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John N. LaPlante, P.E., P.T.O.E. T.Y. Lin International
Prepared for the:Annual Meeting of the AASHTO
Highways Subcommittee on Design
July 15, 2008
Complete Streets: Basic Design Considerations
What is a Complete Street?
A Complete Street is safe, comfortable and convenient for
travel via automobile, foot, bicycle, and transit.
An incomplete street:
Too narrow for comfortable 'sharing'
An incomplete street:
Uninviting for transit riders
An incomplete street:
Room for vehicles, but no room for people
We know how to build right
• AASHTO Ped Guide published in October 2004.
• Included many new and innovative concepts.
• Reiterated some often overlooked AASHTO Green Book guidelines.
AASHTO Ped Guide
AASHTO Green Book encourages roadway designers to provide for peds. “Interactions of pedestrians with traffic are a major consideration in highway planning and design.”
Current Green Book
Safety is a key consideration. Peds are the most vulnerable of all roadway users.
AASHTO Ped Guide
Accessibility is also key. Ped facilities should accommodate peds of all abilities.
AASHTO Ped Guide
Basic Design Elements
• Sidewalks• Crossing the street • Medians and islands• Traffic signals• Crosswalks• Crosswalk markings• Curb extensions• Transit• Bicycles
Sidewalks
Not after space for future sidewalks is all gone
AASHTO Ped GuideSidewalk Design
Sidewalk Design
“All roadways along which pedestrians are not prohibited should include an area where occasional pedestrians can safely walk.”
– Unpaved walkway– Shoulders in rural areas– Sidewalks in urban areas
Locations with no sidewalks are twice as likely to have vehicle-pedestrian crashes than sites with sidewalks.
AASHTO Ped Guide
Pedestrians can get by without sidewalks on Pedestrians can get by without sidewalks on quiet streetsquiet streets
Ashland OR
Shoulders serve pedestrians in rural areasShoulders serve pedestrians in rural areas
Benton County OR
At a certain point, sidewalks are neededAt a certain point, sidewalks are needed
Canyonville OR
““Goat trail” indicates sidewalks are neededGoat trail” indicates sidewalks are needed
Jefferson Parish
Set triggers for future sidewalks• Development densities
• Developer requirements
• Going from open to closed drainage
AASHTO Ped GuideSidewalk Design
The AASHTO “Green Book” states:
“Sidewalks are integral parts of city streets”
Sidewalks are not added to streets, Sidewalks are not added to streets, they are they are part of the streetpart of the street
Fredericksburg VA
Forcing pedestrian Forcing pedestrian into streetinto street
Sidewalks should Sidewalks should not end midblocknot end midblock
Sidewalk DesignSidewalks on only one side of the street?
– Weakens pedestrian safety by requiring unnecessary street crossings
– Lacks connectivity– Generally not recommended
AASHTO Ped Guide
Mountable curbs are not appropriate on local streetsMountable curbs are not appropriate on local streets
Casper WY
Separated sidewalk is uncluttered,Separated sidewalk is uncluttered, pleasant pleasant to walk onto walk on
Reno NV
Parkway separation makes it easy to meet Parkway separation makes it easy to meet ADA at drivewaysADA at driveways
Salem OR
Narrow curbside sidewalks are inadequate in Narrow curbside sidewalks are inadequate in commercial areas commercial areas
Reno NV
Crossing the Street
Pedestrians shouldn’t be terrified crossing the streetPedestrians shouldn’t be terrified crossing the street
Santa Ana CA
Pedestrians want & need to cross the street safely
High speeds lead to greater chance of serious injury & death
Speed Matters
Child dart-out: speed is a factor!
150’
First scenario: Speed 25 MPH
100’
100’ = distance covered in 2.5 sec. perception/reaction time
150’
Driver applies brakes
First scenario: Speed 25 MPHDriver applies
brakes
100’
150’
50’ stopping distance (wet pavement)
50’
First scenario: Speed 25 MPH
Result: Nothing happens beyond one scared child, driver & parent!
100’
150’
50’
Second scenario: Speed 38MPH
140’
140’ = distance covered in 2.5 sec. perception/reaction time
150’
Driver applies brakes
Second scenario: Speed 38MPH
140’
150’
Driver applies brakes
Second scenario: Speed 38MPH
140’
150’
In the last 10’ car slows to 36 MPH
Second scenario: Speed 38MPH
150’
Result: a high speed crash
Where do these two scenarios lie on the pedestrian fatality risk scale?
