Busy traffic? Drive slower to go faster, research shows

Mobility Minister Jacqueline Galant ordered the study last year, to be used as a reference in the discussion on maximum speeds on Motorways. The aim was to find out more about the effect on traffic jams, safety and the environment.

The BIVV's main conclusion is that "a progressive reduction of the maximum speed yields the best results, especially during rush hour." When congestion is starting to build up, digital traffic signs should adapt speed limits downward (from 120 km/h to 90, 70 and even 50 or 30 progressively if necessary).

When the maximum speed is reduced, the BIVV calculated that traffic jams will be reduced by 30 percent; the number of deaths by 6 percent and particulate matter emissions by 7 percent. Average speed would climb to 57 km/h, coming from 44. Not only speed matters: it also helps a lot if drivers would not switch lanes constantly.

Talking about variable speed limits, the federal Mobility Minister François Bellot is a supporter of imposing a maximum speed of 130 km/h (80 miles) on Motorways instead of 120 now, but his Flemish colleague Ben Weyts is against. Driving faster triggers more road deaths in the end, Weyts argues.