1. Road Diets Jennifer A. Rosales, P.E. Presentation to ACEC/ODOT
Senior Professional Associate
Supervising Transportation Engineer
Presentation to ACEC/ODOT
April 15, 2008

2. Overview What is a “Road Diet” Road Diet Handbook Case Studies
Feasibility Factors
Design Guidelines

3. Road Diet Concept Lane Reduction Four-to-two lane conversion
Benefits to all modes of transportation
Improved mobility and access
Improved livability and quality of life
Economic and community goals
Four-to-three lane conversion
Two-lane roadway with a two-way left turn lane
In cities throughout the world, four-lane undivided roadways have been converted to three lane roadways which provide benefits to all modes of transportation including transit riders, bicyclists, pedestrians, motorists and trucks.
Photo simulation by Todd Boulanger, COV

4. Road Diet Concept Safety benefits Reduced vehicle speeds
Reduced conflict points
Improved sight distance
- Improved pedestrian & bike safety
Recent case studies for converting four lanes of roadway to a two-lane roadway with a two-way left turn lane, referred to as “road diets,” show reduced vehicle speeds and reduced collisions and injuries.
Road diet benefits for pedestrians and transit users include improved and safer crossing of the street since the number of through traffic lanes to cross the street is reduced from four lanes to two lanes. In addition, road diets have been shown to reduce speeds, which make pedestrian crossings easier.
After the road diet conversion, there is improvement in comfort level and safety for all modes of transportation traveling along the street. Vehicles have a buffer with the addition (re-striping) of a bike lane or on-street parking which moves vehicles further from fixed objects such as utility poles, fire hydrants, and other objects.
Graphics by PB

5. Road Diet Concept Minimal effect on capacity ADT thresholds
Traffic diversion 2-15 percent
After the road diet conversion, there is improvement in comfort level and safety for all modes of transportation traveling along the street. Vehicles have a buffer with the addition (re-striping) of a bike lane or on-street parking which moves vehicles further from fixed objects such as utility poles, fire hydrants, and other objects.
The road diet has been shown to increase uniform traffic flow and reduce collisions from turning movement conflicts.
With the addition of bike lanes, bicyclists have a dedicated bike lane and no longer have to travel in a mixed-use vehicle lane. Pedestrians also gain more separation from motorists with the bike lane or on-street parking as a buffer.
It has been shown that road diets have minimal effect on vehicle capacity by moving the left turn movements out of the through traffic into the center turn lane.
In a four-lane undivided roadway, the left through lane of the roadway is often used as the left-turn lane. As traffic volumes increase, these left-turn vehicles find it increasingly more difficult to make the left turn and thus cause considerable delay to the through movements. Moving left-turn movements out of the main traffic flow to the center-turn lane, results in less vehicle friction and reduces rear-end type collisions as well. However, implementing road diets on roadways with an average daily traffic over 20,000 vehicles per day can result in increased traffic congestion that may lead to traffic diversion to alternate facilities. Road diet studies have shown traffic diversion ranging from 2 to 15 percent, which has not been reported as a problem in most jurisdictions.
On four-lane undivided roadways, drivers change lanes to pass slower moving vehicles and to pass vehicles stopped in the left through lane waiting for a traffic gap to make a left turn. This adds friction, vehicle conflicts, and reduces roadway performance. In addition, drivers can use the left turn lane as a passing lane and drive faster with a spare lane in their travel direction. On two-lane roadways, vehicle speeds are limited by the leading vehicle.
Photo by James Hencke, PB

6. Road Diet Concept Simple as re-striping Cost-effective
Optional enhancements
Enhances environment
Road diet projects can be designed and constructed by simply re-striping the roadway and re-using the existing pavement width and curbs.
The addition of landscaped medians, improvements to pedestrian crossings and facilities, street trees and curbside planters, and improved transit user facilities such as bus shelters are optional for an enhanced road diet project.
Cost effective – financially feasible
Improves the community and Enhances the social and built environment
Photo by GB Arrington, PB
Photo by James Hencke, PB