Second scenario: Crash speed 36 MPH
First scenario: no crash
Complete Streets Design Controls
• Complete Streets design begins with
Target Speed:– Desirable operating speed– Mobility for motor vehicles – Safety for pedestrians and bicyclists– Usually posted speed limit
Conventional design Conventional design criteria primarily based criteria primarily based on:on:
Functional classFunctional class
Design SpeedDesign Speed
Defining Mobility
• Typical experience:– 45 mph speed– 2 min wait at signal
Defining Mobility
• Viable alternative:– 2-way progression set for 30 mph
Benefit/Cost Analysis
• Reducing speed from 45 mph to 30 mph– For a 5-mile trip, a 3.33-minute delay– Assume 30,000 ADT and $20/hr driver cost– $12.154 million in loss to economy, right?
• Wrong!– Delay for each person is still 3.33 minutes– Less time than their daily stop for Starbucks
• Community benefit– Slower operating speeds– Safer and more comfortable ped crossings
Roadway Capacity Analysis• Design urban roadways to LOS D
• Designing to LOS C for peak hour means:– Unnecessary pavement, waste of tax dollars– Increased ped crossing times, thus reducing
vehicular movement times– Increased operating speeds for other 22 hours
Medians and IslandsReduce crashes by 40%
Basic Principle Break long complex crossing into two simpler crossings
Corvallis OR
Poor sign placementPoor sign placement
Choosing location for island: must have O & D
Corvallis OR
In this case, apartments across from bus stop and stores
Place cut-through at an angle…
Flush median is not much of a refugeFlush median is not much of a refuge
Crystal City VA
Flush median is not much of a refugeFlush median is not much of a refuge
Atlanta GA
Replace with a raised islandReplace with a raised island
Atlanta GA
Intersection Design
Small, tight intersections best for pedestrians…Simple, few conflicts, slow speeds
Intersection Design – Curb Radii
– Actual curb radius (R1)
– Effective radius (R2)
AASHTO Ped Guide
Keeping it tight: Curb radii
* Impossible move on one-way street
Intersection geometry:
Large radius increases crossing distance, and affects crosswalk & ramp placement
Effect of large radius on crosswalk
Additional area to crossAdditional area to cross+ Higher speed turns+ Higher speed turns
It’s more than the distance…
Effect of large radius on crosswalk
Hard to figure out where to crossHard to figure out where to cross
Effect of large radius on driversEffect of large radius on drivers
They drive fast…They drive fast…
… … ignoring pedestriansignoring pedestrians
Intersection Design – Curb Radii
AASHTO Ped Guide
• Use entire available width to turn into
• Select appropriate design vehicle
Must consider design vehicles, but don’t choose Must consider design vehicles, but don’t choose larger vehicle than necessarylarger vehicle than necessary
We shouldn’t design for the exceptional vehicleWe shouldn’t design for the exceptional vehicle
Raised islands at intersection separate conflicts
Right-Turn Slip Lane: Design for pedestrians
High speed, head turner low visibility of pedestrians
Wide Angle
Old Way
2020O
O
55 to 60 degree angle between vehicle flows
New proposal
Slower vehicle speeds, good visibility of pedestrians
Tighter angle
20O
20O
Island with fairly good geometry
Free Flow Turn Lanes
Prevent pedestrian movements
Free Flow Turn Lanes
Prevent pedestrian movements
Expressway Ramps
• Right angle intersection where ramp meets cross street
• Design urban exits for 20 mph
Free Flow Turn Lanes
Signal timing & other simple Signal timing & other simple innovative ideas to minimize innovative ideas to minimize
pedestrian delay & conflictspedestrian delay & conflicts
Traffic Signals
Use short signal cycle lengthUse short signal cycle length
Long wait Long wait causes stacking: peds wait in street,auses stacking: peds wait in street,or don’t wait and cross against the signalor don’t wait and cross against the signal
Portland OR
Set pedestrian signal to recall to “Walk”
when major street is set to recall to green
Peds should not be required to push a button
1.1. WALKWALK
2.2. Flashing DON’T WALK *Flashing DON’T WALK *
3.3. Steady DON’T WALKSteady DON’T WALK
1/2 of Americans don’t understand 1/2 of Americans don’t understand it;it;
Is there a better system?Is there a better system?
