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Complete Streets: Basic Design Considerations 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 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 • AASHTO Ped Guide published in October 2004. • Included many new and innovative concepts. • Reiterated some often overlooked AASHTO Green Book guidelines. Current Green Book AASHTO Green Book encourages roadway designers to provide for peds. “Interactions of pedestrians with traffic are a major consideration in highway planning and design.” AASHTO Ped Guide 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. Basic Design Elements • Sidewalks • Crossing the street • Medians and islands • Traffic signals • Crosswalks • Crosswalk markings • Curb extensions • Transit • Bicycles Sidewalks AASHTO Ped Guide Sidewalk Design Not after space for future sidewalks is all gone AASHTO Ped Guide 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. Pedestrians can get by without sidewalks on quiet streets Ashland OR Shoulders serve pedestrians in rural areas Benton County OR At a certain point, sidewalks are needed Canyonville OR “Goat trail” indicates sidewalks are needed Jefferson Parish AASHTO Ped Guide Sidewalk Design Set triggers for future sidewalks • Development densities • Developer requirements • Going from open to closed drainage The AASHTO “Green Book” states: “Sidewalks are integral parts of city streets” Sidewalks are not added to streets, they are part of the street Sidewalks should not end midblock Forcing pedestrian into street Fredericksburg VA AASHTO Ped Guide Sidewalk Design Sidewalks on only one side of the street? – Generally not recommended – Lacks connectivity – Weakens pedestrian safety by requiring unnecessary street crossings Mountable curbs are not appropriate on local streets Casper WY Separated sidewalk is uncluttered, pleasant to walk on Reno NV Parkway separation makes it easy to meet ADA at driveways Salem OR Narrow curbside sidewalks are inadequate in commercial areas Reno NV Crossing the Street Pedestrians want & need to cross the street safely Pedestrians shouldn’t be terrified crossing the street Santa Ana CA Speed Matters High speeds lead to greater chance of serious injury & death Child dart-out: speed is a factor! 150’ First scenario: Speed 25 MPH 100’ = distance covered in 2.5 Driver applies sec. perception/reaction time brakes 100’ 150’ First scenario: Speed 25 MPH Driver applies 50’ stopping distance brakes (wet pavement) 100’ 50’ 150’ First scenario: Speed 25 MPH Result: Nothing happens beyond one scared child, driver & parent! 100’ 50’ 150’ Second scenario: Speed 38MPH 140’ = distance covered in 2.5 Driver applies brakes sec. perception/reaction time 140’ 150’ Second scenario: Speed 38MPH Driver applies brakes 140’ 150’ Second scenario: Speed 38MPH In the last 10’ car slows to 36 MPH 140’ 150’ Second scenario: Speed 38MPH Result: a high speed crash 150’ 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 Conventional design criteria primarily based on: Functional class Design Speed • Complete Streets design begins with Target Speed: – Desirable operating speed – Mobility for motor vehicles – Safety for pedestrians and bicyclists – Usually posted speed limit 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 Islands Reduce crashes by 40% Basic Principle Break long complex crossing into two simpler crossings Poor sign placement Choosing location for island: must have O & D Corvallis OR In this case, apartments across from bus stop and stores Corvallis OR Place cut-through at an angle… Flush median is not much of a refuge Crystal City VA Flush median is not much of a refuge Atlanta GA Replace with a raised island Atlanta GA Intersection Design Small, tight intersections best for pedestrians… Simple, few conflicts, slow speeds AASHTO Ped Guide Intersection Design – Curb Radii – Actual curb radius (R1) – Effective radius (R2) 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 cross + Higher speed turns It’s more than the distance… Effect of large radius on crosswalk Hard to figure out where to cross Effect of large radius on drivers They drive fast… … ignoring pedestrians AASHTO Ped Guide Intersection Design – Curb Radii • Use entire available width to turn into • Select appropriate design vehicle Must consider design vehicles, but don’t choose larger vehicle than necessary We shouldn’t design for the exceptional vehicle Raised islands at intersection separate conflicts Right-Turn Slip Lane: Design for pedestrians Tighter angle 55 to 60 degree angle between vehicle flows Old Way New proposal High speed, head turner Slower vehicle speeds, good low visibility of pedestrians visibility of pedestrians Island with fairly good geometry Turn Lanes Free Flowflow movements… Avoid free- … they are difficult for pedestrians to cross Prevent pedestrian movements Asheville NC Designing Streets for Pedestrian Safety – Interchanges & roundabouts 7-10 Free Flow Turn Lanes Prevent pedestrian movements Free Flow Turn Lanes Expressway Ramps • Right angle intersection where ramp meets