (2014)

“Tradeoff Analysis for Offsetting Overweight Truck Damage Costs to

transportation Infrastructure,” ASCE Journal of Transportation

Engineering, Vol. 141(7), 04015008

[15] Dey, K., Chowdhury, M., Pang, W., Putman, B., and Chen, L., (2014)

“Estimation of Pavement and Bridge Damage Costs Due to Overweight

Trucks,” Transportation Research Record, Vol. 2411, pp. 62-71

[16] Davis-McDaniel, C., Chowdhury, M., and Pang, W., and Dey, K.,

(2013) “Fault-tree model for identification of causal factors and risk

assessment of bridge failure,” ASCE Journal of Infrastructure Systems,

Vol. 19(3), pp. 326–334

Under

Review

[1] Rahman, M.T., Dey, K., Martinelli, D.R., and Mishra, S., “Modeling and

Evaluation of a Ridesharing Matching System from Multi-Stakeholders’

Perspective”

[2] Dey, K., Rahman, M.T., Martinelli, D.R., Das, S., and Williams, A.M.,

“Left Turn Phasing Selection Considering Vehicle to Vehicle and Vehicle

to Pedestrian Conflicts”

[3] Rahman, M.T., Dey, K., Das, S, Sherfinski, M., “Sharing the Road with

Autonomous Vehicles: A Qualitative Analysis of the Perceptions of

Pedestrians and Bicyclists”

BOOKS

Chowdhury, M., Apon, A., Dey, K. [Editors], Data Analytics for Intelligent

Transportation Systems, Elsevier, 2017, eBook ISBN: 9780128098516,

Paperback ISBN: 9780128097151

BOOK CHAPTERS

[1] Dey, K., Fries, R., and Ahmed, S. (2018). Future of Transportation Cyber-

Physical Systems–Smart Cities/Regions. In Transportation Cyber-

Physical Systems (pp. 267-307). Elsevier.

[2] Khan, S. M., Ngo, L. B., Morris, E. A., Dey, K., and Zhou, Y. (2017).

Social Media Data in Transportation. In Data Analytics for Intelligent

Transportation Systems (pp. 263-281).

PROJECT REPORTS

[1] Bhavsar, P., Dey, K., Chowdhury, M., and Das, P. (2017) “Risk analysis of

autonomous vehicles in mixed traffic streams,” Final Report University

Transportation Research Center-Region 2, UTRC/RF Grant No: 49198-28-

27

[2] Chowdhury, M., Putman, B., Pang, W., Dunning, A., Dey, K., and Chen,

L., (2013) “Study of rate of deterioration of bridges and pavements as

affected by trucks,” South Carolina Department of Transportation, Final

Report FHWA-SC-13-05. AASHTO Research Advisory Committee

selected “High Value Research Project” in year 2014.

30

[3] Chowdhury, M., Ogle, J., Gowan, B., Tupper, L., Familian, S., and Dey, K.,

(2011) “The Relationship of South Carolina Damage Claims to Roadway

Engineering Safety Issues,” South Carolina Department of Transportation,

Final Report FHWA-SC-11-01. AASHTO Research Advisory Committee

selected “High Value Research Project” in year 2012.

[4] Savolainen, P., Dey, K., Ghosh, I., Karra, T., Lamb, A, (2009)

“Investigation of Emergency Vehicle Crashes in the State of Michigan,”

No. NEXTRANS Project No. 015WY01.