Current system:Current system:
* Flashing red hand/don’t * Flashing red hand/don’t walk is ped clearance walk is ped clearance intervalinterval
Very counterintuitiveVery counterintuitive
Problem with current system:Problem with current system:Pedestrians not sure if they can start during Pedestrians not sure if they can start during
flashing don’t walkflashing don’t walkBoston MA
Corvallis OR
Problem with current system:Problem with current system:Pedestrians not sure if they can start during Pedestrians not sure if they can start during
flashing don’t walkflashing don’t walk
Pedestrian count-down signal tells pedestrians Pedestrian count-down signal tells pedestrians how much crossing time is left …how much crossing time is left …
Springfield OR
Reno NV
Pedestrian count-down signal tells pedestrians Pedestrian count-down signal tells pedestrians how much crossing time is left …how much crossing time is left …
Results from San Francisco:Results from San Francisco:
25% Crash Reduction Factor after 25% Crash Reduction Factor after countdown signals installedcountdown signals installed
Countdown Clocks
• The existing option of using pedestrian countdown displays will now be a requirement for all new ped installations
• All existing pedestrian signal installations should be upgraded with countdown clocks within 10 years
• Only exception is where the duration of the pedestrian change interval (flashing Don’t Walk) is less than 7 seconds
Countdown Clocks in MUTCD
• Old MUTCD recommends using a pedestrian walking speed of 4.0 fps, and at crossings with older or disabled pedestrians, use 3.0 fps
Pedestrian signal timing
• However, recent studies found that 4.0 fps based on average walking speeds (not 15th percentile)
• New NCUTCD will use 3.5 fps for FDW and 3.0 fps for overall WALK phase
Crosswalks
Basic crosswalk question:
Do crosswalks increase safety, or do they Do crosswalks increase safety, or do they encourage pedestrians to cross without looking?encourage pedestrians to cross without looking?
(“(“false sense of securityfalse sense of security”)”)
Safety Effects of Marked vs Unmarked Crosswalks at Uncontrolled Locations: Executive
Summary and Recommended Guidelines
U.S. Department of TransportationFederal Highway AdministrationResearch and DevelopmentTurner-Fairbank Highway Research Center6300 Georgetown PikeMcLean, VA 22101-2296
byUNC Highway
Safety Research Center
March 2002
1. OK to mark crosswalks at ADT <10,000 w/o median
2. OK to mark crosswalks at ADT <15,000 w median
3. Medians reduce crash risk significantly
4. Marked crosswalk alone not recommended on high ADT roadways
5. Signalization or other treatments should be considered where large portion of pedestrians are young and/or elderly
Conclusions/recommendations
Many locations are suitable for a marked crosswalk
Suitable location for a marked crosswalk:Two-lane, ADT <10,000, high use, driver expectancy
Madison WI
Suitable location for a marked crosswalk:Two-lane, slow speed, high use, driver expectancy
Washington DC
Crosswalk MarkingsCrosswalk Markings
Once the decision has been made Once the decision has been made to mark a crosswalk,to mark a crosswalk,
the crosswalk must be visible to the crosswalk must be visible to thethe
DRIVERDRIVER
What the pedestrian sees
What the driver sees
Visible Crosswalks
Crosswalk Marking Types
Crosswalk Visibility
Crosswalk Visibility
Longitudinal markings are more visible to Longitudinal markings are more visible to driver at a distancedriver at a distance
What the pedestrian sees
What the driver sees
Continental Markings
Visible Crosswalks
Textured xwalks: in theory, more visible. Textured xwalks: in theory, more visible. Reality?Reality?
What the pedestrian seesWhat the pedestrian sees
Corvallis OR
What the driver seesWhat the driver sees
Corvallis OR
Supplement textured crosswalks with white stripes to ensure visibility
Phoenix OR
Brick Street with Brick Street with asphalt asphalt crosswalkscrosswalks
Pedestrian Pedestrian perspectiveperspective
Orlando FL
DriverDriverperspectiveperspective
Orlando FL
Curb Extensions
– Relocate obstructions
– Eliminate parking on approaches
– Curb extensions when parking remains
AASHTO Ped GuideIntersection Design – Sight Lines
and Curb Bulbs
Curb extensions
Most focus has been on reducing crossing distance
Better visibility (both ways) Traffic calming Room for street furniture Additional on-street parking *
* corner is “protected”
Other advantages
Pedestrian is waiting on curb, behind parked car
Salem OR
Curb extension places pedestrian where he can see and be seen
A new way to look at curb extensions
Not something you add to a street
Imagine the street w/o on-street parking
Now think of parking as the bonus!