cross street • Design urban exits for 20 mph Traffic Signals Signal timing & other simple innovative ideas to minimize pedestrian delay & conflicts Use short signal cycle length Long wait causes stacking: peds wait in street, or 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 Current system: 1. WALK 2. Flashing DON’T WALK * 3. Steady DON’T WALK 1/2 of Americans don’t understand it; Is there a better system? * Flashing red hand/don’t walk is ped clearance interval Very counterintuitive Problem with current system: Pedestrians not sure if they can start during Boston MA flashing don’t walk Problem with current system: Pedestrians not sure if they can start during flashing don’t walk Corvallis OR Pedestrian count-down signal tells pedestrians how much crossing time is left … Springfield OR Pedestrian count-down signal tells pedestrians how much crossing time is left … Reno NV Countdown Clocks Results from San Francisco: 25% Crash Reduction Factor after countdown signals installed Countdown Clocks in MUTCD • 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 Pedestrian signal timing • Old MUTCD recommends using a pedestrian walking speed of 4.0 fps, and at crossings with older or disabled pedestrians, use 3.0 fps • 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 encourage pedestrians to cross without looking? (“false sense of security”) Safety Effects of Marked vs Unmarked Crosswalks at Uncontrolled Locations: Executive Summary and Recommended Guidelines U.S. Department of Transportation by Federal Highway Administration UNC Highway Research and Development Safety Turner-Fairbank Highway Research Center Research Center 6300 Georgetown Pike McLean, VA 22101-2296 March 2002 Conclusions/recommendations 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 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 Markings Once the decision has been made to mark a crosswalk, the crosswalk must be visible to the DRIVER Visible Crosswalks What the pedestrian sees What the driver sees Crosswalk Visibility Crosswalk Marking Types Crosswalk Visibility Longitudinal markings are more visible to driver at a distance Visible Crosswalks Continental Markings What the pedestrian sees What the driver sees Textured xwalks: in theory, more visible. Reality? What the pedestrian sees Corvallis OR What the driver sees Corvallis OR Supplement textured crosswalks with white stripes to ensure visibility Phoenix OR Brick Street with asphalt crosswalks Pedestrian perspective Orlando FL Driver perspective Orlando FL Curb Extensions AASHTO Ped Guide Intersection Design – Sight Lines and Curb Bulbs – Relocate obstructions – Eliminate parking on approaches – Curb extensions when parking remains Curb extensions Most focus has been on reducing crossing distance Other advantages Better visibility (both ways) Traffic calming Room for street furniture Additional on-street parking * * corner is “protected” 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 normal curb line Not 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 intermodalism Transit: bus is most common mode Madison WI Transit: only choice for many people Madison WI Sidewalks should be wide enough to provide space for waiting, boarding and passing. Widen beyond ADA minimum for wheelchair pad Narrow curbside sidewalk provides insufficient space for waiting Honolulu HI Narrow curbside sidewalk provides insufficient space for waiting especially when bus comes & people board Honolulu HI Bus shelter placement: it should not obstruct sidewalk Portland OR Bus shelters must be accessible (grass around it is inaccessible) Honolulu HI Bus shelters must be accessible (grass around it is inaccessible) Honolulu HI Separated sidewalk allows bus shelter placement in planter strip Eugene OR All known crossing techniques apply to transit stops Portland OR Why? 1. Peds can see traffic 2. Bus driver can move 3. Bus doesn’t run over peds Place crosswalks behind bus stop! Madison WI Bicycles Definition: Bike Route System • “Bikeway” is generic term to cover any facility designated for bicycle traffic Facility Selection • Shared Roadway – 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 INDEX Of various types of facilities Major Streets w/o bike lanes 1.28 Minor Streets w/o bike lanes 1.04 * Streets with bike lanes 0.5 Mixed-use paths 0.67 Sidewalks 5.32 (* = shared roadway) 1.00 = median Source: William Moritz, U.W. - “Accident Rates for Various Bicycle Facilities” - based on 2374 riders, 4.4 million miles Bike Lanes: Effect on Rider Characteristics Riders on sidewalk against traffic Riders on road 25% with traffic Total sw riders: 34% 64% 39% 1% Riders on road Riders on sidewalk with traffic against traffic Riders at sites with sidewalks & no bike lanes Bike Lanes: Effect on Rider Characteristics Riders on sidewalk Riders on sw against traffic with traffic 11% Total sw riders: 13% 24% Riders on road 3% with traffic 73% Riders on road against traffic Riders at sites with sidewalks & bike lanes QUESTIONS? COMMENTS? CONCERNS?
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