Effective Speed Management Measures: Methodology and ...docs.trb.org/prp/14-4188.pdf · 1 Effective Speed Management Measures: Methodology and ... a self-enforcement solution while

Effective Speed Management Measures: Methodology and 1

Application in City of Edmonton 2

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Hossam Abdelgawad, P.Eng., Ph.D. 1,2

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Project Engineer, Transportation Engineering 6

Email: [email protected] 7

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Jaime Garcia, P.Eng., PTP, Ph.D. 1 10

Project Manager, Transportation Engineering 11


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Alireza Hadayeghi, P.Eng., Ph.D. 1 15

Director, Transportation 16


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Ken Karunaratne M.Eng., P.Eng, PTOE 3 20

Senior Traffic Engineer, Transportation Operations 21


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1 CIMA+, 3027 Harvester Road, Suite 400, Burlington, Ontario L7N 3G7, CANADA 27

2 Cairo University, Faculty of Engineering, 12631, Giza, Egypt 28

3 City of Edmonton, 16th Floor, Century Place, 9803 - 102A Avenue NW, Edmonton Alberta T5J 3A3 29

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Paper submitted for presentation at the 93rd

Annual Meeting of the Transportation Research Board, and 32 publication in Transportation Research Record: Journal of the Transportation Research Board 33

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Submission Date: August 1st, 2013 36

Abstract: 248 words, Body: 5199, Figure + Tables: 9, Total: 7697 37

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TRB 2014 Annual Meeting Paper revised from original submittal.

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Abdelgawad H, Garcia J., Hadayeghi A., and Karunaratne K.

ABSTRACT 1

Every year, staff and members of Council of communities of all sizes along Canada receive numerous 2

complaints from residents regarding vehicles speeding along residential roads. Although traffic volumes 3

on these types of streets can be considered minor, traffic speeds detected in such types of road are causing 4

a concern. Aside of law enforcement, the most common response to these complains is the 5

implementation of traffic calming since this type of engineering measure has the potential not only to 6

lessen the direct negative impact of road traffic, but to promote the integration of urban environments in 7

which all modes of transportation can be adequately integrated as part of the roadway network. However, 8

many of these attempts have shown questionable effectiveness in reducing travelling speed “corridor-9

wide” with a perceived effect limited to the area surrounding a traffic calming device. Through a 10

comprehensive literature search and jurisdiction scan approach; this paper investigates the effectiveness 11

of speed management measures while considering the following factors: 1) self-enforcement measures; 2) 12

corridor-wide effect; 3) before and after study findings; and 4) potential impacts on transit routes, 13

emergency vehicle response time, snow removal activities and pedestrian/cyclists. The results of this 14

investigation are summarized in a selection matrix format for the most effective speed management 15

measures. A methodology for applying these measures on collector roads is introduced by considering the 16

context-sensitive characteristics of the study area and the speed management selection matrix. This 17

methodology is then applied to two case studies on the City of Edmonton roads. 18


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INTRODUCTION 1

Rationale for Speed Management vs. Traffic Calming 2 What is referred to as traffic calming and speed management in previous studies often has many 3

synonyms in different countries, cities, and jurisdictions. For example, In San Jose, CA, it is called 4

“neighbourhood traffic management”; in Boulder, CO, it is “traffic mitigation”; in Sarasota, Fl, it is 5

traffic abatement, and another common name is “neighborhood traffic control”, ITE/FHWA (1). In many 6

North American (NA) and European cities, the most common names are “traffic calming” and “speed 7

management” (2). In this respect, the subcommittee on Traffic Calming of the Institute of Transportation 8

Engineers (ITE) defined traffic calming as “the combination of mainly physically measures that reduce 9

the negative effects of motor vehicle use, alter driver behaviour and improve conditions for non-10

motorized street users” (3). 11

Since traffic calming measures as defined by the ITE subcommittee rely on the laws of physics rather 12

than the human psychology to slow down traffic, it is reasonable to assume that traffic calming refers 13

primarily to measures that affect travel speeds. Traffic management, on the other hand, attempts to control 14

the volume of traffic through the use of regulatory devices such as turn prohibitions or one-way streets. 15

Although these naming conventions may refer to different measures and implementation strategies, these 16

names are used interchangeably in the literature and in practice. 17

Typical traffic calming measures aim to reduce speed as well as other combinations of volume and 18

collisions. Speed management, on the other hand, goes beyond the localized traffic calming initiatives by 19

managing speeds in a “corridor-wide” environment by deploying physical measures, visual treatments 20

and changing drivers’ habits and enforcement (2). This approach is known as self-explaining roads 21

