Low Stress Bicycling and NetworkLow Stress Bicycling and Network Connectivity y

Peter G. Furth, Northeastern University

Maaza Mekuria Axum Design & EngineeringMaaza Mekuria, Axum Design & Engineering

Most of the Population has a Low T l f T ffi StTolerance for Traffic Stress

Classifying the Population by T l f T ffi StTolerance for Traffic Stress

Strong & Fearless Enthused &

C fid (7%)

Interested but Concerned (60%)

No Way, No How (33%)

< 1% Confident (7%)

Source: Roger Geller, City of Portland

Classifying Network Elements byClassifying Network Elements by Level of Traffic Stress (LTS)

LTS 1: for childrenLTS 2: for traffic intolerant

LTS 3: for “Enthused & Confident”

adult LTS 4: highest stress

What Is the “Bicycle Network” to an d d lIndividual?

1 All the streets and paths where one may1. All the streets and paths where one may legally ride

2 Inventory of designated / improved bike2. Inventory of designated / improved bike facilities

3 S f f d d3. Set of preferred or suggested routes

4. 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 Bh d f d l l f ff ?without exceeding a specified level of traffic stress?

San Jose (south central), Stress Level 1

Level of Traffic Stress 1 (LTS 1) Islands

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SJSU Rooted Tree LTS 2

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Level of Traffic Stress 2 (LTS 2) Islands

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Connectivity : Can You Get from A to Bh d f d l l f ff ?without exceeding a specified level of traffic stress?

without undue detour?

San Jose (south central), Stress Level 1

Detour CriterionDetour Criterion

Low‐stress route should not be more than

25% longer than the shortest route

OR (f h t t i )OR (for short trips)

0 33 mi longer than the shortest route0.33 mi longer than the shortest route

Criteria for Level of Traffic StressCriteria 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 tibilit I d (BCI 1996)• Bicycle Compatibility Index (BCI, 1996)

• Bikeway design criteria in places that have succeeded in attracting the mainstream population

New Set of CriteriaNew Set of Criteria

LTS 1: suitable for childrenLTS 1: suitable for childrenLTS 2: acceptable to traffic

intolerant adult Based on Dutch criteria

LTS 3: OK for “enthused & Confident”

LTS 4 hi h t t

• Segments

LTS 4: highest stress

• Segments 

• Intersection Approaches 

• Crossings

Weakest Link Principle ofWeakest Link Principle of Aggregationgg g

The stress of a route stress of its mostThe stress of a route = stress of its most stressful link

• Different from summing or averaging

1 1 1 4 1 1

SegmentsSegmentsSegment Type Level of Traffic Stress

Stand‐alone paths LTS = 1

S d h LTS 1Segregated paths (sidepaths, cycle tracks)

LTS = 1

Bike lanes LTS can vary from 1 to 4

Mi ed traffic LTS can ar from 1 to 4Mixed traffic  LTS  can vary from 1 to 4

Dutch Criteria (CROW 2007)L D il t ffi St t t d d li itLane configuration

Daily traffic (vehicles/day)

Street type and speed limit

Urban local street

Urban through street

Rural local road

Fast traffic road

30 k /h (19 50 k /h (31 60 k /h (37 70 k /h30 km/h (19 mph)

50 km/h (31 mph)

60 km/h (37 mph)

70+ km/h (44+ mph)

Two‐way traffic with no centerline

<2500 Mixed traffica Bike laneb or cycletrackc

Advisory bike laned

Cycle track or low‐speed2000–3000 bike laneb orcenterline speed service road

2000–3000 bike lane or cycle tracke

3000–5000

>4000 Bike lane or  Bike lane or cycle track cycle trackc

Two lanes (1+1) any Bike lane or cycle track

Bike lane or cycle trackc

Four lanes (2 + 2)

any (Does not i t)

Cycle track or low‐speed service road2) or more exist)

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 routesCycle 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 > 4

St t idth (th 1 ( ) 2 ( )

Lane

Street width (thrulanes per direction)

1 (n.a.) 2 or more (n.a.)

Sum of bike lane and 15 ft or 14 or 14.5 13.5 ft or (n.a.)parking lane width more fta less

Speed limit or prevailing speed

25 mph or less

30 mph 35 mph 40 mph or moreprevailing speed or less more

Bike lane blockage rare (n.a.) frequent (n.a.)

Dimensions aggregate using Weakest Link logic

Criteria for Bike Lanes Not Alongside a Parking LaneParking Lane

LTS > 1 LTS > 2 LTS > 3 LTS > 4

Street width (thru lanes per direction)

1 2, if directions are separated

by a raised

more than 2, or 2 without a

separating

(n.a.)

by a raised median

separating median

Bike lane width 6 ft or more

5.5 ft or less (n.a.) (n.a.)more

Speed limit or prevailing speed

30 mph or less

(n.a.) 35 mph 40 mph or more

Bike lane blockage rare (n.a.) frequent (n.a.)

