American Roads are more dangerous that British Roads?

November 29, 2011 5:08 PM

In my Internet peregrinations I came across this: 'In 2010 there were 32,788 road deaths in the USA (Source: DfT). This equates to 10.6 road deaths per 100,000 of population and compares to the UK average of 3.1 road deaths per 100,000 of population in 2010.'. I am trying to equate these statistics with relevant land areas vs population.
posted by lungtaworld to travel & transportation (11 answers total)

Well, if you're just asking for the respective population densities, that's easy enough to find:

UK - 660 people/sq mi
US - 83 people/sq mi

I am not sure this is what you are asking, however. Are you asking if the rate of road deaths correlates to the density of an area? Since the density of each country is so variable (Montana vs NYC, for example) I would map land areas that contain an equal number of people, and see if they have a roughly equal number of road deaths. Something like this, but more precise, probably down to the county level. Then I'd take the location info of the road deaths and plot them on the map, and calculate how many are in each area and how much they differ from the expected values.

You'd need the geocoded dataset, of course, but there's no reason this couldn't be done. If that is what you are asking...
posted by desjardins at 5:23 PM on November 29, 2011

By my math:

USA: 8.64 deaths per 1,000 square miles
UK: 20.5 deaths per 1,000 square miles

You might also be interested in "miles of road" as opposed to land area.
posted by mikeand1 at 5:25 PM on November 29, 2011 [1 favorite]

Another thing to consider is that there are more cars per person in the US than the UK (828 per 1000 vs 525 per 1000), and people in the US drive more miles on average. So a more accurate metric to determine which country's roads are more dangerous would be to take the total miles driven and divide it by the number of deaths. I still think this should be broken up by area rather than entire countries due to the density variance.
posted by desjardins at 5:26 PM on November 29, 2011 [1 favorite]

Here's an explanation of my math:

US: 32,788 deaths, 3,794,101 square miles, so total deaths per square mile = 32,788/3,794,101 = 0.0086 or 8.6 deaths per 1,000 square miles.

UK: Total mid-year population of 62,262,000, equal to 622.62 *100,000. So total road deaths = 3.1 * 622.62 = 1,930. Total land area = 94,060 sq mi, so the number of deaths per square mile is 1,930/94,060 = 0.0205, or 20.5 deaths per 1,000 square miles.
posted by mikeand1 at 5:34 PM on November 29, 2011

And there is also much more wilderness in the US than in the UK, just think Alaska.
posted by mareli at 5:35 PM on November 29, 2011

Some stats on US wilderness.

I don't think figuring this out using square miles has any validity given how different the two countries are.
posted by mareli at 5:40 PM on November 29, 2011 [1 favorite]

Not sure exactly what you mean by "equate with relevant land areas"?

The values are already adjusted for population, which is the main thing to control for.

I'm not sure adjusting for the pure area is the best way to go about it; Alaska is really big, but most Alaskans live in Anchorage and have similar commutes and travel patterns to residents of a similar city. In the same vein, road miles helps, but there are a lot of lightly-used rural roads in the US.

My guess at the additional statistic that most helps compare these numbers is Vehicle Miles Travelled, or VMT. (VKT is the metric equivalent that UK authorities would report in.) This is a measure of the total number of miles that people in an area travel in road vehicles for some amount of time (typically a year); it's often represented as VMT per capita, especially when comparing areas with different populations. This table gives VMT values for a number of nations; it's quite old, but VMT per capita changes relatively slowly, so it's not a bad start.

So the US had 10.6 deaths per 100,000 people, and 5,701 vehicle miles travelled per person per year; that's 570.1 million miles per 100K people, and 0.0186 deaths per million miles travelled.

In the UK, there are 3.1 deaths per 100,000 people, and 3,967 vehicle miles travelled per person per year; that's 396.7 million miles per 100K people, and 0.0078 deaths per million miles travelled.

In other words, the US road system is a little over twice as dangerous to its' users on a per-mile basis. There are probably a large number of reasons. Some of them include:
- Drunk driving deaths are much lower in the UK, probably due to a mix of factors from societal pressure to land use (there are more 'local pubs' within walking distance of homes).
- Larger, heavier vehicles that have more inertia and force.
- Difference in training and licensing; the UK test has a pass rate of 43%, while some California DMVs have pass rates ranging from 61% to 83%.
- Difference in health care system; many collisions are not immediately fatal, and the health care response has an effect in the road death rate. One particular issue is that the US has the kind of totally rural areas (much of the Southwest and Plains) that the UK doesn't. If you're involved in a collision in the least accessible area in the UK, you're probably not nearly as far from a hospital capable of handling a trauma victim as compared with West Texas.
- Difference in societal attitudes; not having a car is much more acceptable and practical in the UK, and many people who might otherwise be marginal drivers may choose to not drive.

Here's an interesting discussion on road safety I came across while googling for links.
posted by Homeboy Trouble at 5:55 PM on November 29, 2011 [5 favorites]

Using Wolfram Alpha I get a smaller difference:

0.014 deaths per million miles in the US vs 0.010 deaths per million miles in the UK.

I'm a little skeptical about how comparable this data really is - do the different countries estimate total distance driven similarly? How about what exactly counts as a traffic fatality?
posted by aubilenon at 6:13 PM on November 29, 2011 [1 favorite]

Thanks for all your answers. I never imagined getting so many.
It's rather like comparing apples and oranges.
posted by lungtaworld at 6:32 PM on November 29, 2011

If these include non-motorist deaths, such as pedestrians or cyclists, then I think it would make sense to look at the per capita figure. If its only for motorists, then yes it would make sense to consider the risk per mile driven or time in the car. But if it includes all deaths associated with roads, then I'd want to compare my chances of being killed in this way in USA and the UK simply by being a person living there.

By analogy, I'd be interested in my chances of being shot in the USA or UK, and would not adjust for the number of guns or for number of bullets fired in each country.
posted by Gomoryhu at 8:33 AM on November 30, 2011

I think the relevant metric here is deaths per miles driven, not miles of area of miles of road. That's a better way to directly compare how dangerous driving is in each country.
posted by Aizkolari at 9:45 AM on November 30, 2011