Identifying High Injury Density Corridors and Areas for Targeted Safety Improvements to Reduce Severe and Fatal Pedestrian Injuries: A Methodology

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1 Background The December 2010 Executive Directive 10-03: Pedestrian Safety In San Francisco established targets for the reduction of serious and fatal pedestrian injuries in San Francisco of 25% by 2016 and 50% by The Directive also directed city agencies to both implement several short term actions and coordinate planning to achieve these targets. One early task of the Pedestrian Safety Task Force has been to identify high injury density corridors and areas to prioritize targeted engineering and enforcement efforts. This document provides a summary of the methodology and findings to date of the Data Subcommittee, which will be reviewed in the Pedestrian Safety Task Force Subcommittees in the coming weeks. Methodology Corridor-level and area-level analysis is necessary for efficient and effective pedestrian injury prevention. 1,2,3 Prioritization based on high injury intersections alone typically identify and address only a very small overall proportion of vehicle-pedestrian collision injuries. For example, for a given year the top 10 intersections with the highest numbers of pedestrian injuries in San Francisco account for <3% of the total pedestrian injuries. Furthermore, because pedestrian injuries are relatively rare events at an individual intersection, there can be a high degree of variability at individual intersections from year-to-year. However, there are evident corridor- and area-level patterns of injury that represent a much larger share of injuries. The concentration of pedestrian injury collisions along corridors and in areas represents the aggregation of established environmental-level risk factors including pedestrian activity, traffic volumes and traffic speeds. Interventions targeting areas and corridors can address the factors contributing to injuries at multiple streets and intersections. We used data for (the most recent annual data available) from the Statewide Integrated Traffic Records System (SWITRS), managed by the California Highway Patrol, for this analysis. 4 We included all pedestrian injuries resulting from a collision between a vehicle and a pedestrian in our analysis, for a total of 3,883 pedestrian injuries (383 of which were severe) and 97 fatalities (n=16 pedestrian injuries were not able to be geocoded and were thus excluded from the analysis). For this analysis, we weighted severe and fatal injuries a focus of prevention efforts as described in the Executive Directive - by multiplying those counts times 3. We then conducted the following steps using ArcGIS mapping software to identify high injury density areas and corridors. 1 Morency P, Cloutier MS From targeted black spots to area-wide pedestrian safety. Injury Prevention 12: Wier M, Weintraub J, Humphreys E, Seto E, Bhatia R An area-level model of vehicle-pedestrian injury collisions with implications for land use and transportation planning. Accident Analysis & Prevention 41: Loukaitou-Sideris, A., Ligget, R., Sung, H.G., Death on the Crosswalk: A Study of Pedestrian-Automobile Collisions in Los Angeles. Journal of Planning Education and Research 26: More information regarding SWITRS and how to access this data available at: 1

2 1) Map pedestrian injury counts to street segments by aggregating injury counts (initially assigned to intersections based on primary and secondary streets in SWITRS) and then assigning them to their adjoining street segments. Note that this approach results in injuries being counted on each of the streets that intersect at that intersection. 2

3 2) Identify potential high injury density corridors, defined by proximate street segments with weighted counts >9. We determined the cut-point of weighted counts >9 based on the distribution of the data; this cut-point also includes intersection-level hotspots with three or more severe/fatal collisions in the 5-year period. We used a mapping method that takes into account the area density of the mapped, weighted injuries and added a high injury density zone (in light blue) to the map that highlights area-level concentrations of injury. We also calculated summary statistics for each corridor (see Table 1, page 4-5). The identified corridors in blue represent 5.2% of San Francisco s street miles, and include 55% of all severe and fatal injuries and 51% of total pedestrian injuries in the five-year period. 3