(SERs) or self-enforcing roads (SERs) which primarily uses road design elements to evoke correct and 22

expected driving behaviour from road users (4). Speed management is now extended to a variety of 23

measures applied to all types of roads, including collector roads and highway as well as urban arterial 24

roads, to cope more safely with increasing flow and speeding traffic. 25

In the context of this paper, we focus on speed management techniques that have the potential to reduce 26

speeds while harnessing some traffic calming measures that focus on speed reduction and control. While 27

speed management measures aim at reducing speeding and collisions they could also negatively affect the 28

operation of transit vehicle, response time of emergency vehicles, and sometime pedestrians and cyclists; 29

an issue that we discuss in the paper. 30

Research Motivation and Objectives 31 Speed management measures have been widely implemented worldwide at different capacities with some 32

successful implementations (mainly reported based on before-and-after studies) but also with some 33

questionable effectiveness of some of these measures. Identifying effective and proven speed 34

management measures adds a number of questions. First, what is the experience of jurisdictions/cities 35

with the measure? Second, what is the effectiveness of the measure when applied along a corridor? 36

Moreover, does the measure introduce a self-enforcement solution while considering the perception of 37

drivers? What are the side effects of implementing the measure? and finally, after identifying effective 38

speed management measures, how these measures could be implemented given the context-sensitive 39

nature of each speeding problem including: roadway features and characteristics, magnitude of reported 40

speed violation, existence of transit service, emergency routes, on-street parking, to name a few. 41

With these questions in mind, the objectives of this research are structured as follows: 42

Conduct a literature search to document the experience of jurisdictions/cities when applying short 43

term or long term speed management measures; 44

Evaluate the significance of speed management measures and identify the most effective reported 45

measures in a selection matrix format; 46

Identify the side effects of implementing speed management measures; 47


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Develop a methodology for implementing speed management measures by considering the 1

context-sensitive characteristics of the study area and the speed management selection matrix; 2

Implement the speed management methodology on a Case Study. 3

This research constitutes a comprehensive review and evaluation of effective speed management 4

measures, while applying the results of this evaluation on a case study on the City of Edmonton roads. In 5

this research the authors do not attempt to conduct a before and after study as this has to be contemplated 6

by the City of Edmonton which was not ready at the time of this research. 7

COMPREHENSIVE EVALUATION OF SPEED MANAGEMENT MEASURES 8

Literature Search and Jurisdiction Scan Approach 9 A number of Canadian municipalities, US cities, and OECD countries with significant traffic calming 10

experience formed the list for literature search on traffic calming and/or speed management policies. In 11

addition, the most common cities cited in the “ITE Canadian Guide to Neighborhood Traffic Calming” 12

were considered (3). Findings from design manuals, guidelines and reports were also used to complement 13

the experience of different cities/jurisdictions with speed management measures (5- 8) 14

Our approach in conducting the literature search and jurisdiction scan focused on evaluating both traffic 15

calming and speed management measures with proven effectiveness for speed reduction using the 16

following criteria: 17

Example Installation: cities that have implemented the measure; 18

Applicability and Locations to Avoid: applicable (or avoidable) locations and streets; 19

Potential Advantages: speed reduction, volume reduction, conflict reduction, environment; 20

Potential Disadvantages: emergency response, maintenance and winter, significant disadvantages; 21

Jurisdiction Experience and Recommendations; and 22

Literature Review Search: guidelines, manuals, scientific papers. 23

Effectiveness of Traffic Calming Measures 24 The summary shown in Table 1 builds on the findings of the jurisdiction scan and literature search while 25

focusing on measures that shows at least 3kph reported speed reductions. 26

TABLE 1 Summary of Significant Speed Reduction Measures 27

Measure Studies show potential to reduce speed (in kilometres per

hour) or percentage of reduction

Raised Crosswalk 6 to 12 kph

Rumble Strip 3 to 8 kph

Speed hump 6 to 25 kph

Speed Tables around 11 kph and by up to 60% in countries like China

Speed Cushions (Lumps) 10% speed reduction

Chicane 6 to15 kph and by 26% in some cities

Curb extension/ neckdown/ chokers 1.5 to 8 kph and by 26% in some cities

Raised median island 3 to 8 kph

Traffic circle (sometimes referred to as

mini-roundabouts)

6 to 14 kph

Roadway Narrowing (lane narrowing) 1.5 to 10 kph and by 21% in some cities in England

Road Diet 5 to 12 kph and by 12%-32% in New Zealand and Vancouver


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Effectiveness of Speed Management Measures 1 Despite the large number of studies concerning speed management and traffic calming measures, very 2

few reports include results of a systematic evaluation methodology to quantify the effectiveness of such 3

measures. In addition, the majority of studies focused solely on before-and-after analysis without 4

considering other dimensions such as: time of analysis (e.g., off peak vs peak periods), season of analysis 5

