Mapping where crashes occur - Spotlight on Doylestown

Your town probably has at least one “bad” intersection or road. Maybe one area in particular immediately came to mind or maybe you’ll notice it the next time you’re out driving around town. Either way, I’m confident that anyone who has routinely driven, biked, or walked around their town has been frustrated by a seemingly dangerous intersection or road. In some cases, it’s due to confusing or conflicting traffic markings and signage. Sometimes it’s a speed limit that makes no sense or a crosswalk placed in an almost inexplicable manner. Or maybe the issue isn’t obvious to you but you’ve seen far too many crashes in a particular location and know something must be wrong.

At Evident Forensics, we love using data and hard evidence to get to the bottom of an issue. That’s why, today, we’re sharing a fantastic tool for discovering local intersections and roads that have experienced a disproportionate amount of crashes. 

Visualizing where crashes have occurred

According to their website, the Delaware Valley Regional Planning Commission (DVRPC) “serves as the regional planning agency for the nine-county, bi-state, Greater Philadelphia area, providing guidance and assistance to build a sustainable and livable region.” Transportation safety is one of the many objectives of the DVRPC and, as part of that effort, they  created an interactive map (called the Crash Data Viewer) showing the location of each crash in the region from 2014 to 2022 (hopefully 2023+ is in the works over there). 

The map uses a compilation of traffic crash reports from police departments around the region and includes a limited amount of additional information about the crash - such as the severity of injuries involved and if a pedestrian or bike was involved.  Although the data set is far too limited to understand what happened in any of the crashes, or what can be done to prevent future crashes, it does provide some of the best insights we can get into WHERE the crashes have happened. With that knowledge, we can identify the intersections and roads that experience disproportionately frequent and severe crashes. With the problem areas identified, an immediate review of the problem area can be performed to look for likely causes of the issue.  The area can also be targeted for in-depth investigations of any future crashes in order to provide a complete understanding of the factors that contributed to the crash.

With that in mind, let’s look at some maps.

If you’d prefer to skip right to the DVRPC Crash Data Viewer website, you can find it here.

An overview of the full region covered by the DVRPC Crash Data Viewer. While zoomed out, the colors on the map represent the number of crashes that occurred at that location.

The Crash Data Viewer allows you to zoom in to all of the local area streets and roads. As you zoom, the color-coding changes from the number of crashes in the area to the severity of the crashes. See below.

Each crash is color-coded on the map to indicate the reported severity of the crash. Fatal crashes are shown in the darkest shade of red and crashes with no reported injuries and minor damage are plain white. 

Getting even more local

Evident Forensics is located in Doylestown Pennsylvania so that’s where we’ll focus on in today’s post. The Crash Data Viewer allows us to explore the map, and a few associated crash statistics, by selecting individual counties, municipalities, or a specific address.  Selecting "Municipality” and “Doylestown Township” in the search bar on the top right corner of the Crash Data Viewer zooms the map on the township and narrows the reported statistics to crashes in the township.

Note: Those familiar with the area will know that there’s a Doylestown Township and a Doylestown Borough. This post will be limited to the township to avoid confusion.

Another feature of the map allows us to show ALL crashes in the region or to only show the crashes that were reported as severe or fatal (DVRPC uses the acronym KSI those crashes).

A word of caution: This data comes from traffic crash reports prepared by a responding police officer. These reports rarely provide more than superficial level details about the incident and police officers can’t be expected to provide a clinical assessment of injury severity. For example, an officer responding to a crash may mark on their report that there were no injuries or that the injuries were minor while a medical doctor may later find that there were injuries or that the injury was more severe than was apparent to the officer. Keep an eye out for future blog posts on this issue and a discussion on the need for thorough investigations that go deeper than crash reports.

The first map below shows ALL crashes in town from 2018-2022, the second map shows only the most severe (“KSI”) crashes, and the final image shows the number of crashes and types of reported crashes in town from 2018-2022.

We’ll be spending more time studying the DVRPC’s Crash Data Viewer but, for now, it’s enough to introduce it and how it works. If you have a “bad” intersection or road in mind, take a look through the map (the link is above the first image in this page) and see if you can find how many crashes have happened there and how severe they reportedly were. Keep in mind that this map only shows crashes that were reported to the police and won’t show all of the near-misses where a crash was avoided.

What’s the point in tracking all these crashes?

Human, vehicle, and environment. Those are the three basic elements involved in every crash. We most frequently hear about the human element in a crash (e.g. drunk drivers, speeding, failed to yield, etc.) and those discussions almost always focus on responsibility or liability. Sometimes the question of liability shifts to the vehicle element (e.g. defective parts, recalls, a mechanic that caused a dangerous condition, etc.). But, when crash investigators and accident reconstructionists talk about the environmental element, the discussion often focuses on the weather and the terrain (e.g. a hill, tree, or bend in the road obstructing a driver’s line of sight). What’s often overlooked in the environmental discussion is the design of the street/road itself.  Future blog posts will dig into the topic of street/road design and how it influence’s driver behavior.

Looking to read more about road design? Many more articles on the topic can be found on the Strong Towns website.