Curb extension integrated with the sidewalk
Consider this your Consider this your normal curb linenormal curb line
Not thisNot this
Fredericksburg VA
Transit
Transit Objectives
Ensure transit stops are convenient and accessible
Ensure transit users can safely cross the street at every transit stop
Address transit operators concerns Address other road users needs
Transit: designing for successful intermodalismTransit: designing for successful intermodalism
Transit: bus is most common modeTransit: bus is most common mode
Madison WI
Transit: only choice for many peopleTransit: only choice for many people
Madison WI
Sidewalks should be wide enough to provide Sidewalks should be wide enough to provide space for waiting, boarding and passing.space for waiting, boarding and passing.
Widen beyond ADA minimum for wheelchair padWiden beyond ADA minimum for wheelchair pad
Narrow curbside sidewalk provides insufficient Narrow curbside sidewalk provides insufficient space for waitingspace for waiting
Honolulu HI
Narrow curbside sidewalk provides insufficient Narrow curbside sidewalk provides insufficient space for waiting especially when bus comes & space for waiting especially when bus comes &
people boardpeople boardHonolulu HI
Bus shelter placement: it should not obstruct Bus shelter placement: it should not obstruct sidewalksidewalk
Portland OR
Bus shelters must be accessible Bus shelters must be accessible (grass around (grass around it is inaccessible)it is inaccessible)
Honolulu HI
Honolulu HI
Bus shelters must be accessible Bus shelters must be accessible (grass around (grass around it is inaccessible)it is inaccessible)
Separated sidewalk allows bus shelter placement in Separated sidewalk allows bus shelter placement in planter stripplanter strip
Eugene OR
All known crossing techniques apply to transit stopsAll known crossing techniques apply to transit stops
Portland OR
Place crosswalks behind bus stop!Place crosswalks behind bus stop!
Madison WI
Why?Why?1.1. Peds can see trafficPeds can see traffic2.2. Bus driver can moveBus driver can move3.3. Bus doesn’t run over pedsBus doesn’t run over peds
Bicycles
Definition: Bike Route System
• “Bikeway” is generic term to cover any facility designated for
bicycle traffic
• Shared Roadway
Facility Selection
– Recognizes that most bicycle travel now occurs on streets and highways without bikeway designation
Facility Selection
• Signed Shared Roadway
– Signing “should indicate particular advantages to using the route over an alternative”
No point in striping local streets with bike lanes
Bike lanes most appropriate on urban thoroughfares
They get you from one part of town to another efficiently
Intersections stop or signal controlled – the “right way”
No point in striping local streets with bike lanes
Facility Selection
• Bicycle Lanes– Can reduce travel lane
RELATIVE DANGER INDEXOf various types of facilities
Major Streets w/o bike lanesMajor Streets w/o bike lanes 1.281.28 Minor Streets w/o bike lanesMinor Streets w/o bike lanes 1.04 *1.04 * Streets with bike lanesStreets with bike lanes 0.50.5 Mixed-use pathsMixed-use paths 0.670.67 SidewalksSidewalks 5.325.32(* = shared roadway)(* = shared roadway)
1.00 = median1.00 = median
Source: William Moritz, U.W. - “Accident Rates for Various Bicycle Facilities” - based on 2374 riders, 4.4 million miles
39%
25%34%
1%
Riders on sidewalk against traffic
Riders on road with traffic
Riders on road against traffic
Riders on sidewalk with traffic
Riders at sites with sidewalks & no bike lanes
Total sw riders: 64%
Bike Lanes: Effect on Rider Characteristics
Bike Lanes: Effect on Rider Characteristics
13%
11%
73%3%
Riders on sidewalk against traffic
Riders on road with traffic
Riders on road against traffic
Riders on sw with traffic
Riders at sites with sidewalks & bike lanes
Total sw riders: 24%
QUESTIONS?
COMMENTS?
CONCERNS?