FUNDED PROJECTS (MOST RECENT)

[1] Center for Advanced Multimodal Mobility Solutions and Education

(CAMMSE), “Multimodal Connected Vehicle Pilot for Winter Travel,” in

collaboration with Washington State University, 2020-2021, My role: PI

at WVU

[2] Tennessee Department of Transportation, “Towards Sustainable Tourism

Transportation Systems and Services in Tennessee,” in collaboration with

University of Memphis, 2020-2022, My role: PI at WVU

[3] National Science Foundation, “Research Initiative: A Holistic Cross-

Disciplinary Project Experience as a Platform to Advance the Professional

Formation of Engineers,” 2019-2021, My role: PI

[4] South Dakota Department of Transportation, “Winter Maintenance Levels

of Service and Performance Measures,” 2019-202, My role: PI

[5] Ohio Department of Transportation, “Intersection Modifications Using

Modular Mini-Roundabout Methods,” in collaboration with Ohio

University, 2019-2020, My role: PI at WVU

[6] Tennessee Department of Transportation, “Investigation On Wrong-Way

Prevention Technologies And Systems,” in collaboration with University

of Memphis, 2019-2020, My role: PI at WVU

SELECTED SYNERGISTIC ACTIVITIES

▪ Project Panel member, Behavioral Traffic Safety Cooperative Research

Program, Transportation Research Board (TRB)- National Research

Council, 2019-2022

▪ Advisory Board Member, Center for Multimodal Mobility, USDOT Tier-1

UTC, 2017-2022

▪ Session Chair, “Lest in Truck Size and Weight Research,” In TRB 99th

Annual Meeting, to be held January 14, 2020, Washington, D.C.

▪ Session Chair, “Artificial Intelligence and Machine Learning Methods for

Transportation Applications, Part 1,” In TRB 98th Annual Meeting, to be

held January 14, 2019, Washington, D.C

31

Bhaven Naik, PhD, PE, PTOE, RSP.

Associate Professor

Department of Civil Engineering

Stocker Center 226

1 Ohio University, Athens OH 45701

Phone: +1 (740) 593-4151

Email: naik@ohio.edu.

PROFESSIONAL PREPARATION

2010 Doctorate. (Civil Eng. – Transportation major + Statistics minor); Univ. of Nebraska,

Lincoln, NE.

2004 Masters. (Civil Eng. – Transportation major); Univ. of Nebraska, Lincoln, NE.

2003 Bachelors. (Civil Eng.); Univ. of Nebraska, Lincoln, NE.

1997 Diploma (Civil Eng.); Copperbelt University, Kitwe, Zambia.

PROFESSIONAL REGISTRATION

Registered Professional Engineer – Nebraska (#E-15635) and Ohio (#PE.81951).

Registered Professional Traffic Operations Engineer (#4065).

Registered Road Safety Professional (#305).

APPOINTMENTS

Ohio University

Associate Professor – Department of Civil Engineering August, 2020 – Present

Assistant Professor – Department of Civil Engineering August, 2014 – August, 2020

University of Nebraska-Lincoln

Lecturer – Department of Civil Engineering January, 2013 – August, 2014

Post-Doctoral Research Associate, Mid-America Transportation Center January, 2011 – August, 2014

PUBLICATIONS AND PRESENTATIONS

Peer Reviewed Journal Papers (2014 to present)

2020

Walubita, L.F., Fuentes, L., Lee, S.I., Guerrero, O., Mahmoud, E., Naik, B., & Simate, G.S. Correlations and

Preliminary Validation of the Laboratory Monotonic Overlay Test Data to Reflective Cracking Performance of

In-Service Field Highway Sections. Journal of Construction and Building Materials, (In Press).

Barbieri, D.M. et al. Survey Data Regarding Perceived Air Quality in Australia, Brazil, China, Ghana, India,

Iran, Italy, Norway, South Africa, United States Before-and-After COVID-19 Restrictions. Data in Brief

Journal, (Accepted for publication, Aug 6, 2020).

El-Dabaja, S., McAvoy, D., & Naik, B. Alert! Automated Vehicle (AV) System Failure – Drivers’ Reactions to

a Sudden, Total Automation Disengagement. In: Stanton, N. (eds) Advances in Human Aspects of

Transportation. AHFE 2020, Advances in Intelligent Systems and Computing, 1212, pp.49-55.