(e.g., winter vs summer), location of analysis (spot location, along a corridor, area-wide), active modes of 6

transportation (pedestrians and bicyclists), spatial variation of measures (e.g., influence zone vs 7

spontaneous effect) (9-12). 8 9

It is therefore essential to assess the system wide impacts of these measures if applied individually or in 10

combination with other measures. Therefore in this paper close attention was given to review studies that 11

reported reduction in speed using systematic evaluation perspectives, including the following factors: 1) 12

self-enforcement, 2) corridor-wide effect, 3) before and after study findings, and 4) potential impacts. 13

Self-Enforcement 14

In accordance with Lockwood (13) the self-enforcement aspect of traffic calming focused on “altering 15

driver behavior” in order to lower speeds, reduce aggressive driving and increase respect for non-16

motorized users of the streets. 17

The most common method to achieve a self-enforcement speed management environment is to locate a 18

series of speed management measures in a sequence that adapts the driver behaviour by generating a 19

smooth “slow-and-go” speed profile as shown in FIGURE 1-a. 20

In this respect, the most common source of midpoint speeds identified in the literature search is based on 21

the ITE/FHWA “Traffic Calming – State of Practice”, the findings of which indicate that (1): 22

Measures such as 22-foot tables and longer tables (raised crosswalks and speed tables), circles 23

(traffic circles), and narrowings (curb extension/neckdown/chokers, sidewalk extension and raised 24

median island) have a proven effect on speed reductions after implementation, and 25

A series of those measures adequately located along a corridor will create a self-enforcement 26

environment in which the observed 85th percentile speed between measures may be reduced by a 27

range of 4 - 18 %. 28

Corridor-Wide Effect 29

It should be noted that speed reduction obtained after implementation of a series of measures along a 30

corridor depends on: the current prevailing speed, its relation to the desired speed, and the type and 31

location of the selected measures. 32

Although guidelines and standards of practice such as in (1,3) do not provide explicit details about the 33

expected speed reductions of these types of combined treatments; more recent research discussed the use 34

of 85th percentile speed at midpoints, speed profiles, zone of influence and variation in speed to estimate 35

the scheme-wide effects of traffic calming (14-18). (see FIGURE 1-b). 36

In addition the distance between measures will directly affect the effectiveness of the selected measures. 37

If a longer spacing between measures is provided, higher midpoint speeds will be observed (16). Based on 38

the physical relationship between those elements, it is possible to estimate maximum spacing of speed 39

management measures in order to maintain a “desirable speed” between measures and create a “corridor-40

wide” speed management effect. 41

42


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1

FIGURE 1 Zone of Influence and Speed Differential of Multiple Measures for Self-Enforced Roadways. 2

After considering the approaches/equations for determining the required spacing of speed management 3

measures, it is possible to assume that: 4

If the 85th percentile speed of the collector before implementation is available, the equation provided 5

by the City of Anaheim to calculate 85th percentile speed at midpoint after implementation is the 6

most comprehensive (15); 7

The location of speed management measures such as raised crosswalks, speed tables and traffic 8

circles can be estimated in order to maintain a “desirable speed” between measures and to create a 9

“corridor-wide” speed management effect; and 10

Physical characteristics of these types of measures (speed differential, acceleration/ deceleration 11

ratios and separation between measures) can be estimated to maintain a sustained speed reduction. 12

Before and After Study Effect 13

To further investigate the effectiveness of the speed management measures summarized in TABLE 1, an 14

additional review was dedicated to before-and-after study effects by using the following approach: 15

Only before and after studies for a series of measures along a corridor with documented before/after 16

dates were reviewed. It should be noted that this requirement drastically narrowed the search space 17

since most before-and-after studies are focused on the effect of a single measure. 18

Due to the approach followed by these studies, if a combination of measures was used along the 19

corridor, the results after implementation cannot be pinpointed to a specific type of measure. 20

The most recent status of the measures was identified using Google maps search. 21

The results of this review are summarized in TABLE 2. 22

(a) Self-enforced traffic calming measures (17)

(b) Speed Profiling and zone of influence(16)


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TABLE 2 Evaluation of Before and After Studies for Key Speed Management Measures 1

Location Before & After Dates and Applied

Measure

Effect and Status

State Route

116, Amherst

(19)

Before: December, 2004

After: October 2005

Measure: (4) Central Narrowing

Islands and curb extensions

Data collected at 3 different locations along the State

Route 116 corridor (0.33 mile), with two lanes of traffic

and parking.