Criteria for Mixed Traffic

Street Width

Speed Limit2-3 lanes 4-5 lanes 6+ lanes

Up to 25 mph LTS 1 a or 2 a LTS 3 LTS 4

30 mph LTS 2 a or 3 a LTS 4 LTS 430 mph LTS 2 or 3 LTS 4 LTS 4

35+ mph LTS 4 LTS 4 LTS 4

a. Use lower value for streets without marked centerlines or l ifi d id ti l d ith f th 3 l hi hclassified as residential and with fewer than 3 lanes; use higher

value otherwise.

Traffic Stress on Intersection h “ k k ”Approaches – “Pocket Bike Lanes”

Dutch criteria • RT lane must be shortshort

• RT lane must begin abruptlyBik l t• Bike lane must continue straight

• Wide bike lane• Intersection anglekeeps turning speed to 15 km/hto 15 km/h

Criteria for Pocket Bike LanesCriteria for Pocket Bike Lanes

Level ofConfiguration

Level of Traffic Stress

Single RT lane up to 150 ft long, starting abruptly while th bik l ti t i ht i t ti l

LTS > 2the bike lane continues straight; intersection angle such that turning speed is < 15 mph.Single RT lane longer than 150 ft ,starting abruptly LTS > 3while the bike lane continues straight; intersection angle 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 that turning 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 hApproaches

Added turn lanes(Monroe @ Stevens Creek)

Widened Intersection Approaches hInterrupt Low‐Stress Paths

Stress at Crossings – Apparent Safe Routes Crossing Winchester Avenueg

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Stress at CrossingsStress at Crossings

Criteria for CrossingsCriteria for CrossingsNO MEDIAN REFUGE Width of Street Being Crossed

Speed Limit Up to 3 lanes 4 - 5 lanes 6+ lanesUp to 25 mph LTS 1 LTS 2 LTS 430 mph LTS 1 LTS 2 LTS 435 mph LTS 2 LTS 3 LTS 440+ LTS 3 LTS 4 LTS 4

WITH MEDIAN REFUGEWidth of street being crossed

Speed Limit Up to 3 lanes 4 - 5 lanes 6+ lanesUp to 25 mph LTS 1 LTS 1 LTS 230 mph LTS 1 LTS 2 LTS 335 mph LTS 2 LTS 3 LTS 440+ LTS 3 LTS 4 LTS 4

With Crossing Effect – Winchester becomes a barrier without any low‐stress crossingy g

ADECCalGIS 2012 

Sacramento, CA  26

San Jose Street Network Stress Classification

ADECCalGIS 2012 

Sacramento, CA  27

Distribution of Segment Miles by Level g yof Traffic Stress

Stress Level Miles Miles (percent)Lowest 1 2131 64%

Low 2 115 3%Low 2 115 3%Medium 3 276 8%

High 4 678 20%Prohibited 5 134 4%Prohibited 5 134 4%

Total 3334 100%

San Jose Street Network Stress Level 1

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San Jose Street Network Stress Level 2

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San Jose Street Network Stress Level 3

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San Jose Street Network Stress Level 4

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BarriersBarriers

• 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 l ilow‐stress crossings

• Parks and Campuses (!) 

• Incomplete street grid, forcing traffic to use arterials

Incomplete Street Grid as Barrier

Permeable Barriers Can Be a Key to Connectivity and Low Stress

Downing Ave – Westfield Ave @ Hwy 17

Level of Traffic Stress 2 (LTS 2) Islands

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Slate of Possible Improvements

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Resulting Network for LTS < 2

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A Measure of ConnectivityA Measure of Connectivity

Percent Trips Connected, by Level of Traffic Stressof Traffic Stress

• Trip Table for Home‐to‐Work TripsNumber of people traveling from zone i to zone jp p g j

Which zone pairs are connected at a given LTS?

TAZ (traffic analysis zone) = standard geographic ( y ) g g punit

TAZ can be too coarse a geographic unit to model bicycle accessunit to model bicycle access

Disaggregating Demand f l kfrom TAZs to Blocks

• Origins: in proportion to block populationOrigins:  in proportion to block population

• Destinations:  in proportion to trip generation factorsfactors

Linking Block Centroids to the NetworkLinking Block Centroids to the Network

Block centroid, with connectorsconnectors  to surrounding vertices

Home‐Work Trip Connectivityp yTrip 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%

LTS  3  22.6% 16.4% 13.2% 8.9%

LTS  4  100.0% 100.0% 100.0% 100.0%

Before

Total trips 78,673  136,652  189,439  292,396 

Trip Length < 4 mi < 6 mi < 8 mi All

LTS 1  1.7% 1.0% 0.8% 0.5%AfterLTS  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 

AcknowledgementAcknowledgement

• Support from the MinetaT iTransportation Institute 

• Inspiration from Rails to TrailsRails to Trails Conservancy

• Cooperation of the City of San Josey

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