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5 3) Corridor-level Summary Statistics: The following table provides summary statistics for each corridor highlighted in blue in the preceding maps. As stated under step 1 of the methods, please note that this approach results in injuries being counted on each of the streets that intersect at that intersection. Table 1. High Injury Density Corridor Summary Statistics: San Francisco, CA ( ) Street* Cross Street (1) Cross Street (2) High Injury Corridor Length (Miles)** Severe/ Fatal Injuries Per Mile Total Injuries Per Mile Total Weighted Injuries Per Mile San Francisco (Total 1, Street Length) High Injury Density Corridors (Total) 04TH MARKET BLUXOME TH MARKET BRANNAN TH MARKET MCLEA TH SAN BRUNO CASTRO TH CAPP DIAMOND TH (1) LINCOLN ORTEGA TH (2) ORTEGA VICENTE TH (3) VICENTE WINSTON TH (4) WINSTON JUNIPERO SERRA BAY THE COLUMBUS EMBARCADERO BROADWAY FRONT POWELL BUSH JONES OCTAVIA CALIFORNIA CUSHMAN FRANKLIN CASTRO 17TH 19TH CHARLES J MCALLISTER MARKET BRENHAM CHURCH HERMANN CHULA COLLINGWOOD MARKET 19TH COLUMBUS BAY KEARNY CYRIL MAGNIN OFARRELL MARKET DIVISADERO CLAY TURK DR CARLTON B MCALLISTER GROVE GOODLETT (POLK) EDDY CYRIL MAGNIN VAN NESS ELLIS MARKET/STOCKT VAN NESS ON FELL MARKET/POLK VAN NESS FULTON HYDE LARKIN GEARY (1) MARKET LAGUNA GEARY (2) LAGUNA DIVISADERO GEARY (3) DIVISADERO COOK GEARY (4) COOK 09TH

6 GEARY (5) 09TH 22ND GENEVA (1) SANTOS MOSCOW GENEVA (2) PARIS OCEAN GOLDEN GATE MARKET/TAYLOR VAN NESS GRANT SUTTER MARKET/OFAR RELL GROVE MARKET/HYDE VAN NESS GUERRERO 15TH 20TH HAYES MARKET VAN NESS HOWARD NEW MONTGOMERY LAFAYETTE HYDE SACRAMENTO MARKET/GROV E JONES SUTTER MARKET KEARNY PACIFIC MARKET LARKIN SUTTER MARKET LEAVENWORTH SUTTER MCALLISTER LOMBARD BUCHANAN RICHARDSON MARKET (1) STEUART 04TH/STOCKTO N/ELLIS MARKET (2) 04TH/STOCKTON/ 10TH/POLK/FEL ELLIS L MARKET (3) 10TH/POLK/FELL DUBOCE/BUCH ANAN MARKET (4) DUBOCE/BUCHAN COLLINGWOOD AN MASON SUTTER MARKET/TURK MCALLISTER MARKET VAN NESS MISSION (1) SPEAR 08TH MISSION (2) 08TH 20TH MISSION (3) 20TH SANTA MARINA MISSION (4) TRUMBULL NIAGARA MONTGOMERY SUTTER MARKET MYRTLE OCEAN GENEVA ASHTON OFARRELL MARKET/GRANT FRANKLIN PALOU RANKIN JENNINGS PAUL SAN BRUNO WHEAT PINE MASON OCTAVIA POLK SACRAMENTO MARKET/FELL POST MARKET FRANKLIN POWELL SUTTER ELLIS SAN BRUNO GAVEN PAUL SOUTH VAN NESS MARKET 12TH STOCKTON GREENWICH MARKET SUNSET (1) IRVING NORIEGA SUNSET (2) NORIEGA SANTIAGO SUNSET (3) SANTIAGO YORBA SUTTER MARKET GOUGH TARAVAL FUNSTON 41ST

7 TAYLOR SACRAMENTO MARKET/GOLD EN GATE THE EMBARCADERO (1) BROADWAY HOWARD THE EMBARCADERO (2) HOWARD BRANNAN TURK MARKET PIERCE VALENCIA 16TH 24TH VAN NESS (1) UNION POST VAN NESS (2) POST MARKET * Identified corridors exceeding two miles in length were partitioned into shorter corridors based on patterns in injury density along that corridor. ** Street length includes all streets in San Francisco including streets managed by non-ccsf agencies such as Caltrans or the U.S. National Parks Service. Please contact Megan Wier (megan.wier@sfdph.org or ) with questions or comments regarding this methodology. 7