Overtaking Lorries

Is it dangerous to overtake a truck?


People often are intimidated by the big trucks on highways, and get queasy when being next to one in the other lane. After all, the odds of a regular passenger car are small when the going gets tough.

On the other hand truck drivers have more experience behind the wheel than folks whose job does not include driving, and thus should be better prepared to handle a vehicle.

So, is it more dangerous to overtake (or be overtaken by) a truck or a car? A look at the numbers can help answer the question; but no ready-made statistics exist, so we'll have to build our own.

Ideally, one would look up how many passing manoeuvers between cars and trucks are executed in a given timeframe, and relate them to the number of accidents during overtaking involving cars and trucks. This data could be then be compared to the same figures for car/car manoeuvers.

Great Britain's Department for Transport puts up a great deal of statistics, including access to raw data for the last five years. This proved invaluable for figuring out how many overtaking accidents had taken place - some downloads and a couple of perl scripts later, it was clear that there were 6395 overtaking accidents between two cars, and 1351 overtaking accidents between a car and a truck.

Of course there are no statistics of overtaking manoeuvres (that would be a bit daft), but a good approximation is the number of kilometers driven. Conveniently enough, the Transport Statistics Great Britain 2009 Edition has them listed by category on page 128: in the last five years cars accounted for 2'000 billion vehicle kilometers, and trucks for 145 billion vehicle kilometers.


Putting it all together,this is the result:

  Billion kilometers driven Accidents with cars during overtaking Million kilometers per accident
Cars 2'003.7 6395 313
Trucks 145.6 1351 108


The picture which emerges is pretty clear: cars are almost three times as likely to get into an accident during an overtaking manoeuver with a truck than with another car. Be carefully when passing those lorries.


Note: the accident statistics take into account all accidents between 2005 and 2009, and the total number of kilometers driven relates to the years 2004 to 2008 (newer data wasn't available at the time of this writing). Given that the data is summarized over 5 years, any possible variations in driving volume or overtaking crashes should not have a significant effect on the bottom line.


A kind of freakonomics, isn't it?