7. Road Diet Concept Other Road Diet Examples One-way streets
Three to two lanes
Six to five lanes

8. Road Diet Handbook: Setting Trends by Livable Streets
PB’s commitment to Sustainability
Road Diet Handbook: Setting Trends by Livable Streets
Foreword
Acknowledgments
1.0 Introduction
2.0 Previous Studies
3.0 Case Studies
4.0 Road Diet Guidelines
Appendices
References
Handbook includes:
Past studies and research
Guidelines for identifying and evaluating road diets
Design concepts and examples
Benefits of road diets
Published Fall 2005
The first of its kind, the handbook will be comprehensive and intended to become a practitioner’s guide for decision-making on the applicability of road diets.
This recommended practice handbook for road diets will provide information on the effects of road diets including the operational and safety benefits as well as the non-safety benefits including livability from the public opinion survey and data collection.
The handbook will include:
Past case studies and research
Guidelines for identifying and evaluating potential road diet candidate sites
Design concepts and examples of road diet conversions
Benefits of road diets including non-safety benefits.
Design Concepts
Typical design criteria and guidelines
Typical cross-sections
Implementation
Role of public involvement
Graphic Courtesy of PB

9. Road Diet Case Studies Vancouver, Washington Toronto, Canada
Clear Lake, Iowa
Athens, Georgia
Toronto, Canada
Dunedin, New Zealand
The case studies represent a wide range of project contexts from an urban street in Toronto, Canada to a rural street in Iowa with varying project lengths, designs, and magnitude. The local agencies for the case studies were contacted for participation, and provided data for the project.
Graphic Courtesy of PB

10. Livability Survey Purpose – examine livability impacts
Survey modeled from Livable Streets
Street perceptions including traffic, safety, comfort
Street life activities
Reactions
Survey medium varied
Each case study was surveyed using the methods described in this section. The purpose of the survey was to examine the livability impacts due to the geometric changes of streets converted by the road diet. A public opinion survey was developed and administered along four-lane undivided and converted three-lane streets. The survey was modeled from surveys conducted in Livable Streets (2) to solicit information from people living and working adjacent to the streets with factors directly related to its livability. The survey questions explored household/business characteristics, street perceptions including traffic, safety and friendliness of street, street life activities, recommended improvements, and reactions to the road diet. The surveys evaluated the livability impacts of road diet projects, addressing such issues as comfort and safety for pedestrians, bicycles, and transit users; increased landscaping and beautification opportunities; and improved quality of life and street character. Depending on the case study location and surroundings, the survey medium varied for each case study. The surveys were conducted using door-to-door survey techniques or a web survey tool.
Photo by GB Arrington, PB

11. Road Diet Case Studies Fourth Plain Boulevard in Vancouver, Washington
Arterial ~ 17,000 ADT
Re-striping project in 2002
Bike lanes
ADA ramps & utilities
Improved safety, mobility and access for all users
Before
In the City of Vancouver, Washington, a section of Fourth Plain Boulevard was recently put on a road diet by re-striping the four-lane undivided roadway to a two-lane roadway with a two-way center left turn lane and adding bicycle lanes. The “before” road diet photos of Fourth Plain Boulevard are shown below. As seen from the photos, heavy truck traffic and bicycles were forced to share the roadway. Some bicyclists were observed using the sidewalks prior to the road diet project.
The road diet photos of Fourth Plain Boulevard “after” are shown below. As seen from the photos, the bike lane adds a buffer to pedestrians walking on Fourth Plain Boulevard and to vehicles entering traffic onto Fourth Plain Boulevard. After the road diet project, bicyclists use the bike lane, and pedestrian activity has increased on Fourth Plain Boulevard. The traffic along the road diet section of Fourth Plain Boulevard after the road diet project does not experience severe congestion and operates adequately.
Fourth Plain Boulevard is designated as a principle arterial in Vancouver, Washington. Fourth Plain Boulevard serves a variety of transportation users including truck traffic through west Vancouver. Fourth Plain connects Interstate 5 to West Vancouver neighborhoods, recreation, and industry including the Port of Vancouver.
The land use adjacent to Fourth Plain Boulevard is primarily residential and commercial with residential homes fronting Fourth Plain Boulevard on the west end. Businesses, churches and merchants in the area rely on Fourth Plain Boulevard for circulation as well as access to I-5.
The average daily traffic along Fourth Plain Boulevard is about 17,000 vehicles per day with approximately 1,300 vehicles per hour during the peak hour. The posted speed on Fourth Plain Boulevard is 30 miles per hour.
After
Photo credits: Todd Boulanger, COV

