The New Italian Road Code and the Virtues of the ‘Shame Lane’

In July 2003 a new Road Code was approved by the Italian parliament. Among many reforms whose validity is not questioned here, the new law states that on three-lane motorways the right lane should not be reserved anymore to slow vehicles alone. As in two-lane roads, all vehicles must now drive on the right lane, as long as it is not occupied by other vehicles. The model developed in this paper casts doubts on the validity of such a change, suggesting that the old rule generally performs better, in terms of number of accidents, average speed and motorway capacity, than the new one. This conclusion is shown to be extremely robust to refinements of the main assumptions concerning driving attitudes and the stochastic arrival of accidents.