Walubita, L.F., Fuentes, L., Faruk, A.N.M., Komba, J., Prakoso, A., & Naik, B. Mechanistic-Empirical

Compatible Traffic Data Generation: Portable WIM versus Cluster Analysis. Journal of Testing and

Evaluation, 48 (3), pp.2377-2392.

2019

32

Walubita, L.F., Fuentes, L., Prakoso, A., Rico Pianeta, L.M., Komba, J.J., & Naik, B. Correlating the HWTT

Laboratory Test Data to Field Rutting Performance of In-Service Highway Sections. Journal of

Construction and Building Materials, 236, pp.1-12.

Fuentes, L., Camargo, R., Martinez-Arguelles, G., Komba, J.J., Naik, B., & Walubita, L.F. Pavement

Serviceability Evaluation using Whole Body Vibration Techniques: A Case Study for Urban Roads.

International Journal of Pavement Engineering, 20, pp. 1-12.

Naik, B., Appiah, J., & Rilett, L.R. Are Dilemma Zone Protection Systems Useful on High Speed Arterials

with Signal Coordination? A Case Study. International Journal of Intelligent Transportation Systems

Research, pp.1-11.

Walubita, L.F., Faruk, A.N.M., Fuentes, L., Prakoso, A., Dessouky, S., Naik, B., & Nyamuhokya, T.P. Using

the Simple Punching Shear Test (SPST) for Evaluating the HMA Shear Properties and Predicting Field

Rutting Performance. Journal of Construction and Building Materials, 224, pp.920-929.

2018

Naik, B., Rilett, L.R. Appiah, J., & Walubita, L.F. Resampling Methods for Estimating Travel Time

Uncertainty: Application of the Gap Bootstrap. TRR 2672 (42), pp.137-147.

Walubita, L.F., Nyamuhokya, T.P., Komba, J.J., Tanvir, H.A., Souliman, M.I., & Naik, B. Comparative

Assessment of the Interlayer Shear-Bond Strength of Geogrid Reinforcements in Hot-Mix Asphalt.

Journal of Construction and Building Materials, 191, pp.726-735.

Walubita, L.F., Nyamuhokya, T.P., Naik, B., Holleren, I., & Dessouky, S. Sensitivity Analysis and Validation

of the Simple Punching Shear Test (SPST) for Screening HMA Mixes. Journal of Construction and

Building Materials, 169, pp.205-214.

Sperry, B.R., Mahmood, S., & Naik, B. Investigating Land Development and Traffic Composition at Rural

Interstate Highway Interchanges in Ohio. Journal of Transportation Engineering, Part A: Systems, 144(7).

2017

Sperry, B.R., Naik, B., & Warner, J.E. Current Issues in Highway-Railroad Grade Crossing Hazard Ranking

and Project Development. TRR 2608, pp. 19-26.

2016

Naik, B., Tung, L.W, Zhao, S., & Khattak, A.J. Weather Impacts on Single-Vehicle Truck Crash Injury

Severity. Journal of Safety Research, 58, pp.57-65.

Faruk, A.N., Liu, W., Lee, S.I., Naik, B., Chen, D.H., & Walubita, L.F. Traffic Volume and Load Data

Measurement Using a Portable Weigh-In Motion System: A Case Study. International Journal of

Pavement Research and Technology, 9(3), pp.202-213.

Appiah, J., Naik, B., Rilett, L.R., & Sorensen, S. Calibrating Truck Characteristics into Traffic

Microsimulation. Institute of Civil Engineers – Transport Journal, 169(4), pp.187-194.

2015

Faruk, A.N., Lee, S.I., Zhang, J., Naik, B., & Walubita, L.F. Measurement of HMA Shear Resistance Potential

in the Lab: The Simple Punching Shear Test. Journal of Construction and Building Materials, 99, pp.62-

72.

Eisele, W.L., Naik, B., & Rilett, L.R. Estimating Route Travel Time Reliability from Simultaneously Collected

Link and Route Vehicle Probe Data and Roadway Sensor Data. International Journal of Urban Sciences,

19(3), pp.286-304.

