"Most motorcycle accidents are caused by car drivers who don't see a motorcycle coming turning left into the motorcycle's path."

You must have heard a statement like this. Do you think it's true?

The following two tables are compilations of data from FARS Web-Based Encyclopedia. Table H9-1 is the number of fatal automobile crashes by junction and the number of vehicles involved. Table H9-2 is the corresponding table for fatal motorcycle crashes.

The following six pie charts compare two groups of crashes, automobiles' and motorcycles', in terms of percentage, by junction.

Source: Tables H9-1 and H9-2

While these two tables and six pie charts do not directly show how many of these crashes were caused by cars turning left into a motorcycle's path, they reveal something interesting:

1. Single-vehicle crashes are proportionately more common in fatal automobile crashes than in fatal motorcycle crashes: 54.48% and 46.96 % respectively.
2. The percentage of fatal two-vehicle crashes in intersections is higher for motorcycles than for automobiles: 18.45% and 13.71% respectively.

1. Assuming that single-vehicle crashes are more attributable to operator errors than to some other factors beyond control of the operator, automobile drivers are making more human errors than motorcycle operators.
2. While it appears that a statement such as the one cited at the beginning of this article seems exaggerated, the evidence is seen that in fatal motorcycle crashes, more, in terms of percentage, are involved in multiple-vehicle crashes than in automobile crashes.