Bike lanes reduce the severity of injuries, especially if you're not in them

According to a recent study of New York City bike-car crashes, 

bicyclists on roads with bike lanes who were riding outside the lane had lower likelihood of severe injuries (OR, 0.40, 95% CI 0.16 to 0.99) compared with bicyclists riding on roads without bicycle facilities.

In fact riding outside of a bike lane, on a road with bike lanes had the lowest ratio of severe injuries to total injuries of the 6 scenarios considered. That doesn't mean they were "safer", since it doesn't say anything about how certain facilities might help avoid crashes in the first place. But it might lead to safer design. Ranking the 6 scenarios (after adjusting for confounding variables and ignoring hit-and-run crashes) from highest to lowest severe injury ratio (worst to best) creates this list:

1. No bicycle facility

2, Sharrows

3. Riding outside cycle track

4. Riding inside cycle track

5. Riding inside bike lane

6. Riding outside bike lane

But that isn't really what this study is about. The study is really about how police crash report forms aren't properly designed to capture bicycle crash data. So the researchers grabbed a selected sample of police crash reports from New York City, pulled out the data they think should be included and then created the above analysis as more or a demonstration of the utility of better forms.

On current forms used in 51 states, the only data consistently included was whether or not one party was a "pedal-cyclist" and whether or not they had a helmet on. 

Our research suggests that new bicycle crash-scene variables might be informative for analysis including: 4 bicycle environments (roads, sharrows, bike lanes and cycle tracks); 18 motor vehicle potential impact points including opened car doors and mirrors; 4 bicycle potential impact points; whether in or out of the bicycle environment; 10 bicycle-crash-scene patterns (turn/impact); and motor vehicle types relevant to bicyclists. Having these new variables revealed higher crash frequency on motor vehicle fronts, bicycle fronts, no bike facility, sedan and as sideswipes.

It should be noted that New York City isn't exactly representative. Many of the crashes there involved taxis - hence the prominence of sedans - and I feel like NYC has far more taxis per capita then most other places. But with better forms adopted nationwide, these kinds of local oddities could be accounted for. Anther thing their analysis revealed:

Compared with bicyclists hitting the back of the motor vehicle, opened motor vehicle doors and mirrors resulted in higher risk of severe injury

These results should be taken with a grain of salt. They used a non-random selection of crash reports, with a small sample size, in a city that is very different from the American norm; but the point is that better forms will lead to better data and that better data will lead to better conclusions and designs.

If these new bicycle-crash-scene variables were entered into the existing spreadsheets, bicycling could be analysed with minor injuries as the control and severe injuries as the case. Though not as ideal as a comparison between no injury and injury, using the data in the spreadsheet at least enables a comparison between minor injury and severe injury.

The report notes that such data to could help us decide between bike lanes and cycle tracks and

If environments and crash patterns were coded for motor vehicle/ bicyclist crashes, intersections might be better understood and designed to lessen the looked-but-failed-to-see-errors. Better data leading to better analysis would also inform bicyclist and driver education efforts

They call for something I first heard mentioned years ago - police should use a tablet-computer to enter data on a digital form that asks questions based on what information has been entered so far and provides drop-down lists to make entry better. Is one person a cyclist? then ask about a bike helmet (Instead of asking about safety equipment and including the helmet on a list with car seats) At night? Then ask about lights. Etc...

As one who's poured through FARS data (post forthcoming I swear) and I can attest to the fact that the forms do a terrible job of dealing with bicycle data and are in need of a rewrite. I've spent less time with DC police reports - but even there, there is much room for improvement. (via NextCity)

Comments

[xmal]

Man, it bothers me so much that the numbers around the car aren't aligned to those on a clock! So close . . .

[DE]

But at least they're in order, whereas the bike goes 1 - 2 - 4 - 3. Damn cyclists always have to be different.

[scoot]

Thank you for this link. Yes the statistics published here are easy to misconstrue if you don't look closely. To be meaningful, the denominator really should be the total number of riders, not the number of injured riders. Of course, that data would have been a little tougher to come by...

[washcycle]

scoot, I think that's a different piece of information (albeit a perhaps better one). This piece might be telling us that cyclists riding outside the bike lane are hit at a lower speed, or with less impact, than those hit elsewhere. Cyclists in the bike lane are probably more often involved in doorings, and that might explain why their injuries are more severe.

But, without knowing the rate of injuries, it would be imprudent to make any changes based on this piece of information. By itself, it is interesting but not useful. Combined with the rate of injuries it would be very useful.

[Atlas]

To me, another interesting slice would be to include whether there are parking spaces directly adjacent to the bike lane, cycletrack, or general traffic lane. I feel very safe using a bike lane if there are no parked cars next to me (calvert st bridge), but I only use a bike lane next to parked cars when I am hill-climbing or passing traffic. The danger of getting doored, clipped by a car being driven out of its spot, or having a person pop out from behind two cars is just too much.

I think if the data was sliced by "cycling along parked cars", the results may be less surprising.

[freewheel]

There are so many ways this data could be skewed. For example, there could be 20x more bicyclists riding in the bike lane than riding outside of it.

[Joe D]

Funny someone in DC should comment about NYC's cabs per capita. NYC population / medallions = 616.4; DC population / cab licenses = 104.6. DC has six times as many cabs per capita! (Add in limo licenses, and it's probably even worse.)

Manhattan alone? Maybe you have a case.

[DE]

The ratio of cabs to cars on the road is what you notice though; there are times in NYC (Manhattan, yes) that the street seems to be filled with nothing but cabs, and they're a less common menace here.

[washcycle]

@freewheel, the number of cyclists using a facility shouldn't have any impact on the ratio of severe crashes to total crashes. It would just increase the number of both.

[washcycle]

I think NYC cab medallions are so valuable that a medallioned taxi is never sitting parked. Whereas a licensed driver definitely sleeps (soemtimes while driving). So medallions to licenses probably isn't an accurate representation of the cabs on the road per capita ratio.

[DE]

Also, DC cabs are manufactured without turn signals, making them less noticeable. True story.