2014

Li, J., Oh, J., Naik, B., Simate, G., & Walubita, L.F. Laboratory Characterization of Cracking-Resistance

Potential of Asphalt Mixes Using Overlay Tester. Journal of Construction and Building Materials, 70,

pp.130-140.

Peer Reviewed Journal Papers (prior to 2014)

33

Appiah, J., Rilett, L.R., Naik, B., & Wojtal, R. (2013) Driver Response to an Actuated Advance Warning

System. ASCE Journal of Transportation Engineering, 139(5), pp.433-440.

Appiah, J., Rilett, L.R., Naik, B., & Sorensen, S. (2013) Calibration of Microsimulation Models for Advance

Warning Systems. Journal of Modern Traffic and Transportation Engineering Research 2(1), pp.41-47.

Appiah, J., Naik, B., Wojtal, R. & Rilett, L.R. (2011) Safety Effect of Dilemma-Zone Protection Using

Actuated Advance Warning Systems. TRR 2250, pp.19-24.

Naik, B., Appiah, J., Khattak, A.J., & Rilett, L.R. (2009) Safety Effectiveness of Offsetting Opposing Left

Turn Lanes: A Case Study. Journal of the Transportation Research Forum, 48(2), pp.71-82.

Peer Reviewed Conference Proceedings (2014 to present)

Hussein, F.F, Suer, G.A., & Naik, B. (2020) Travel Time Modeling Using Non-Linear Multi-Objective Fuzzy

Optimization Approach. In Proceedings of the International Conference on Transportation and

Development 2020: Planning and Development, Seattle, WA.

Hussein, F.F, Suer, G.A., & Naik, B. (2020) Development of Hybrid Hard Shoulder Running Operation

System for Active Traffic Management. In Proceedings of the International Conference on Transportation

and Development 2020: Traffic and Bike/Pedestrian Operations, Seattle, WA.

Albuquerque, F.D, Mohamed, H., Naik, B., Memon, A.A., & Basheerudeen, B. (2018) Development of

Methodology for Traffic Calming Measure Allocation. In Proceedings of the 6th Annual International

Conference on Architecture and Civil Engineering, Singapore.

Sperry, B.R, Naik, B., & Warner, J. (2017) Evaluation of Grade Crossing Hazard Ranking Models. In

Proceedings of the 2017 ASME/IEEE Joint Rail Conference, Philadelphia, PA.

Published Research Reports (all)

Naik, B., Matlack, G., Khoury, I., Sinha, G., McAvoy, D.S., Horn, A., & Gassaway, O. (2020) Effects of Tree

Canopy on Rural Highway Pavement Condition, Safety, and Maintenance: Phase II. Report No. FHWA/OH-

2020/17. Final Report to the Ohio Department of Transportation.

Naik, B., Matlack, G., Khoury, I., Sinha, G., & McAvoy, D.S. (2017) Effects of Tree Canopy on Rural Highway

Pavement Condition, Safety, and Maintenance: Phase I. Report No. FHWA/OH-2017/18. Final Report to

the Ohio Department of Transportation.

Naik, B., Che, D., Campbell, J., Zelinsky, R., Neef, S., Forcum, C., Cotter, M., & Hollis, J. (2017) Grounds

Improvement Initiative: General Mills Plant, Wellston Ohio. Final Report to General Mills Inc.

Sperry, B.R, Naik, B., & Warner, J. (2016). Evaluation of Grade Crossing Hazard Ranking Models. Report

No. FHWA/OH-2016/10. Final Report to the Ohio Department of Transportation.

Stolle, C.S., Rilett, L.R., Faller, R.K., Reid, J.D., Jones, E.G., Holloway, J.C., & Naik, B. (2014) Evaluation of

Speed Table Test No. ST-1 and CARSIM Model Validation. Report No. TRP-03-307-14. Final Report to

the Air Force Civil Engineer Center (AFCEC) and Surface Deployment and Distribution Command

Transportation Engineering Agency (SDDCTEA).