Status: Still in place (September 2009)

Frome Road,

North

Vancouver

(20)

Before: April 2008

After: February 2009

Measure: Curb extensions (bulges) and

road narrowing

The 85th

percentile speed decreased 4% (from 56 km/h

to 54 km/h)

Status: Still on trial stage (May 2009)

Goyder Street,

Canberra (21)

Before: 2002

After: 2006

Measure: Wombat (raised) Crossings

and Raised Platform

The 85th

percentile speed decreased from 65 km/h to 58

km/h.

Status: Still in place (December 2009)

Kihapai Street,

Honolulu (22)

Before: 2002

After: 2003

Measure: Chicane (1), Bulbouts (6),

Median (3), Speed Tables (4)

Speed reductions between 3 to 9 mph were observed.

The variations may be due to differences in the type of

devices installed at each location.

Status: Chicane was removed in 2004 due to public

complains.

Montanoso

Drive, Mission

Viejo (23)

Before: 2005

After: 2007 – 2008

Measure: (8) Curb extensions and (3)

Partial Raised Median Islands

Montanoso Drive is a 40-foot wide undivided collector

street, posted speed of 30 mph. The 85th

percentile speed

prior to implementation ranged from 34 to 38 mph.

Status: Still in Place (September 2011)

Central

Lonsdale

West, North

Vancouver

(24)

Before: 2006

After: Spring-Fall 2009

Area-wide implementation consisting

of Speed Humps, Speed Tables, Raised

Crosswalks, Traffic Circles, Curb

Extensions, and Crosswalks with

Flashing Lights.

Traffic speeds decreased by more than 10% in at least

one direction in all the 23 tested locations. Although an

average speed reduction in traffic speeds of 18% was

observed on Mahon Avenue (Traffic Circles location),

the City received significant complaints regarding their

final implementation.

Status: Still in trial phase (May 2009)

College

Terrace, Palo

Alto

California

(25)

Before: May 2005 – May 2006

After: May - October 2007

Area wide implementation of Traffic

Circles and Speed Tables

A decrease of overall 85th

percentile speeds in the

neighborhood of 10%. The City received a petition

signed by several residents challenging the effectiveness

of traffic circles and requesting their removal.

Status: Still in place (March 2011)

West River

Road,

Cambridge

(26)

Before: 2009

After: 2010

Traffic Circle, Speed Cushions and

Pavement Markings

A decrease in vehicle speeds on West River Road of 3 to

8 km per hour.

Status: In 2012, the geometric design of the traffic circle

was modified to provide access to emergency vehicles.

City of

Portland

(27,28)

Before: 1987 -1988 -1989

After: 1991

City-Wide analysis of Traffic Circles

Performance

The main focus of this analysis was the determination of

change in the distribution of vehicles speed

Status: Traffic Calming Measures Installed Between

1996 to 2006

2

3

Based on the review of the before-and-after studies presented above, the following findings can be 4

offered: 5

A combination of road narrowing measures (i.e. curb extensions and raised median islands) can 6

decrease the observed 85th percentile speed between 1 and 7 miles/hour 7

A combination of traffic circles with curb extensions can decrease the observed 85th percentile speed 8

between 10% and 18 %; 9


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A combination of vertical deflection (i.e. raised crosswalks and speed tables) and road narrowing 1

measures (curb extensions) can decrease the 85th percentile speed by approximately 10% ; and 2

Effectiveness of short term measures such as line striping are inconsistent and vary from no effect to 3

1 to 7 miles/hour (similar to other road narrowing measures). 4

Impacts on Fire and Emergency Services 5

The ultimate goal of speed management measures devices is to improve pedestrian safety and promote 6

livable communities without compromising response times of emergency vehicles. Achieving effective 7

service levels at an emergency scene directly relates to minimizing response times of emergency 8

personnel. Several published studies have found that a single traffic calming device can delay EMS and 9

Fire vehicle responses by 2 to 10 seconds, depending on the measure and the emergency vehicle response 10

type. In addition, vertical deflection measures have been found to cause injuries to responding emergency 11

personnel (neck, back and head), exacerbate injuries and comfort of a patient being transported to the 12

hospital As a result, multiple speed management measures along a corridor can cumulatively cause 13

significant delays and can have negative consequences in the emergency outcome (29,30). 14

Impacts on Transit Services 15

Due to their dimensions, transit buses are affected by horizontal and vertical deflections. Due to 16

consideration for the comfort and convenience of passengers, as well as the repetitiveness of the bus 17

schedule, horizontal deflection devices are generally preferred over vertical deflections in locations 18

considered as transit routes. However, it should be noted that horizontal measures alone may not always 19

be effective at reducing speeds to the required level. 20

Therefore, to maximize the benefits of a speed management scheme and to minimize the effects on transit 21

services, several sources (31-33) suggested taking into consideration the following factors: 22

