DDOT's Bicycle Crash Data for 2014

DDOT recently released crash data from 2014. 

This isn't totally accurate becasue it's FARS data, which ignores some fatalities. In this case, Ian Wolfe's fatal crash in 2008 isn't counted because it was investigated by the Park Police and they, it inexplicably seems, do not report fatalities to FARS.

Injuries were up 26.7% from 2013, even while injuries nationally are down or flat (image below shows injuries per year - sorry it kind of sucks). Part of the increase is due to better reporting they state "In 2010, MPD and DDOT significantly improved recorded keeping, training MPD officers, and the crash and FEMS record management system; this resulted in an increase in the number of reported crashes"

It looks like Thursday and Friday are getting safer - good job pre-weekend!

So more cyclists are injured at times when cyclists are cycling. This isn't particularly useful. If we combined it with counts) then we could look at rates. Just to get an idea, I used CaBi data as a proxy for exposure, and then divided the number of injuries per month by the number of CaBi trips per month. There are three problems with this:

1. CaBi use may not perfectly mirror bicycle use

2. CaBi data covers DC, Arlington, Alexandria etc...and it might be different if I weren't so lazy and filtered out the non-DC data

3. The CaBi system isn't static, so some increase in use is due to increased numbers of system bikes, not overall increases in biking.

Also, I had to eyeball the injury number for each month. With all that in mind, what I found was that the month with the highest "rate" was October, followed by Septmeber, July and June. Lowest rate was February, followed by November and December. This is basically the opposite of what I expected. I expected the winter to have the highest rate because of less light, worse road conditions (ice and snow) and the inverse of the safety in numbers effect. So, I'll chalk it up to a methodology flaw (from the list above) until someone does it with better data.

Injuriess also tend to happen where cyclists are riding. Curious. Again, this could be more powerful it combined with counts to get rates. I think CaBi data would be less valid for where, since socio-economic factors start to come into play. 

 

Once again, the kinds of people who we already know are more likely to ride bikes in DC, are also those who are more likely to be in crashes. Add counts, get rates.

 

Comments

[Crickey7]

I think the slight peak in the late afternoon serious injury bar is significant. Dusk is, in my view, a particularly hazardous time. Cyclists assume they that because they can see, that they can also be seen, and that's not entirely accurate.

[Smedley Burkhart]

There's a denominator question there, too, which could be accounted for by the evening commute. A time of day x time of year analysis would shed some more twilight on the issue.

[I forgot]

That the injury "rate" is lowest in the winter and higher in peak riding time probably just indicates that there is a greater proportion of experienced riders in winter than other times. I would hope that experienced riders are less likely to be injured on a per mile basis.

[washcycle]

I thought about that too. And CaBi probably amplifies that. The ratio of experienced to inexperienced cyclists probably differs much more for CaBi than among general cyclists based on season. If that makes sense.

[DE]

I know this is rather obvious and nothing can be done about it, but reported injuries are different than total injuries. I've known of concussions that weren't reported, for instance. Anyway, only reason I bring it up is that the kind of injuries that might be expected to happen in the winter on snow and ice might be this kind of injury. If a seasoned cyclist goes down in the snow and does his collarbone, he's not necessarily going to call an ambulance or the police.

I can't fully understand why the NPS wouldn't report injury data to NHTSA. They're both agencies of the same government. I guess there's no requirement so they don't.

[Uptowner]

Is there any way to compare this to RATES of cycling? Seems like a lot more people are cycling now, so we don't know if it's getting more or less dangerous, based on this data.

[Uptowner]

Posted too quickly. I still don't quite understand which chart shows what. Where is the CaBi data being used? What are the rates?

[Crickey7]

As for the new peak month of October, that is a bit odd. The trend historically had been that ridership begins to tail off in that month (with accident totals reflecting that). Now it kind of looks like the entire fall drop-off occurs between October and November. That could be a indicative of a permanent shift back in the fair-weather rider expiration date, which usually occurs sometime around the first extended cold and wet fall period. Better lights? Integration of riding into daily routines increasing tolerance for some coldness? Anecdotally, I have seen the seasonal drop-off shifting back 2-3 weeks in the last several years.

[DE]

@Crickey: Wet leaves?

Seriously, this kind of exercise is useful for thinking about the situation, but not much as a metric. One of the things it most effectively does is show how much we don't know.

[washcycle]

The CaBi data is not being used in any of the charts. I did that "offscreen" if you will. The rates are sort of meaningless in themselves because they are(per month):

Number of injuries in DC/
Number of CaBi riders in the region

That's useful for comparing months, but the rate is meaningless. Having said that,

October = 0.016%
February = 0.006%

[John Henry Holliday]

@Crickey: random variation in 2014? Warming temps?

Daylight Savings Time ends in early November; the shift means that a cyclist leaving for home at 5 pm is suddenly in darkness the entire ride. That probably marks the end of fair-weather cycling each year. And the end of DST has moved back a week or so over the past few years.

Data issues: what's a "serious injury"? I've been injured badly enough to seek medical attention twice in my commuting career. I've never notified the police.

[Crickey7]

More importantly, why are the folks in Virginia crashing less than those in Maryland?

[washcycle]

These are for crashes in DC. So more Marylanders are crashing in DC than Virginians - likely because of how much easier it is to move between MD and VA.

[DE]

We crash just as much; we're just tougher and report it less. Nah, it's probably fewer VA cyclists than MD ones.

You mean easier to get from MD to DC than from VA to DC? B/c it's somewhat difficult to get from VA to MD by bike.

[washcycle]

Yeah I meant "... MD than VA."

[Crickey7]

So, the conclusion is that DC riders are wusses? It's just a flesh wound?