Here’s a fun-to-peruse map that emerged out of the process for creating Saint Paul’s almost-completed Complete Streets Design Manual. It’s an attempt to make a comprehensive map of Saint Paul’s streets ranked according to all the different safety factors.
Check it out:
This map is a few years old. It was part of an “overlay analysis” that helped to guide the manual, which is under final review and going through the Planning Commission before it gets a public hearing. Check out the whole draft here [warning, very large file].
Here’s the description of the map:
Street Safety Evaluation Map
The Safety Map, Figure 1, represents the relative safety of each street within the city of Saint Paul. A weighted overlay analysis was performed with greater weights applied to the Annual Average Daily Traffic (AADT), speed limit, and road width layers.
- AADT – AADT data ware obtained from MNDOT. The greater the daily traffic flow, the more dangerous the street. Unfortunately, AADT data was not available for every street segment; scores were applied only to the streets for which data were available.
- Speed Limit – Studies have shown that collisions involving pedestrians/bicyclists and vehicles traveling faster than 30mph are significantly more likely to result in death. Therefore, the faster the speed limit, the more dangerous the street.
- Road Width – Road width was deemed to be the third most important factor in terms of safety. As the road width increases, so does the amount of time it takes pedestrians to cross.
- Collisions with Bikes/Pedestrians – Crash data from 2007 through 2011 were compiled from police reports. A kernel density (an area based on number of units) analysis was performed using a search radius distance of 2500 ft. Due to the relatively small sample size of 110 incidents spread across the majority of Saint Paul, the kernel density values are quite small. Five classes were used and reclassified with values of 1 to 5, with higher density values receiving a lower score.
- Pavement Condition Index (PCI) – numerical rating of the pavement condition that ranges from 0 to 100, with 0 being the worst possible condition and 100 being the best possible condition. The PCI provides a measure of the present condition of the pavement based on the distress observed on the surface of the pavement, which also indicates the structural integrity and surface operational condition (localized roughness and safety).
- Missing Sidewalks – While most of the streets include sidewalks on both sides, a few are missing sidewalks on either one side or both sides.
- Bus Routes & Signalized Intersections – This variable rates streets based on the accessibility to bus stops. People are less likely to jaywalk in order to get to a bus stop if they are close to a signalized intersection. Thus, 1⁄4- and 1⁄2-mile buffers were generated around all traffic signals located along a bus route. Streets within 1⁄4 mile were given high score, while those located outside of the 1⁄2 mile buffer were given a low score.
Note: there’s another map, as well, that assesses “transportation” and includes things like transit or missing sidewalks.
It’s sort of unique (and maybe overly optimistic) to try and combine all these factors into once simple scale, but at least you can now glance at the city and see where the dangerous streets are located.