I always thought the term "the gore" on expressways referred to crashes caused by people "driving on the gore" but it doesn't. It's actually referring to an old English word that refers to the spear on the road.

There are actually two types of gore on roads -- theoretical gore and the physical gore. Theoretical gores are painted on the roads where motorists shouldn't enter for safety purposes, while the physical gore is the place where they road actually divides.

If you fail to bear left or right and hit the physical gore, you are likely to be gored. And that's why the term probably stuck.