12. Road Diet Case Studies Fourth Plain Boulevard in Vancouver, Washington
Crashes %
Traffic speeds %
No traffic diversion
Pedestrian & bike benefits
Redevelopment and renovations
Measured economic growth
Easier to cross street
Street “feels” safer
67% Yes, 21% Maybe, 12% No
Before
On Fourth Plain Boulevard, Vancouver, Washington, the number of reported collisions along Fourth Plain Boulevard decreased by 52 percent after the road diet project was constructed. About half of the improvement in collision rates along Fourth Plain Road can be attributed to the road diet since street collision rates of similar character in the area improved during the same time period. Pedestrian safety has improved and there were no reported pedestrian collisions along Fourth Plain Boulevard after the road diet project compared to six reported pedestrian collisions for the three years prior to the road diet project (two pedestrian collisions per year). The traffic speeds along Fourth Plain Boulevard have decreased about 18 percent after the road diet project was constructed from 29.4 miles per hour to 24.2 miles per hour. After the road diet project on Fourth Plain Boulevard, the speeds of adjacent neighborhood streets were generally lower as well.
After the road diet project, there have been no significant negative impacts to the traffic operation on Fourth Plain Boulevard. For example, there have been no reports of queuing vehicles interrupting adjacent business and residential access on Fourth Plain Boulevard. Bicyclists now use the bike lane and pedestrian activity has increased. The addition of the bicycle lane has shown other operational benefits such as including space for police enforcement and a refuge area for vehicles temporarily broken down. The bicycle operational safety along the corridor has improved, and the bicycle level of service has improved significantly since the road diet project was implemented. There was no significant traffic diversion as part of the Fourth Plain Boulevard road diet project.
On Fourth Plain Boulevard, Vancouver, Washington (road diet project implemented two years from this study), the majority of survey respondents is pleased with results of road diet project and has noticed improvements to traffic, safety, and livability. Findings related to perceived safety include:
26% think that traffic speeds are slower, while 70% perceive no change
42% think that it is easier to cross the street, while 37% perceive no change
51% said the street generally feels safer, while 30% perceived no change
Regarding new home and business improvement projects, 40% of Fourth Plain Boulevard respondents have noticed “several” new home and business improvement projects, and 54% have noticed “a few” projects. The City of Vancouver reported that redevelopment and renovation work along the corridor has proceeded at a quicker pace since the completion of the project.
Retail sales analysis found that the commercial area on, adjacent and near the Fourth Plain Boulevard road diet project performed better than comparable areas in the City. This growth occurred after the implementation of the road diet project and during a recession that affected all portions of the City. When comparing gross receipts before and after the road diet project, the commercial area in the Fourth Plain project area had a positive increase of 3.1 percent compared to negative declines of -9.8 percent to -25 percent in two other comparable community commercial zones in the City.
After
Photo credits: Todd Boulanger, COV

