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Road Diets: The Seattle Experience
Pro Walk / Pro Bike: Pro Place
September 11, 2012
Brian Dougherty
Carol McMahan
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Where is Seattle?
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Complete Streets
• 16% of households do not have a car
• Seniors
• Youth
• Safety
• Transit riders
Ultimately, we all need
complete streets
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Seattle’s Complete Streets Approach
• Vision: Streets that are
safe, convenient and
accessible for everyone
• Plans: Bicycle, Pedestrian,
Transit, Freight
• Funding: Bridging the Gap,
• Implementation: Complete
Streets checklist
• Outreach: Community
collaboration
• Opportunities: Redesigning
city streets• Funding: Bridging the Gap,
state, federal grantscity streets
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For whom road diets might apply
• ADT < 15,000
• ADT 15,000 - 20,000
• ADT >20,000
OK
Evaluate
Maybe• ADT >20,000
Towns Small CitiesSuburbsLarge Cities
Maybe
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Why Road Diets?
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Complete Streets Approach
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Economic Benefits
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Economic Benefits
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Why Road Diets? Fewer Collisions
US Federal Highway Administration Proven Safety
Measure to reduce all collisions by 29%
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Why Road Diets? Pedestrian Safety
A modest decrease in motor vehicle speed can dramatically increase survival in pedestrian crashes
Speed reduction from 40 to 30 increases survival rate by 5 x
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Seattle Road Diet History
6
8
10
12
14
Miles
0
2
4
6
1972 -1978
1979 -1985
1986 -1992
1993 -1999
2000 -2006
2007 -2012
Miles
Projects
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Seattle Road Diet History
• 34 road diets have been
installed in Seattle since
1972
• 1972 – 2006: 21 Projects
• 2007 – 2012: 13 Projects• 2007 – 2012: 13 Projects
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How are Corridors Identified?
• Complete Streets for
capital projects
• Bicycle Master Plan
• Pedestrian Master Plan
• Community requests for
neighborhood plan
implementation S Columbian Way
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What Factors are Considered?
Tier 1: Traffic Operations
Nickerson StBefore After
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What Factors are Considered?
Tier 2: Safety/Collisions
N 130th St (2010)Before After
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What Factors are Considered?
Tier 3: Livability
7th Ave (2010)Before After
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Don’t Forget the Design Details
•Freight•Lane width•Turning movements
•Transit•Lane width•Lane width•Turning movements•Stop consolidation•Trolley lines
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Don’t Forget the Design Details
• Parking– Peak hour
– Utilization
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Don’t Forget the Design Details
• Pedestrian crossings– Refuge islands
– Marked crosswalks
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Don’t Forget the Design Details
• Signals
– Detection
– Optimize corridor
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Don’t Forget the Design Details
• Pavement Condition
Spot repair
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Out Reach: Common Concerns• There will be gridlock!
– Maintain capacity at signalized intersections
– Gain efficiency by removing left turns from travel lanes
• People will cut though the neighborhood!
– Monitor pre and post project implementation
– Implement traffic calming measures if problems occur– Implement traffic calming measures if problems occur
• I’ll be trapped in my driveway by all the traffic!
– Sight distance is improved for left turns
– Access from side streets and driveways improved by
crossing only one travel lane to the two-way left turn lane.
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Out Reach: Common Concerns
Street Before Comments
After Comments
Requests to remove
NE 125th St 394 7 3
Nickerson St 66 8 0
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Pitfalls
Carolina Beach, North Carolina
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Before & After StudiesData needs Before Study After Study (>1 year)
ADT √ √
Bike and Ped Counts √ √
Crash Data √ √
Speed √ √
Transit Operations √ √
Turning vehicle counts √ √Turning vehicle counts √ √
Gap Studies √ √
Parking use √ √
Side street diversion √ √
Vehicle Classification √ √
Resident Satisfaction √ √
Business Satisfaction √ √
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Case Study: Stone Way N
• 1.2 miles
• ADT – 13,000
• Burke-Gilman Trail Access
• Woodland Park Access
• Within 5 blocks – 8 schools, 2 • Within 5 blocks – 8 schools, 2
libraries and 5 parks
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Stone Way N: Marked Crosswalks
• Uncontrolled, marked
crosswalks at 4
intersections.
