Virginia Statewide Roundabout Guidance (Transportation Research Board)

VirginiaStatewide Roundabout Guidance

TRB 4th International Conference on RoundaboutsApril 17, 2014

Andy Boenau

Chris Tiesler

VirginiaAndy Boenau

1.BackgroundPart

Statewide Roundabout Guidance

Option A = familiar throughout the U.S.; lots of death & destruction

Option B = familiar throughout the world; lots of life & prosperity

Intersection Design Options

“We connect land use

(said every DOT everywhere)

and transportation.”

Virginia DOT Transportation & Land Use Publications

“ensuring the

connectivity of pedestrian

networks”

“fundamental modes”

“enhance quality”

“…[roundabout] should be consideredthe Department’s

preferred alternative…”

Virginia Policy

If feasible, then preferred.

Why?

If feasible, then preferred.

Why?

Because we want more people to live!

Since single-lane roundabouts are thesafest form of at-grade intersection,

for pedestrians, bicyclists, and motorists!why aren’t there more

in Virginia?

Institutional bias

stat

e ag

enci

es

polit

icia

nsneighbors

consultants

and the fear of change.

Illustration of the anti-roundabout bias…

Roundabout1.Yield to traffic already in roundabout.

Traffic Signal1. If the signal is a red ball, come to a complete stop

a) After stopping, you may turn right but must yield to oncoming traffic; except if the sign says "NO TURN ON RED", you cannot

b) After stopping, you may turn left on red from a one-way street onto a one-way street but must yield to oncoming traffic

2. If the signal is a green ball

a) you may go straight or turn right, but only if the way is clear - you must yield to vehicles still in the intersection

b) you may turn left but must yield to oncoming traffic

3. If the signal is a yellow ball

c) you may go straight or turn right

d) you may turn left but must yield to oncoming traffic

4. If there is one signal head for several lanes, it applies to all those lanes; if there is a signal head for each lane, each lane is governed by its own signal head; and if there are multiple heads but not as many as there are lanes, generally a head centered above a lane governs that lane, a single head located above the line dividing two lanes governs both lanes, and a single head centered above three lanes governs all three lanes

5. If the signal for your lane is a red arrow pointing left or right, come to a complete stop

a) After stopping, you may turn right on red but must yield to oncoming traffic; except if the sign says "NO TURN ON RED", you cannotb) After stopping, you may turn left from a one-way street onto a one-way street ; except if the sign says "NO TURN ON RED", you cannot

6. If the signal for your lane is a red arrow pointing up, you may not go straight

7. If the signal for your lane is a green arrow pointing left or right, you may turn in the direction of the arrow, after yielding the right-of-way to vehicles within the intersection, even if the red light is burning at the same time

8. If the signal for your lane is a green arrow pointing up, you may go straight, after yielding the right-of-way to vehicles within the intersection, even if the red light is burning at the same time

9. If the signal for your lane is a yellow arrow, it means the same thing as the yellow ball, but applies only to movement in the direction of the arrow

10. If the signal is a blinking red ball, come to a complete stop and then enter the intersection, except you must yield to other vehicles already in the intersection

11. If the signal is a blinking yellow ball, enter the intersection with caution, except you must yield to other vehicles already in the intersection

12. If none of the bulbs on the signal head are illuminated (power outage), come to a complete stop and then enter the intersection with caution, except you must yield to other vehicles already in the intersection

*special thanks to Ken Sides

A motorist has to make a lot of decisions

Roundabouts are simple.

before driving through a traffic signal...even when they aren’t fatigued or distracted.

If the general public trusts us

[deadly] status quo?

to design safe infrastructure, can wemake progress by following the

Transportation engineers now havea much broader perspective about

the purpose and use of streets.

Complete street

Tactical urbanismWalk to school

Arts district

Crosswalks

Bus shelters

Traffic calming

Livable streetEconomic development

Bike to schoolLess parking

Separated bike paths

Road diet

Placemaking

We have the engineering knowledge base.

We have a strong roundabout policy.

So how do we buildmore roundabouts in Virginia?

2.Process + ToolsPart

VirginiaChris Tiesler

Statewide Roundabout Guidance

Background

State agencies with successful roundabout programs generally have Policy statement Process

Internally apply the intent of the policy Tools

Assist in performing assessments

VDOT has a strong policy, but has lacked a process and tools to consistently implement and adhere to its policy

Three Tools

Screening Guidance Planning-level feasibility

Spreadsheet Tool Compare control forms Go beyond operations Easy to use/maintain User Manual companion

Design Guidance Principle-based Resource

Tool #1: Planning-Level Screening Document

Determine General Lane Needs

Figure 1 – Planning Level Daily Intersection Volumes (NCHRP Report 672 Exhibit 3-12)

0

5,000

10,000

15,000

20,000

25,000

30,000

35,000

40,000

45,000

50,000

0% 10% 20% 30% 40%

Left-Turn Percentage

AAD

T

Double-lane roundabout likely to operate acceptably

Single-lane roundabout may be sufficient (additional analysis needed)