13. Road Diet Case Studies Baxter Street in Athens, Georgia
Arterial ~ ADT 20,000
Safety Demonstration Project in 1999
Re-striping
Bike lanes
Transit corridor
Before
Baxter Street is located in Athens, Georgia which is about 70 miles east of Atlanta and the fifth largest city in the state with a population of 102,000. Athens-Clarke County, Georgia is home to the University of Georgia and has a wide range of citizens from classic southerners to university students and alumni to “townies.”
Baxter Street is classified as an arterial and connects University of Georgia on the east to a major shopping center on west. Baxter Street runs parallel to state highway (US 78) and serves variety transportation uses. The road diet project started as a safety demonstration project when the Baxter Street needed resurfacing.
The average daily traffic along Baxter Street is 18,000 to 20,000 vehicles per day with approximately 1,500 vehicles per hour during the peak hour. The posted speed on Baxter Street is 35 miles per hour. Baxter Street is a transit street with three bus routes and includes ten bus stops along the road diet section of Baxter Street.
The land use adjacent to Baxter Street is primarily commercial along Baxter Street with residential and university facilities in the immediate project area. The residential homes consist of 55 percent rentals and 45 percent owner-occupied. The community is highly educated in the project area.
The purpose of the road diet conversion project on Baxter Street was:
To reduce the crash frequency along the corridor (especially rear-end and sideswipe)
To increase travel flow by separating through vehicles from left-turning vehicles
To designate an area within the roadway for bicycle travel
To further separate vehicles from the sidewalk edge
The road diet project on Baxter Street was completed in 1999, about five years from the time of this study.
After
Photo credits: David Clark, Athens-Clarke County, GA

14. Road Diet Case Studies Baxter Street in Athens, Georgia
Overall crashes % and at unsignalized locations %
Traffic Diversion ~ 4%
Easier to cross street
Slower speeds
Home and business improvements
Perceived number of lanes and street width is "just right"
47% Yes, 33% Maybe, 20% No
Before
The reported number of crashes on Baxter Street in Athens-Clarke County, Georgia was reduced by 53 percent from the implementation of the road diet project. In addition, the reported number of crashes at unsignalized locations was reduced by 60 percent. The number of rear-end crashes were significantly reduced by 45 percent since left turning vehicles have a center turn lane to use instead of stopping in the through lane. During the same period, county-wide crashes decreased by only 0.8%.
There were no significant impacts to the traffic volumes on Baxter Street or on adjacent streets after the road diet conversion project. It is estimated that traffic diversion experienced from the project to be about 4 percent of the Baxter Street traffic to Broad Street, a parallel arterial street north of Baxter Street. The changes in traffic volume on Baxter Street are a 4 percent decrease in daily traffic volumes and a 10 percent decrease in traffic volumes during the peak hour. A portion of the decrease in traffic volumes can be attributed to season traffic fluctuations.
On Baxter Street in Athens-Clarke County, Georgia (road diet project implemented five years from this study), the survey respondents indicated that desired outcomes of the road diet project are being achieved such as slower traffic, easier to cross the street, and more pedestrians walking along Baxter Street.
The majority of the Baxter Street survey respondents (77 %) said the street width is “just right”, while the remaining respondents said the street is “narrow” or “too narrow”. Similarly, 77% said that the number of travel lanes was “just right”, with the remainder saying there are not enough lanes. In terms of overall safety, 41% said the street is “safe” or “very safe”, 35% said that the street is “comfortable”, 24% said the street is “uncomfortable” or “very unsafe”.
On Baxter Street, 40% of the survey participants have noticed “several” new home and business improvement projects and 40% have noticed “a few” projects.
The following are the most popular responses to the top changes the survey participants would like to see on Baxter Street:
Improve street maintenance (35%)
Slower speeds (35%)
New street trees and curb side planters (31%)
More police (28%)
When asked if removing travel lanes to add bike lanes and a center left turn lane has improved local traffic issues on Baxter Street, the respondents were evenly split between “yes” and “no” with a slightly higher number of “yes” responses. Forty-seven percent would recommend this type of project in other locations, 33% responded with “maybe” and 20% would not.
After
Photo credits: David Clark, Athens-Clarke County, GA

