Mapping Motor Vehicle Collisions in New York City
toddwschneider.com
Mapping Motor Vehicle Collisions in New York City
1–10 of 28 posts
Re: Mapping Motor Vehicle Collisions in New York City
#2Nice work, I am glad that there is a paragraph talking about exposure. Crash trends based strictly on total number of crashes are easy to predict just based on where there is more traffic. Using crashes per vehicle mile traveled for road segments or crashes per entering vehicle for intersections can help tease out trends. Controlling for severity is also important.
When I do a crash analysis for a city, one of the tasks I do regularly for my job, I generate a crash rate and severity index for each intersection. The severity index is basically a weighted average based on severity, non-injury=1, minor injury=3, and severe injury or fatality=8. The crash rate and severity index are divided to create a Severity Rate. While not perfect or statistically valid, it does help identify trends. Also, I am in a rural state so it is rare that there are enough crashes to make any statistically valid conclusions.
Re: Mapping Motor Vehicle Collisions in New York City
#3Drivers mostly hit other things when there's too many things demanding their attention (poor visibility + difficult left turn + busy traffic + bikes + pedestrians = high risk of accidents) so this is probably just a heat map of intersections that are the busiest (in terms of things going on, not necessarily throughput).
I'd like to see a month by month heat map.
Re: Mapping Motor Vehicle Collisions in New York City
#4Nice work, I am glad that there is a paragraph talking about exposure. Crash trends based strictly on total number of crashes are easy to predict just based on where there is more traffic. Using crashes per vehicle mile traveled for road segments or crashes per entering vehicle for intersections can help tease out trends. Controlling for severity is also important. When I do a crash analysis for a city, one of the ta…
What’s the basis for the severity weights? I’d expect the weights to be way more spread out, like 1/10/100/1000. It would definitely not be a good trade off to eliminate nine non-injury crashes at the cost of one additional fatality. But I certainly could be missing something about this sort of evaluation.
Re: Mapping Motor Vehicle Collisions in New York City
#5Nice work, I am glad that there is a paragraph talking about exposure. Crash trends based strictly on total number of crashes are easy to predict just based on where there is more traffic. Using crashes per vehicle mile traveled for road segments or crashes per entering vehicle for intersections can help tease out trends. Controlling for severity is also important. When I do a crash analysis for a city, one of the ta…
What’s the basis for the severity weights? I’d expect the weights to be way more spread out, like 1/10/100/1000. It would definitely not be a good trade off to eliminate nine non-injury crashes at the cost of one additional fatality. But I certainly could be missing something about this sort of evaluation.
Fatalities are a tiny minority of crashes and aren't really interesting to study because usually you basically wind up studying the behavior of drunk people and people who don't wear seat-belts and if you filter those out there's not much data left making meaningful conclusions hard to draw. Fatal accidents are often just normal accidents with a couple aggravating variables on top (e.g. person rear ends semi-truck instead of normal truck or person gets in minor accident but not wearing seat-belt) so it doesn't make sense to fixate one them. Anything that reduces normal crashes by some amount will also affect fatal crashes.
Re: Mapping Motor Vehicle Collisions in New York City
#6I would bet that the shadow/light patterns on Roosevelt Avenue & 94th Street, Queens cause significant visual distractions to drivers and pedestrians.
Re: Mapping Motor Vehicle Collisions in New York City
#7Nice work, I am glad that there is a paragraph talking about exposure. Crash trends based strictly on total number of crashes are easy to predict just based on where there is more traffic. Using crashes per vehicle mile traveled for road segments or crashes per entering vehicle for intersections can help tease out trends. Controlling for severity is also important. When I do a crash analysis for a city, one of the ta…
What’s the basis for the severity weights? I’d expect the weights to be way more spread out, like 1/10/100/1000. It would definitely not be a good trade off to eliminate nine non-injury crashes at the cost of one additional fatality. But I certainly could be missing something about this sort of evaluation.
Generally it is based on the relative costs of a non-injury vs other injury types. So the weight is equal to cost of fatality divided by cost of non-injury. Keep in mind that these values vary from region to region. We use the 1, 3, 8 grouping because the State uses it and by being consistent we can compare different areas more easily.
Re: Mapping Motor Vehicle Collisions in New York City
#8Earlier quoted context omitted.
What’s the basis for the severity weights? I’d expect the weights to be way more spread out, like 1/10/100/1000. It would definitely not be a good trade off to eliminate nine non-injury crashes at the cost of one additional fatality. But I certainly could be missing something about this sort of evaluation.
Fatalities are a tiny minority of crashes and aren't really interesting to study because usually you basically wind up studying the behavior of drunk people and people who don't wear seat-belts and if you filter those out there's not much data left making meaningful conclusions hard to draw. Fatal accidents are often just normal accidents with a couple aggravating variables on top (e.g. person rear ends semi-truck in…
Drunk drivers and people that don't wear seat belts are still worth reviewing. While there are rarely engineering solutions to the fatalities that result, it can help inform education programs and initiatives. Amazingly, buckle-up and don't drive drunk advertising can make a difference.
Re: Mapping Motor Vehicle Collisions in New York City
#9Lots of crashes in Hell's Kitchen. That area is full of people going out to bars and restaurants, tiny sidewalks, and lots of impatient drivers trying to get through Manhattan to New Jersey.
Re: Mapping Motor Vehicle Collisions in New York City
#10I'm not sure what constitutes a "collision", but in 2015, I lived on Lexington between 121 and 122 and saw the investigation of a Hit and Run of a homeless man. I talked to a couple of the witnesses who saw it happen.
This incident was at Lexington and 123rd. In the data, I do not see this incident.