Single-lane roundabout likely to operate acceptably

Double-lane roundabout may be sufficient (additional analysis needed)

Planning Level Daily Intersection Volumes (NCHRP Report 672 Exhibit 3-12)

Planning-Level Screening

Right of Way Determine approximate footprint

Figure 1 – Planning Level Daily Intersection Volumes (NCHRP Report 672 Exhibit 3-12)

Adapted from NCHRP Report 672 (Exhibit 6-9)

Roundabout C onfiguration Typical Design

Vehicle C ommon Inscribed C ircle

Diameter Range*

Mini-Roundabout SU-30

45 to 90 ft

Single-Lane Roundabout B-40 90 to 150 ft WB-50 105 to 150 ft WB-67

130 to 180 ft

Multilane Roundabout (2 lanes) WB-50 150 to 220 ft WB-67

165 to 220 ft

Multilane Roundabout (3 lanes) WB-50 200 to 250 ft WB-67

220 to 300 ft

* Assumes 90-degree angles between entries and no more than four legs. List of possible design vehicles not all-inclusive.

Planning-Level Screening

Approximate magnitude/size of roundabout and associated impacts can be initially judged

Consider: Right of way Environmental

impacts Utilities Topography

Figure 1 – Planning Level Daily Intersection Volumes (NCHRP Report 672 Exhibit 3-12)

140’ ICD

Planning-Level Screening

Network Interactions Consider site and surround intersection(s) in close proximity

Intersection spacing?Adjacent traffic control – related queuing characteristicsCorridor considerations

Roundabouts particularly desirable when: Low percentage of through trips and high percentage of turns Safety improvements desirable Community enhancement/aesthetics Traffic calming High number of U-turns Unusual geometry creates design and signal phasing challenges

Figure 1 – Planning Level Daily Intersection Volumes (NCHRP Report 672 Exhibit 3-12)

Tool #2: Spreadsheet Tool

Compares life-cycle costs of roundabout to traffic signal or stop-control across range of criteria

Elements included: Safety Vehicular delay Operations and Maintenance Capital design and construction costs Right-of-way cost

Elements not included: Emissions and fuel consumption Other qualitative elements

Key Takeaways

Easy to use

Requires basic information that is readily available

Evaluate criteria beyond traffic operations

BETTER DECISIONS

What do I need?

Opening year and design year ADTsRecent turning movement countsOperational analysis to determine: Turn lane requirements Control delay Basic geometric layout

Historical crash data (optional)Preliminary cost estimate

User is prompted for additional detail as needed (case-by-case) Assumptions can be made Straightforward inputs

Introduction Tab

Provides spreadsheet navigation instructions

Color Coding Orange cells indicate required

data entry Blue cells indicate optional

data entry Red text provides further

instruction

MainENTRY Tab

User-friendly drop list fields allow for easy scenario selection

Non-applicable fields blocked out in gray

Highway Safety Manual Content

Part C – Predictive Method 10: Two-Lane Rural Highways 11: Multilane Rural Highways 12: Urban and Suburban Arterials

Part D – Crash Modification Factors 13: Roadway Segments 14: Intersections 15: Interchanges 16: Special Facilities 17: Networks

Glossary

Part A – Introduction and Fundamentals 1: Introduction 2: Human Factors 3: Fundamentals

Part B – Roadway Safety Management 4: Network Screening 5: Diagnosis 6: Select Countermeasures 7: Economic Evaluation 8: Prioritization 9: Safety Effectiveness Evaluation

AdjustSPF Tab

Data entered uses HSM Part C CMFs to complete the SPF calculations

Only fields for selected facility type are shown

DelayENTRY Tab

VDOT Spreadsheet Tool - Results

Calculates the monetary safety and delay benefit of the roundabout Compares to ops/maintenance and initial capital costs expenditures

Life Cycle Benefit/Cost Ratio

Spreadsheet Tool Summary

Spreadsheet tool compares intersection control forms across wide range of criteria Operations Safety Costs

Construction Operations/Maintenance (Life Cycle)

Easy to use and maintain

Supplements initial roundabout screening tool

User Manual provides detailed information regarding methodologies

Tool #3: Design Guidance Document

Condensed design guidance for practitionersEmphasize key principles Planning

Economic Evaluation Public Involvement

Operations Safety Design

Design Vehicle Splitter Islands Truck Apron Non-motorized Users Curbs/Drainage Traffic Control Devices Illumination Landscaping

Next Steps

Roll out tentatively planned for July 2014 to coincide with update to VDOT Road Design Manual

All three tools likely to be housed and available on VDOT’s external Roundabouts website http://www.virginiadot.org/info/faq-roundabouts.asp

Education & training for VDOT staff and consultant community

Andy @Boenau@timmonsgroup

Chris @ctiesler@kittelson

TRB 4th International Conference on Roundabouts April 17, 2014

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