15. Road Diet Case Studies Kaikorai Valley Road in Dunedin, New Zealand
Arterial ~ 10,000 ADT
2003 conversion
4 to 2 lanes with CTL/median
Cycle lanes and landscaping
Exist Parking
Project length ~ 2.4 km (1.5 mi)
Photos from a road diet safety improvement project in Dunedin, New Zealand are shown.
This road diet project was completed during the first half of 2003 and involved reducing a section of Kaikorai Valley Road from four lanes to two lanes and adding cycle lanes to each side of the road. As seen in the photos, a landscaped median is provided along a section of the road diet.
Kaikorai Valley Road is located in Dunedin, New Zealand, an eastern coastal New Zealand City rich in history, architecture, gardens and recreational activities. The population of the City of Dunedin is estimated at 120,000, representing about 3.3 percent of the New Zealand population. It is important to note that vehicles in New Zealand drive on the left hand side of the road.
The land use adjacent to Kaikorai Valley Road is primarily commercial along the roadway with three residential areas and two schools in the immediate project area.
The road diet project on Kaikorai Valley Road was completed in 2003, about one year from the time of this study. The length of the project is 2.4 kilometers (1.5 miles).
Kaikorai Valley Road is classified as an arterial and serves as an alternate route into and out of the Dunedin central business district from the south. The alignment of the roadway is primarily straight. Kaikorai Valley Road serves variety transportation uses, and parking is provided on both sides of the road.
The average daily traffic along Kaikorai Valley Road is about 10,000 vehicles per day with approximately 1,000 vehicles per hour during the peak hour. The posted speed on Kaikorai Valley Road is 50 km/hr (30 mph) on the north end and 70 kilometers per hour (45 miles per hour) on the south end and of the project corridor.
Photo credits: Ron Minnema, Traffic Engineer, Dunedin City Council

16. Road Diet Case Studies
Kaikorai Valley Road, Dunedin, NZ

17. Road Diet Case Studies Kaikorai Valley Road in Dunedin, New Zealand
Crashes %
Pedestrians and bicyclists
No traffic diversion
Perceived # of lanes and street width "just right"
Home and business improvements
42% Yes, 31% Maybe, 27% No
No traffic volume changes, no traffic diversion impacts, adequate traffic operation, good mobility
Safety benefits were achieved from the road diet project on Kaikorai Valley Road, Dunedin, New Zealand (left hand side of the road country). The road diet project on Kaikorai Valley Road resulted in a 30 percent crash reduction from 10 crashes per year “before” the road diet project to about 7 crashes per year “after” the road diet project was implemented. The traffic speeds along Kaikorai Valley Road were reduced after the road diet project was implemented. Approximately 88 percent of the speeds “before” the road diet project exceeded 50 kilometers per hour (30 mph) compared to approximately 69 percent of the speeds “after” the road diet project exceeded 50 kilometers per hour.
The traffic volumes on Kaikorai Valley Road in Dunedin, New Zealand have not been impacted from the road diet project and remained relatively constant. In addition, the vehicle classification and percent trucks remained relatively constant as well. The traffic volumes show a small amount of growth which indicates that traffic diversion was not experienced from the road diet project on Kaikorai Valley Road.
On Kaikorai Valley Road in Dunedin, New Zealand (road diet project implemented one year from this study), the survey respondents had mixed perceptions regarding the results of the project, but recommended this project to other streets in the City. The respondents suggested that the road is under constant repair, on-going construction and increased congestion which may be attributed to their mixed perceptions.
The Kaikorai Valley Road survey participants were more inclined to think street width was “just right” or “too wide.” Similarly, 59% said that the number of travel lanes was “just right,” while 17% said there are not enough lanes.
Regarding neighborhood aesthetics, 76% of respondents say that local residents and businesses generally “keep up” their yards and landscaping.
The following improvements were chosen by survey participants for Kaikorai Valley Road:
Improve street maintenance (32%)
Slow speeds (32%)
Reduce traffic (24%)
More police (18%)
Twenty-two percent of respondents said Kaikorai Valley Road is “OK as is”. More than half of respondents on Kaikorai Valley Road perceived positive improvements, but one block away, the majority of responses were that no improvements have occurred.
The majority of respondents, 42% would recommend this type of project in other locations, 27% would not, and 31% were not sure. Since the conversion was implemented only one year ago, several livability benefits are yet to be realized.
Photo credits: Ron Minnema, Traffic Engineer, Dunedin City Council

