Physical modelling: On the road to less traffic

The collective travel time lost due to traffic congestion in urban areas could be reduced through optimization of individual travel routes, according to a model published in Nature Communications. The model confirms the notion that traffic congestion in cities is exacerbated by the choices of individual drivers who wish to minimize their travel time.

Although many municipalities in the world have made congestion reduction one of their priorities, increasing the number of roads is often insufficient or impractical, and therefore several initiatives - such as congestion charges, alternative travel modes, carpooling and road lane rationing - have been put in place to modify individuals’ behaviour in order to benefit the collectivity.

Using anonymous cell phone data from millions of people matched with local road network data, Marta Gonzalez, Serdar Colak and colleagues analyze how efficiently people move across five urban areas - Boston, the San Francisco Bay area, Rio de Janeiro, Lisbon and Porto. They model traffic patterns and find that, when drivers make uncoordinated, uninformed (so-called ‘selfish’) travel choices, this results in suboptimal arrangement of traffic in a city. They estimate that the collective time lost due to congestion could be reduced up to 30% on average through optimization of individual travel routes. This would require a small number of drivers to sacrifice their individual commute time by driving on alternate routes in order to relieve congestion.

The authors caution that, although this model system relieves traffic congestion on the whole, average commuting travel time of individual drivers is reduced by only 1-3 minutes.