The proposed speed management scheme (number of measures and location) should avoid a 23

substantial increase in travel time; 24

A recommended operational speed of 25 kph or less when crossing traffic calming measures; 25

The proposed speed management scheme should not include more than five (5) vertical deflection 26

measures per transit route; and 27

The flat surface of speed tables and raised crosswalks should be a minimum of 6 metres long. 28

Impacts on Snow Maintenance 29

Although very few studies reported a quantitative impact of speed management strategies on snow 30

removal activities, it is expected that reducing speed would have an impact on snow removal and 31

response times. Therefore, measures should be clearly identified and equipment operators made aware of 32

these types of measures. This will improve the snow removal operation and help prevent damage to the 33

snow removal equipment or the measure itself. In some cases the snow and ice removal equipment are at 34

capacity. In such cases the current fleet of snow removal might not cope with any additional delays - 35

imposed by speed management treatments - in response to major winter events. 36

Impacts on Pedestrians and Cyclists 37

Physical measures (either horizontal or vertical) could address the issue of speeding on roadways but 38

could easily jeopardize the accessibility and safety of pedestrians and bicyclists. Therefore, design 39

standards for physical treatments should accommodate the minimum requirements for bicyclists and 40

pedestrians. In some cases, there is a contradiction between the introduced speed management measure 41

and bicyclists and/or pedestrians. The following discussion highlights important considerations of a few 42

measures for illustration purposes and is not meant to comprehend all speed management measures (34): 43


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Vertical speed management measures are not conducive to bicycle travel in general; therefore, they 1

should be used carefully, especially for heavy travelled bicycle routes; 2

Horizontal measures should be clearly marked to enable bicyclists to identify and anticipate them. 3

To reduce the risk of bicyclists’ being squeezed, horizontal measures should generally be used in 4

conjunction with other speed control devices such as speed tables at the narrowing; 5

Medians and refuge islands are most valuable on major corridors that present safety problems for 6

bicyclists and pedestrians wishing to cross. A minimum central refuge width should be maintained 7

for safe use by those with wheelchairs, bicycles, baby strollers, etc.; and 8

Road narrowing and road diets are among the few speed management measures that have the 9

potential to control speed, while at the same time creating enough room for bicyclists. 10

11

As discussed above, finding the balance between improving the level of safety for pedestrians/cyclists in a 12

livable community and maintaining timely snow removal and emergency response services is not 13

insurmountable. It is therefore important to involve all the stakeholders and the public to understand the 14

benefits of implementing speed management strategies and the potential impact on snow removal 15

services. 16

After considering the results summarized in TABLE 1, the potential of speed management measures in 17

creating a self-enforcement solution along a corridor (i.e., not a single measure/point), the findings from 18

before-and-after studies; and the potential impact on transit/emergency/snow removal services; the 19

following key speed management measures can be recommended for implementation as part of a 20

corridor-wide speed management plan: 21

1. Raised Crosswalk 22

2. Speed Tables 23

3. Curb Extension/Neckdown/Chokers 24

4. Raised Median Islands 25

5. Traffic Circles 26

METHODOLOGY FOR THE IMPLEMENTATION OF KEY SPEED MANAGEMENT 27

MEASURES 28

Concept of Context-Zones 29 The use of the “Context Zone” concept as a way to define the specific characteristics of an urban area was 30

initially presented by Andres Duany in 2001, as part of the Smart Code alternative to zoning (35). 31

In this concept, a “transect” or cross-section similar to the one depicted in FIGURE 2-a, is used to identify 32

the type of urban environments that compose a community from the downtown core to the rural areas 33

surrounding the community. This concept was later integrated into the ITE recommended practice as a 34

tool for “designing urban streets that are compatible with and supportive of the surrounding context and 35

community” (36). 36

ITE suggested the use of four context zones (suburban, general urban, urban center and urban core) to 37

describe how context varies around a community. Following this approach to urban characterization, the 38

geographic location and specific characteristics of the roadway network can be directly related to each 39

type of Context Zone as shown in FIGURE 2-b. 40


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1

FIGURE 2 Context Zone Concept. 2

Development of Selection Matrix 3 TABLE 1 forms a comprehensive list of all potential speed management measures. However, for the 4

development of a selection matrix - that maps the roadway characteristics to the recommended speed 5

management measures- the five (5) key speed management measures described above were evaluated 6

against the roadway characteristics to include only the speed management measures that are applicable to 7

the type of collector roads present within the different context zones. The evaluation criteria shown in 8

TABLE 3 considered the following factors: 9

Anticipated speed/speed limit for which the speed management measure is warranted 10

Recommended volume for different types of roads 11

Land use purpose and the surrounding area of the studied corridor 12

Cross section and right-of-way recommendations 13

Availability of parking and the effect of the speed management measure on parking 14

Availability of pedestrian infrastructure (e.g., sidewalk) and its effect on the choice of the speed 15

management measure 16

Availability of a bike lane and its effect on the choice of the speed management measure 17

Availability of a transit route and its effect on the choice of the speed management measure 18

19

(a)

Through traffic is served by the entire roadway

network

A more linear roadway pattern provides with better

visualization of the road ahead (sight distance)

Majority of intersections provides for full

movements of traffic

Driveways may have direct access to collector

roads.