18. Road Diet Case Studies US 18 in Clear Lake, Iowa
State Highway ~ 12,000 ADT
Re-striping project in 2003
4 to 2 lanes with TWLTL
Extra width – shoulders
Highway through town
The road diet project in Clear Lake is located on a section of US Highway 18 on the west end of Clear Lake, Iowa. Clear Lake, Iowa is in northern Iowa about 120 miles north of Des Moines and 130 miles south of Minneapolis, Minnesota. The City of Clear Lake is a small, Midwest community with a population of about 8,200 and a tourist destination for recreational activities and visits to the Buddy Holly Crash Site.
US 18 is a state highway in Iowa and the primary east-west route through the City of Clear Lake. Railroad tracks run parallel to US 18 on the south side and operated by I & M Rail Link. US 18 serves traffic traveling in, through and out of Clear Lake as well as a variety transportation uses in Clear Lake including trucks.
The average daily traffic on US 18 through Clear Lake is approximately 12,000 vehicles per day with 1,200 vehicles per hour during the peak hour. The posted speed on US 18 is 45 miles per hour. Sidewalks do not exist along US 18 in the project area.
The land use along US 18 in the project corridor is primarily commercial with residential, commercial and recreational uses in the immediate project area. US 18 provides access to a disabled care community and facility which is one of the largest employers in Clear Lake. Also, US 18 provides access to the downtown business and tourist area.
Photos by Jennifer Rosales, PB

19. Road Diet Case Studies US 18 in Clear Lake, Iowa Crashes 65 %
Aggressive speeding %
Adequate traffic operation & good mobility
Mixed perceptions - striping confusing
Livability benefits still to be realized
Travel speeds have shown to be reduced by road diet projects. For example, a recent road diet project in Clear Lake, Iowa shows a 50 percent reduction in aggressive speeding (aggressive speeding vehicles are vehicles traveling five or more miles per hour over the posted speed limit). Reductions in overall average vehicle speeds often result in less severe and fewer collisions.
Number of crashes decreased by 65 %
Aggressive speeding reduced by 52%
Vehicles over speed limit decreased by 32%
Adequate traffic operation & good mobility
More uniform traffic speeds closer to speed limit
Mixed perceptions on street, striping confusing, conversion 1 year ago and livability benefits still to be realized
Photos by Jennifer Rosales, PB

