Transcript of "#26 Bike Network Planning: Tools for Dealing with Connectivity and Level of Traffic Stress - Furth, Mekuria"
Low Stress Bicycling and Network Low Stress Bicycling and Network Connectivity y Peter G. Furth, Northeastern University Maaza Mekuria Axum Design & Engineering Mekuria, Axum Design & Engineering
Most of the Population has a Low Tolerance for T ffi St T l f Traffic Stress
Classifying the Population by Tolerance for T ffi St T l f Traffic StressStrong &Fearless Enthused &< 1% Confident (7%) C fid Interested but Concerned No Way, No Source: Roger Geller, (60%) How (33%) City of Portland Classifying Network Elements by Level of Traffic Stress (LTS)LTS 1: for children LTS 3: for “Enthused <S 2: for traffic intolerant Confident” adult LTS 4: highest stress
What Is the “Bicycle Network” to an Individual? d d l1. All the streets and paths where one may 1 All the streets and paths where one may legally ride2. Inventory of designated / improved bike 2 Inventory of designated / improved bike facilities3. Set of preferred or suggested routes3 S f f d d4. The set of streets and paths that don’t exceed his / her level of tolerance for traffic stress
Connectivity : Can You Get from A to B without exceeding a specified level of traffic stress? h d f d l l f ff ? San Jose (south central), Stress Level 1
Connectivity : Can You Get from A to B without exceeding a specified level of traffic stress? h d f d l l f ff ? without undue detour? San Jose (south central), Stress Level 1
Detour Criterion Detour CriterionLow‐stress route should not be more than 25% longer than the shortest routeOR (for short trips)OR (f h t t i ) 0.33 mi longer than the shortest route 0 33 mi longer than the shortest route
Criteria for Level of Traffic Stress Criteria for Level of Traffic Stress• Bicycle Level of Service (BLOS 1997) Bicycle Level of Service (BLOS, 1997) – Black‐box formula yields A‐F rating – Data hungry Data hungry – Doesn’t model intersections well• Bi l C Bicycle Compatibility Index (BCI, 1996) tibilit I d (BCI 1996)• Bikeway design criteria in places that have succeeded in attracting the mainstream population
New Set of Criteria New Set of Criteria LTS 1: suitable for children LTS 2: acceptable to traffic Based on Dutch intolerant adult criteria LTS 3: OK for “enthused & Confident” LTS 4 hi h t stress 4: highest t• Segments Segments • Intersection Approaches • Crossings
Weakest Link Principle of Weakest Link Principle of Aggregation gg gThe stress of a route = stress of its most The stress of a route stress of its moststressful link • Different from summing or averaging 1 1 1 4 1 1
SegmentsSegment Type Level of Traffic StressStand‐alone paths LTS = 1Segregated paths S d h LTS = 1 LTS 1(sidepaths, cycle tracks)Bike lanes LTS can vary from 1 to 4Mixed traffic Mi ed traffic LTS can vary from 1 to 4 LTS can ar from 1 to 4
Dutch Criteria (CROW 2007) Lane L Daily traffic D il t ffi Street type and speed limit St t t d d li it configuration (vehicles/day) Urban local Urban Rural local Fast traffic street through street road road 30 km/h (19 30 k /h (19 50 km/h (31 50 k /h (31 60 km/h (37 60 k /h (37 70+ km/h 70 k /h mph) mph) mph) (44+ mph) Two‐way traffic <2500 Mixed traffica Bike laneb or Advisory bike Cycle track with no cycletrackc laned or low‐ centerline 2000–3000 bike laneb or bike lane or speed speed cycle tracke service road 3000–5000 >4000 Bike lane or Bike lane or cycle track cycle trackc Two lanes (1+1) any Bike lane or Bike lane or cycle track cycle trackc Four lanes (2 + any (Does not Cycle track or low‐speed service road 2) or more 2) exist) i t)aFor designated bike routes, a bike lane or advisory bike lane is optional.bMay be an advisory bike lane on road sections with no centerline.cCycle track is preferred if there is parking; cycle track is recommended for designated bike routes track is preferred if there is parking; cycle track is recommended for designated bike routes.dAlthough CROW (2007) gives “mixed traffic” for this cell, the default layout for roads in this category is to mark advisory bike lanes.eCycle track is preferred for designated bike routes.
