Congestion has become a chronic problem which is the cause of a great number of inefficiencies in the transportation system, such as reducing averaging speeds, increasing trip times, higher fuel consumption and severe environmental damage. All these negative effects are putting at risk the main goal of the current common European Transport Policy: sustainable mobility. Traditionally this problem has been tried to be overcame by increasing the capacity of current infrastructures induce new traffic, and thus reproducing the problem in the mid term. According to this, the new transport policy guidelines are trying to solve the limitation of infrastructures in terms of capacity by maximizing the efficiency in their use, instead of building new infrastructures. One of the most effective strategies is the increase in the average vehicle occupancy rates by providing incentives o the use of the so-called high-occupancy modes.