Local streets are designed for low traffic

volumes and minimal through traffic

Collectors are designed to reduce vehicular

speed through the use of curvilinear patterns

and discontinuities

Preference for T rather than four-leg

intersections

Limited or restrict access from driveways

(b)


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TABLE 3 Speed Management Measures – Selection Matrix 1

Measure Raised

Crosswalk

Speed Tables Curb

Extension/

Neckdown/

Chokers

Raised Median

Island

Traffic Circle

Mean Operating

Speed (at the

measure)

25 -35 km/h 25 - 35 km/h 35 - 45 km/h 35 - 45 km/h V =

5

85th

percentile

speed at

midpoint after

the measure

47 km/h 47 km/h 50 km/h 50 km/h 47 km/h

Traffic volumes

(vehicles per

day)

1,500 to 5,000 1,500 to 5,000 1,500 to

10,000

> 10,000 1,500 to 10,000 vpd.

Cross Section

(ROW)

Not recommended

in Limited ROW

and preferred for

local collectors

Recommended

for minor

collector and

local roads

All roadways May require

additional ROW

for narrow

sections.

Require specific

ROW and adequate

space for large

vehicles manoeuvres

Pedestrian

infrastructure

(sidewalk)

There must be at

least one sidewalk

Could be used

as raised

sidewalk at the

crossings

Improve

pedestrian

safety

Can be used as

refuge island in

wide crossings

Not recommended

with area with high

pedestrian volumes

Availability of

Parking

- - Requires the

removal of

on-street

parking

May require the

removal of

some on-street

parking

May require the

removal of on-street

parking

Bike Route No effect on

bicycles at

moderate speed

Minor impact

on bike lanes

Potential

impact on

cyclists

Potential impact

on cyclists

Potential impact on

cyclists

Transit or

Emergency

Service Route

Only be

considered if

desired speed

cannot be

accomplished by

other measures.

Only be

considered if

desired speed

cannot be

accomplished

by other

measures 6.

Should allow

space for

large vehicles

to pass.

Should be

located at bus

stops.

No effect on

transit and

emergency

vehicles if

adequate

clearance is

provided.

Should not be used

on transit routes or

emergency service

routes unless

designed as

mountable.

5 Where: V= 95

th percentile speed (km/h) of through vehicles in the traffic circle, R = radius of the centreline of the

vehicle’s path (m) at that point, S = sight distance correction factor, (1.0 for good and 0.00 for poor sight distance)

(9).

2

Implementation of the Selection Matrix 3 In order to implement any measures form the selection matrix, a number of steps has to performed first as 4

explained below. A graphic representation of these steps is presented in FIGURE 3. 5

Identify the local characteristics of the selected collector road: The context zone and the 6

roadway configuration can provide an insight about the type of neighbourhood, land use and 7

urban characteristics present along the selected collector. 8

Identify Infrastructure Availability: Specific information about the selected roadway such as: 9

location and extend of parking and/or bicycle lanes, signalized intersections and the use of 10

portions or the full length of the selected collector as transit and/or emergency service route will 11

narrow the locations in which a speed management measures can or cannot be implemented. 12


12


Confirm if the selected collect is considered part of a transit and/or emergency service 1 route: Due to the limitations imposed by Transit and Fire Department, any proposed speed 2

management measures must limit the negative effects of horizontal and vertical deflections. 3

Use the Selection Matrix to select the most suitable short or long term speed management 4 measure for each location along the selected corridor: Relate the local characteristics of the 5

selected collector road with the road characteristics presented on the Selection Matrix to identify 6

which type of speed management measures can be implemented along the selected collector 7

taking into consideration the implementation time (short or long term). 8

9

FIGURE 3 Graphical Representation of the Selection Matrix Implementation. 10

APPLICATION ON CITY OF EDMONTON COLLECTOR ROADS 11

Selection of Corridors and Site Characteristics 12 To demonstrate the use of the selection matrix summarized in TABLE 3, two representative collectors 13

were selected in the City of Edmonton: 9th Avenue (From 119 St NW to 111 St NW) and 122 Avenue 14

(From 107 St NW to Fort Rd). The methodology for implementing the selected speed management 15

measures shown in FIGURE 3 is applied in this section to recommend the speed management measures 16

along the two corridors. In preparation to implement the selection matrix defined above, TABLE 4 17

summarizes the main corridor characteristics and the context zone analysis for 9th Avenue and 122 18

Avenue. 19


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TABLE 4 Corridor Characteristics and Context Zone Analysis 1

Implementation

Steps

Corridor

9th

Avenue

122 Avenue

Local

Characteristics

Length: 1.6 km, Cross-Section: 4 lanes,

Width: 13 m, Access Points: 20 local streets

and Cul-de sac areas; all of them have yield

signs, with average 105 m distance between

access points. Control: Only one signalized

intersection and one stop control sign.