20. Road Diet Case Studies St. George Street in Toronto, Canada
Minor Arterial ~ ADT 7,500
Through University campus
Two project phases ’93 & ‘96
Cycle lanes, on-street parking, wider sidewalks, urban landscaping
Alternate paving materials
The section of St. George Street that runs through the University of Toronto campus was put on a diet in the 1990’s. The University of Toronto was founded over 175 years ago and has over 60,000 full and part-time students. St. George Street is a multi-modal street through the St. George campus of the University of Toronto. The 160 acre (65-hectare) St. George campus is located in heart of downtown Toronto, Canada. The St. George campus has over 43,000 full and part-time students and approximately 8,000 faculty and staff.
St. George Street is classified as a minor arterial road by the City of Toronto. St. George Street is a multi-modal street serving vehicles, delivery trucks, bicyclists, pedestrians and even skateboarders. An extremely high number of pedestrians use St. George Street, and continuous sidewalks on both sides of St. George Street are provided in the pedestrian zones of the street.
The average daily traffic along St. George Street is about 7,400 vehicles per day with approximately 700 vehicles per hour during the peak hour. The posted speed on St. George Street is 40 kilometers per hour (25 miles per hour).
The road diet project on St. George Street was completed in 1996, about eight years from the time of this study. The length of the road diet project is 1,040 meters (0.65 miles). The road diet project on St. George Street has been incrementally enhanced beginning in 1993 to 1996 with the most significant changes occurring in Prior to 1993, the street operated as a four lane road during peak times, and as a two lane road during non-peak times with on-street parking permitted during non-peak times. In 1993, the number of lanes on St. George Street was reduced to two lanes by permitting parking during all hours. Bicycle lanes and a narrow painted median were added to St. George Street in 1993 as part of the lane reduction project. Turn lanes were provided at key intersections.
Photos by Jennifer Rosales, PB

21. Road Diet Case Studies

22. Road Diet Case Studies St. George Street in Toronto, Canada
Crashes %
Pedestrians and bicycles
No traffic diversion
Easier to cross street
Perceived slower speeds, "feels safer,” perceived increase in pedestrians and bicyclists
81% Yes, 12% Maybe, 6% No
No traffic volume changes, no traffic diversion impacts, adequate traffic operation, good mobility
On St. George Street in Toronto, Canada (road diet project implemented eleven years from this study), the survey participants are happy with the results of the road diet project including street width and number of lanes. The survey respondents recognize the benefits that the road diet project has produced including slower speeds and improved safety.
The St. George Street survey participants desire additional aesthetic enhancements such as greenery and replacement of concrete planters, cobblestones and pavers. The top suggestions for improvements to St. George Street follow:
Improve pedestrian crossings (57%)
Reduce traffic (45%)
More street trees and curb side planters (45%)
Truck prohibitions (34%)
Slower speeds (25%)
Regarding the street width on St. George Street, 72% of the respondents said the street is “just right”. Similarly, 79% said that the number of travel lanes was “just right”, with the remainder roughly split between too few and too many lanes.
The majority of the St. George Street survey participants felt that the street was safe, very safe or comfortable (80%). The perceived effect on the number of pedestrians and bicyclists is that 72% think that the number of pedestrians and bicyclists has increased while 28% think this has not changed.
When asked if removing travel lanes to add bike lanes and a center left turn lane has improved traffic issues on St. George Street, 84% of respondents said “yes”. Eighty-one percent would recommend this type of project in other locations, and 12% were not sure.
Significant safety improvements on St. George Street, Toronto, Canada, were realized as a result of the road diet lane reduction and narrowing project. The number of collisions was estimated to be reduced by about 40 percent from the reduction of lanes on St. George Street, from about 33 collisions per year “before” the lane reduction to about 20 collisions per year “after” the lane reduction. By narrowing the pavement and lane widths on St. George Street, the number of collisions was further reduced to about 19 collisions per year for the six years following the pavement and lane width narrowing.
The road diet project on St. George Street in Toronto, Canada resulted in no noticeable change in traffic volumes. The traffic volumes along St. George Street have remained relatively consistent before and after the narrowing of the travel lanes as part of the road diet project from 7,300 vehicles per day in 1994 to about 7,400 vehicles per day in 2003.
Photos by Jennifer Rosales, PB

23. Road Diet Example – Tacoma Street, Portland
ADT 30,000
4 lanes to 2 lanes with center turn lane
On-street parking
Curb Extensions
Refuge Islands

24. Road Diet Example – Tacoma Street, Portland
Traffic Diversion – minimal
Peak hour traffic- spread
Overall Traffic
Speeding Decreased
Increased parking
Improved pedestrian environment
Before
After

