, , ,

When we were in India, I was impressed by the way the traffic moved. No one was moving very fast, and there were very few signals that anyone heeded, but drivers, bikers and walkers made it through. 10 auto-rickshaws would crowd through an intersection, and then, when their number abated even a little, 10 would push through in the other direction. Turning was a negotiation of patience and assertion. The rest would have to acquiesce to your demands. Honking was the accepted method of announcing your presence to all that you encountered on the road. Bikers, carts and horse moved ij their own streams, not much slower than the traffic, and therefore fitting right in with it.

The death toll of this kind of traffic is immense, despite the ballet I witnessed. My father in law was almost hit by a motorcycle that had been hit by an auto-rickshaw. I never saw any such tragedy in this visit, but last time, nine years, ago, I recall cruising by a recent accident on the main highway out of Jaipur. A crowd was gathering around a motorcycle. I have no idea how severe the injuries were. From the average speed on that highway, they could have been grave.

There’s not really a lot of data on traffic and traffic safety in India, but there is pretty good data on traffic safety data in America. Of course, more serious collisions get more serious attention, so I don’t know where all the wrecks happened. But I can get spatial data on 2006 and 2012 fatal collisions. These are two useful years because they are before and after the onset of the great recession. More importantly, they are also before and after perpetually high gas prices and the collapse of traffic miles. It will be be interesting to see if traffic miles resume their climb with the new low gas prices from Saudi Arabia, and how long that boon will last.

What interested me about having point data for fatal wrecks was how much fatal collision were associated with the main, fast highways. While there are 4.5 million miles of roads in the US, there are only 11,000 miles of Highway Performance Monitoring System (HPMS) roads. If you can name a major road in your town, it is probably an HPMS road. It was not difficult to find the proportion of fatal wrecks that were on these HPMS road and the proportion that were, not. I just had to select all collision points by a reasonable radius form the HPMS lines.


ALL FATAL COLLISIONS, 2006 (click to embiggen)



After selecting for all the points within 100 feet of the HPMS roads, I found that about 70% of fatal wrecks were on the HPMS roads. Pretty dangerous for 0.2% of the roads.



While my thesis was that “speed kills” and that the fast roads were of course more dangerous, it could be that the increased fatalities were the result of greater traffic volumes. The greatest number of walker and biker fatalities are where people walk and bike the most, not the places where these activities are the most dangerous. On the other hand, it could be that we are most safe where everyone knows how to use the roads, where to go and what is expected. In other words, local roads. Arterials and the sorts of roads that are in the HPMS are a cauldron of different familiarities and skills; the kinds of places accidents happen. I now have a point layer of the 2009 fatal collisions and the primary/secondary roads. I wonder what they would show. Maybe later I’ll compare across time and scales.

Next week I’ll look at fatal collisions in a different day. I actually started that article months ago, after looking at all the ways that traffic has gotten safer ver the years, and revisiting one way that it didn’t.