Stolle, C.S., Rilett, L.R., Faller, R.K., Reid, J.D., Jones, E.G., Holloway, J.C., & Naik, B. (2014) Passive Safety

Measures: Speed Hump and Speed Table Optimization Using CARSIM. Report No. TRP-03-305-14.

Confidential Draft Report to the Air Force Civil Engineering Center (AFCEC) and Surface Deployment and

Distribution Command Traffic Engineering Agency (SDDCTEA).

Naik, B., & Appiah, J. (2014). Dilemma Zone Protection on High-Speed Arterials. Report No. MATC-UNL

055.

Appiah, J., Naik, B., & Sorensen, S. (2012). Calibration of Micro-simulation Models for Multimodal Freight

Networks. Report No. MATC-UNL 429.

Appiah, J., Naik, B., Rilett, L.R., Chen, Y., & Kim, S. (2011). Development of a State-of-the-Art Traffic

Micro-simulation Model for Nebraska. Report No. SPR-1(06)P584.

Khattak, A.J., & Naik, B. (2006). The Use of Raised Pavement Markings in Work Zone Applications: A

Synthesis of Practice. Final report to the Midwest Smart Work Zone Deployment Initiative, Kansas

Department of Transportation.

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Khattak, A. J., Naik, B., and Kannan, V. (2004) Safety Evaluation of Left-Turn Lane Line Width at

Intersections with Opposing Left Turn Lanes. Report No. SPR-P1(03)P554.

FUNDED RESEARCH AND GRANTS

Principal Investigator

Intersection Modifications Using Modular Mini-Roundabout Methods. For the Ohio’s Research Initiative for

Locals/Ohio Department of Transportation, 2019/20 – $93,179.07. Status: On-going.

Effects of Tree Canopy on Pavement Condition, Safety, and Maintenance – Phase II. For the Ohio Department

of Transportation, 2017/19 – $348,946.36. Status: On-going.

Proposed Grounds Improvement Initiative for the General Mills Wellston, Ohio Plant. For General Mills Inc.,

2017/18 – $29,421.00. Status: Completed.

Effects of Tree Canopy on Pavement Condition, Safety, and Maintenance – Phase I. For the Ohio Department of

Transportation, 2016/17 – $72,683.67. Status: Completed.

Co-Principal Investigator

Enhance ODOT’s Highway Friction Management Program. Engineering Research Services – Task 6 for the

Ohio Department of Transportation, 2020 – $34,786.84. Status: On-going.

Target Gaps in the Automated Driving Systems’ Dataset: Rural Environments, Understudied Applications,

Transparent Methods. For the Ohio Department of Transportation/US Department of Transportation, 2020/22 –

$162,349.00. Status: On-going.

Design Review of Kabul-Logar Road in Afghanistan. For the Ministry of Public Works, Islamic Republic of

Afghanistan, 2019/20 – $169,767.69. Status: On-going.

A Novel Smart Fluid Filled Barrier for Crash Cushion and Attenuators. For the Ohio Development Services

Agency, 2019/20 – $100,000.00. Status: On-going.

Afghan National Laboratories. For the Ministry of Public Works, Islamic Republic of Afghanistan, 2017/18 –

$3,029,001.89. Status: On-going.

Evaluation of Grade Crossing Hazard Ranking Models. For the Ohio Department of Transportation, 2015/16 –

$80, 068.15. Status: Completed.

PROFESSIONAL ACTIVITIES

▪ Committee Member, Transportation Research Board Standing Committee on: Roadside Maintenance

Operations (AKR20).

▪ Member, American Society for Civil Engineers (ASCE).

▪ Member, Institute for Transportation Engineers (ITE).

▪ Member, Transportation and Development Institute (T&DI).

▪ Member, American Society of Engineering Education (ASEE).

▪ Member, Technical Committee for the International Conference on Building Materials & Engineering.