Infrastructure and services: Transit route

with 12 bus stops, no bike lanes, no emergency

service route, snow route.

Speed and Traffic Volume: speed limit is 50

kph, spot speed studies indicate that 60-80% of

drivers exceeded the posted speed limit and

that the 85th

percentile speed was around 73

kph, AADT≈ 1800.

Length: 3 km; Cross-Section: 4 lanes; Width:

13 m; Access Points: 28 access points with

average of 112 m between access points;

Control: 2 signalized intersections, 26 stop

controlled.

Infrastructure and services: two transit

routes, no bike lanes, no emergency service

route, snow route, on-street parking.

Speed and Traffic Volume: speed limit is 50

kph, 2 spot speed studies indicate that drivers

exceeded the posted speed limit by around 10

kph, , AADT_first location ≈ 1800,

AADT_second location ≈ 2300.

Context Zone

Analysis

- Most of the areas along the two corridors have transit stops and snow route signs which form a

challenge to the introduction of any measure that reduces the existing pavement width.

- Traffic circles are candidate measures at many locations; however, their location is somehow

pre-determined at 4-leg or T intersections.

- Few location-specific measures can be

identified at the intersection of 9th

Ave and

9a Ave, and 113 St; therefore, the remaining

measures along the corridor are expected to

be corridor-wide measures.

- The intersection of 9th

Ave and 111 St NW is

a signalized intersection with wide lanes and

wide area of crossing. However, 111 St is a

major arterial that shouldn’t be interrupted

by any vertical deflection measure.

- Few location-specific measures can be

identified near the intersection with 107 St,

103 St, 97 St, 95a St, 89 St, 82 St, and Ford

Rd. The remaining measures along the

corridor are expected to be corridor-wide

measures.

- There are a few designated pedestrian

crossing locations at the intersection with

103 St, 95a St, 89 St.

- There are a few locations that show

pedestrian and school crossing areas.

Recommended Corridor-Wide Speed Management Scheme 2 Given the local characteristics and the context zone analysis summarized in TABLE 4, the next step is to 3

determine the appropriate spacing between measures to maintain a prevailing speed along the corridor 4

while considering the zone of influence of each measure. Since the 85th percentile speed is a common 5

result of speed studies conducted by the City of Edmonton, the City of Anaheim (15) formula defining the 6

relationship between the speed reduction and separation between measures was used in this paper: 7

85th

midpoint(mph) = 85th

slow point(mph) + (85th

street(mph) – 85th

slow point(mph)) * 0.56 * (1 – e-0.004*spacing(feet)

)

where 85th

midpoint(mph), 85th

slow point(mph) , 85th street(mph) are the resulting 85

th percentile speed at midpoint after

implementation, at the measure, and before implementation, respectively.

The 85th

midpoint(mph) value depends on the specific measure as shown in TABLE 3, resulting in the 8

following midpoint speeds: 9

- Raised Crosswalk , Speed Table , Traffic Circle = 47 kph = 29.2 mph 10 - Curb Extension/Neckdown/Chokers, Raised Median= 50 kph / 1.609 = 31 mph 11

9th Avenue 122 Avenue


14


The 85th

slow point(mph) value also depends on the specific measure as shown in TABLE 3, resulting in the 1

following slow point speeds: 2

- Raised Crosswalk = 30 kph = 19 mph - Speed Table = 30 kph = 19 mph 3 - Curb Extension / Neckdown / Chokers = 40 kph = 24 mph - Raised Median = 40 kph = 24 mph 4 - Traffic Circle = 30 kph = 19 mph 5

9th Avenue Most Suitable Corridor-Wide Speed Management Scheme 6

The 85th percentile speed along 9

th Avenue was recorded at 73 kph (above speed limit by 23 kph). This 7

indicates a serious speeding problem along the residential area. 8

85th

street(mph) = 73 kph / 1.609 = 45 mph 9

10

By applying the City of Anaheim equation the minimum spacing between measures is defined below: 11 - Raised Crosswalk Spacing = 95 m - Speed Table = 95 m 12 - Curb Extension / Neckdown / Chokers = 70 m - Raised Median = 70 m 13 - Traffic Circle = 95 m 14