• Crosswalk guidelines
changed in 2004.changed in 2004.
• Marked crosswalks would
be non-compliant with
four-lane cross section.
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Stone Way N: Bicycle Master Plan
• Adopted in 2007.
• Stone one of the first
projects completed under
the plan.the plan.
• Recommended climbing
lane and sharrow.
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Stone Way N: 85th Percentile Speed
• Speed limit 30
• 85th percentile was 37
mph prior to
rechannelization
• Dropped to 36 mph
northbound
• Dropped to 34 mph
soundbound
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Stone Way N: Aggressive Speeders
• 3% of vehicles traveled at
40 mph+ prior to
rechannelization
• Fewer than 1% traveled
at 40mph+ after
rechannelization
• Reducing the number of • Reducing the number of
top speeders greatly
reduces seriousness of
collisions and injuries.
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Stone Way N: Bicycle Volume
• Increased 35%
• Represents almost 15%
of the peak hour traffic
volume!volume!
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Stone Way N: Motor Vehicle Volume
• ADT Dropped 6%
(consistent with citywide
trend between 2006-08)
• Peak Hour volume
dropped approximately
5%5%
• Off-peak volume actually
increased south of 45th
Street
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Stone Way N: Neighborhood Traffic
• Four non-arterial streets
commonly mentioned as
alternatives to Stone
• Volume decreased on all
four of those streets
• Traffic did not divert after • Traffic did not divert after
rechannelization.
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Stone Way N: Collisions
• Total collisions declined
14%
• Injury collisions declined
33%
• Angle collisions declined
56%
• Bicycle collisions no
change, but rate declined
• Pedestrian collisions
declined 80%
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Stone Way N: Conclusions
• Speed has declined
• Collisions have declined
• Pedestrian crossings are
safer
• Bicycle volume has
increasedincreased
• Traffic has not diverted to
neighborhood streets
• Peak hour capacity has
been maintained
• Strong case for
implementing road diets
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Possible Elements of Future Studies
Study Data:
• Pre and Post survey
of nearby businesses
and residents
• Traffic signal LOS
To Address/Answer:
• Livability
• Impact to business
• Travel time
• Diversions to other • Traffic signal LOS
• Volume of parallel
arterials
• Diversions to other
arterial streets
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Follow-up studies and monitoring
• Volume of principal street
/peak hour capacity
• Speed and collisions
• Traffic signal level of service• Traffic signal level of service
• Volume of parallel arterials
• Travel time
• Bicycle volumes
Stone Way
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NE 125th St Factors:
• ADT 16,200
• 4 lanes to 2 lanes
with TWLTL and bike
lanes
• Business district
• High bus usage• High bus usage
• High number of
pedestrian collisions
Before
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NE 125th Street
Before After
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NE 125th St
Volume
ADT
4%
AM
6%
Speed
PM
12%
Speed
85th%
-8%
TOP
END
-69%
OVER
30
-12%
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Nickerson St:
Before After
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Nickerson Case Study
Before
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Nickerson Case Study
After
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Columbian Way Complete Street
• ADT 11,200
• Repave project
• 4 lanes to 2 lanes
with TWLTL and bike with TWLTL and bike
lanes
• New sidewalks
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Recent Results
Street ADT
begin
ADT
change
Collisions 85th % Top end
speeders
Travel
time
Stone Way 13,000 -6% - 14% - 6% - 80% N/A
NE 125th St 16,200 + 4% N/A - 8% - 69%+ 1.5
min
Nickerson St 18,600 - 1% - 23% - 21% - 94% N/A
Columbian
Way11,200 + 20% No change - 6% -50% N/A
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Not the end of the story: Dexter Ave N
Before After
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Not the end of the story: Dexter Ave N
Before After
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Just Completed: S Othello Street
Before After
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Additional Resources
• Nickerson Street Before and After Study– http://www.seattle.gov/transportation/nickerson.htm
• Stone Way Before and After Study– http://www.seattle.gov/transportation/docs/StoneWaybeforeafterFINAL.pdf
• FHWA: Proven Safety Countermeasures• FHWA: Proven Safety Countermeasures– http://safety.fhwa.dot.gov/provencountermeasures/index.htm
• NACTO Guides– http://nacto.org/
• National Complete Streets Coalition– http://www.completestreets.org/
•