Criteria for Bike Lanes Alongside a Parking Lane LTS > 1 LTS > 2 LTS > 3 LTS > 4Street idth (thruSt t width (th 1 (n.a.) ( ) 2 or more (n.a.) ( )lanes per direction)Sum of bike lane and 15 ft or 14 or 14.5 13.5 ft or (n.a.)parking lane width more fta lessSpeed limit or 25 mph 30 mph 35 mph 40 mph orprevailing speed or less moreBike lane blockage rare (n.a.) frequent (n.a.)Dimensions aggregate using Weakest Link logic
Criteria for Bike Lanes Not Alongside a Parking Lane Parking Lane LTS > 1 LTS > 2 LTS > 3 LTS > 4Street width (thru 1 2, if directions more than 2, (n.a.)lanes per direction) are separated or 2 without a by a raised separating median medianBike lane width 6 ft or 5.5 ft or less (n.a.) (n.a.) moreSpeed limit or 30 mph (n.a.) 35 mph 40 mphprevailing speed or less or moreBike lane blockage rare (n.a.) frequent (n.a.)
Criteria for Mixed Traffic Street Width 2-3 lanes 4-5 lanes 6+ lanesSpeed LimitUp to 25 mph LTS 1 a or 2 a LTS 3 LTS 430 mph LTS 2 a or 3 a LTS 4 LTS 435+ mph LTS 4 LTS 4 LTS 4 a. Use lower value for streets without marked centerlines or classified as residential and with f l ifi d id ti l d ith fewer th 3 l than lanes; use hi h higher value otherwise.
Traffic Stress on Intersection Approaches – “ k h “Pocket Bike Lanes” k ”Dutch criteria • RT lane must be short• RT lane must begin abruptly• Bik l Bike lane must t continue straight• Wide bike lane• Intersection angle keeps turning speed to 15 km/h to 15 km/h
Criteria for Pocket Bike Lanes Criteria for Pocket Bike Lanes Level of Configuration Traffic StressSingle RT lane up to 150 ft long, starting abruptly while LTS > 2the bik lane continues straight; i tth bike l ti t i ht intersection angle ti lsuch that turning speed is < 15 mph.Single RT lane longer than 150 ft ,starting abruptly LTS > 3while the bike lane continues straight; intersectionangle such that turning speed is < 20 mph.Single RT lane in which the bike lane shifts to the left, LTS > 3but intersection angle and curb radius are such thatturning speed is < 15 mph.Single RT lane with any other configuration; dual RT LTS = 4lanes; or RT lane plus option (through-right) lane
Increased Traffic Stress on Widened Approaches h Added turn lanes (Monroe @ Stevens Creek)
Widened Intersection Approaches Interrupt Low‐Stress Paths h
Barriers• Natural (rivers mountains) RR Freeways: Natural (rivers, mountains), RR, Freeways: Crossings collect traffic, tend to be high stress• Freeways: Added stress from on off ramps Freeways: Added stress from on‐off ramps• Arterials lacking low‐stress approaches with low‐stress crossings l i• Parks and Campuses (!) • Incomplete street grid, forcing traffic to use arterials
A Measure of Connectivity A Measure of Connectivity Percent Trips Connected, by Level of Traffic Stress of Traffic Stress• Trip Table for Home‐to‐Work Trips Number of people traveling from zone i to zone j p p g j Which zone pairs are connected at a given LTS? ( y ) g g p TAZ (traffic analysis zone) = standard geographic unit
TAZ can be too coarse a geographic unit to model bicycle access unit to model bicycle access
Disaggregating Demand from TAZs to Blocks f l k• Origins: in proportion to block population Origins: in proportion to block population• Destinations: in proportion to trip generation factors
Linking Block Centroids to the NetworkLinking Block Centroids to the Network Block centroid, with connectors connectors to surrounding vertices
Home‐Work Trip Connectivity p y Trip Length < 4 mi < 6 mi < 8 mi All LTS 1 0.7% 0.4% 0.3% 0.2% LTS 2 7.7% 4.7% 3.4% 2.2%Before LTS 3 22.6% 16.4% 13.2% 8.9% LTS 4 100.0% 100.0% 100.0% 100.0% Total trips 78,673 136,652 189,439 292,396 Trip Length < 4 mi < 6 mi < 8 mi AllAfter LTS 1 1.7% 1.0% 0.8% 0.5% LTS 2 14.9% 12.7% 11.1% 7.9% LTS 3 27.4% 22.7% 20.0% 14.6% LTS 4 100.0% 100.0% 100.0% 100.0% Total trips 78,673 136,652 189,439 292,396
Acknowledgement• Support from the Mineta Transportation T i Institute • Inspiration from Rails to Trails Rails to Trails Conservancy• Cooperation of the City of San Jose y 44
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