From a practical point of view, the City of Edmonton foresees a range of spacing between 100m and 15

150m to be reasonable as it results in a midpoint speed range of 48 kph – 51 kph for Raised Crosswalk, 16

Speed Table, and Traffic Circle; and a range of 52–55 kph for Curb Extension and Raised Median. 17

By considering 1) the local characteristics of 9th Ave, 2) the available infrastructure, and 3) the calculated 18

spacing between measures, the recommended measures are shown in FIGURE 4 that summarizes the 19

speed management measures on a map with the distances between the measures. 20

21

FIGURE 4 Identification and Location of Speed Management Measures along 9th

Avenue. 22

Characteristics

Measures

Traffic Circle

Split Speed Table

Raised Median

Curb Extension/Neckdown/Chokers

Legend


15


122 Avenue Most Suitable Corridor-Wide Speed Management Scheme 1

The 85th percentile speed along 122 Avenue was recorded at 63 kph (above speed limit by 13 kph). 2

85th

street(mph) = 63 kph / 1.609 = 39 mph 3

4

By applying the City of Anaheim equation the minimum spacing between measures is defined below: 5 - Raised Crosswalk = 180 m - Speed Table = 180 m 6 - Curb Extension / Neckdown / Chokers = 140 m - Raised Median = 140 m 7 - Traffic Circle = 180 m 8

The spacing calculated above is to maintain a speed of 47 kph for Raised Crosswalk, Speed Table, and 9

Traffic Circle, and a speed of 50 kph for raised median and curb extension. As discussed above, the 10

average distance between intersections along 122 Ave is around 112 m, which implies – if following the 11

above calculated spacing- the implementation of one measure at each intersection resulting in 27 12

measures along the 3 km corridor. If the spacing between measures is around 111 m, this will result in 13

85th midpoint (mph) of 44 kph which is somewhat lower than the speed limit (50 kph). Therefore, we 14

recommend allowing an 85th midpoint (mph) of 48 kph for the raised crosswalk, speed table, and traffic 15

circles, which will result in a spacing of 250 m for each of these measures. 16

By considering 1) the local characteristics of 122 Ave, 2) the available infrastructure, and 3) the 17

calculated spacing between measures, the recommended measures are shown in FIGURE 5 that 18

summarizes the speed management measures on a map with the distances between the measures. 19

20

FIGURE 5 Identification and Location of Speed Management Measures along 122 Avenue. 21

Characteristics

Measures

Traffic Circle

Raised Crosswalk

Raised Median

Curb Extension/Neckdown/Chokers

Legend


16


It is worth noting that the location of traffic circles has to comply with the existing corridor alignment and 1

roadway intersections; and has to be mountable to facilitate the manoeuver of large vehicles. Also the 2

City has expressed a concern on the implementation of corridor-wide vertical deflection measures; 3

therefore their implementation is kept to a minimum to minimize the impact on Fire and Transit services. 4

SUMMARY AND CONCLUSIONS 5

A comprehensive literature review of technical papers, manuals, guidelines and reports related to the 6

selection, implementation and effects of speed management measures suggested that although several 7

devices currently in use on North America can affect the observed speed along a specific corridor; in most 8

cases their effect is not long-standing and localized only in the immediate vicinity of the device. 9

Furthermore, the process followed for the selection of these of devices does not consider the cumulative 10

effect of several devices at the “corridor-level”. 11

The results of our review suggested that the selection of a series of traffic calming devices based on 12

factors such as 1) self-enforcement, 2) corridor-wide effect, 3) before and after study findings, and 4) 13

potential impacts, can support the design of a methodology for the implementation of a corridor-wide 14

speed management strategy. This methodology included the development of a selection matrix for the 15

most effective speed management measures and presented its applicability to selected corridors according 16

to the context-zone characteristics of these corridors. 17

The usefulness of the proposed methodology under practical conditions was tested using two 18

representative collector roads in the City of Edmonton: 9th Avenue (From 119 St NW to 111 St NW) and 19

122 Avenue (From 107 St NW to Fort Rd). Data on the local characteristics and available infrastructure 20

on the two corridors were collected to assist in the selection matrix and context-zone analysis; and a set of 21

speed management measures were distributed along the collector roads to maintain the 85th percentile 22

speed along the collectors under the corridor-wide preferred posted speed. 23

The results of this practical study indicate that the proposed methodology can be easily followed and 24

implemented by practitioners using information that is commonly available. It is expected that in this 25

particular test case, the City of Edmonton may contemplate the implementation of the recommended 26

speed management measures. 27


17


REFERENCES 1

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