25. Road Diet Handbook: Setting Trends by Livable Streets
Foreword
Acknowledgments
1.0 Introduction
2.0 Previous Studies
3.0 Case Studies
4.0 Road Diet Guidelines
Appendices
References
Handbook includes:
Past studies and research
Guidelines for identifying and evaluating road diets
Design concepts and examples
Benefits of road diets
Published Fall 2005
The first of its kind, the handbook will be comprehensive and intended to become a practitioner’s guide for decision-making on the applicability of road diets.
This recommended practice handbook for road diets will provide information on the effects of road diets including the operational and safety benefits as well as the non-safety benefits including livability from the public opinion survey and data collection.
The handbook will include:
Past case studies and research
Guidelines for identifying and evaluating potential road diet candidate sites
Design concepts and examples of road diet conversions
Benefits of road diets including non-safety benefits.
Design Concepts
Typical design criteria and guidelines
Typical cross-sections
Implementation
Role of public involvement
Graphic Courtesy of PB

26. Road Diet Guidelines – Identification and Evaluation
Feasibility Factors
Roadway Function and Environment
Overall Traffic Volume and Level of Service
Turning Volumes and Patterns
Frequent-Stop and Slow-Moving Vehicles (Agriculture, Buses, Buggies)
Reference: Knapp, Keith and K. Giese, Guidelines for the Conversion of Urban Four-Lane Undivided Roadways to Three-Lane Two-Way Left-Turn Lane Facilities Final Report, Iowa State University, April 2001.

27. Road Diet Guidelines – Identification and Evaluation
Feasibility Factors, cont.
Weaving, Speed, and Queues
Crash Types and Patterns
Pedestrian and Bicycle Activity
Right-of-Way Availability, Cost, and Acquisition Impacts
Presence of Parallel Routes
Other Contextual Considerations
Reference: Knapp, Keith and K. Giese, Guidelines for the Conversion of Urban Four-Lane Undivided Roadways to Three-Lane Two-Way Left-Turn Lane Facilities Final Report, Iowa State University, April 2001.

28. Design Guidelines and Concepts
Traveled Way
Suggested Left-Turn Treatments
Transitions
Bicycle Facilities
On-Street Parking
Pedestrian Realm
Graphic Reference: MUTCD, Federal Highway Administration, 2003.

29. Typical Road Diet Cross-Sections
Graphics Courtesy of PB

30. Traffic Calming and Roundabout Options
Pavement texturing/coloring
Curb extensions
Medians
Landscaping
Street trees
Narrow streets
On-street parking
Chicanes
Chokers
Raised crosswalks
Raised intersections
Diagonal diverters
Selective enforcement
Photo by Jennifer Rosales, PB

31. Green Street Options/Enhancements
Street Trees
Reduced Imperviousness
Permeating or Eliminating Curb and Gutter
Vegetative Filter Strips
Swales
Linear Detention Basin
Infiltration Trench
Infiltration Basin
Solar
Photos by Jennifer Rosales, PB

32. Planning Pavement reconstruction project or jurisdictional transfer
Other supporting conditions such as parallel route
Consider community requests
Tech evaluation and community involvement – keys to success
Pilot project study
With other corridor improvements
With concurrent pavement overlay projects.

33. Implementing Public Education Manage community expectations
Consider focus groups, workshops, open houses
Consider traffic calming
Consider “greening”
Include access management strategies
Address key intersection operations
Repair sidewalks and ramps
Police enforcement

34. Road Diets - Summary Meet transportation need Safety benefits
Livability Benefits
Asset to the community
Compatible with the environment
Cost-effective
“Better than Before”
Meets transportation need
Safety and mobility for pedestrians, bicyclists, transit, motorists and trucks
Asset to the community
Livability benefits and improves quality of life
Compatible with the natural, built and social environment
Cost effective – financially feasible by reusing existing pavement, fewer materials consumed, alternate materials options
Place is “Better than Before”

35. Contact Information
Jennifer A. Rosales, P.E. PB