Speed limits on motorways
08.59
From 2008 to 2009
Commissioned by the Bond Beter Leefmilieu, TML estimated the effects of modified speed limits on Belgian motorways, focusing on travel times, emissions, and road safety. The study analysed the impact of speeds of 100 km/h, 110 km/h and 130 km/h using traffic flow theory and measurement data from 2007.
On behalf of the Bond Beter Leefmilieu, TML did a first assessment of the effects of a modified speed limit on Belgian motorways. The effects on journey times, emissions of particulate matter (PM10), nitrogen oxides (NOx) and carbon dioxide (CO2), and road safety were investigated. Three variants were considered: changing the speed limit for passenger cars to 100km/h, to 110km/h, and to 130km/h.
In a first step, the effect of a modified speed limit on effectively driven speeds was estimated. Measurement data of traffic on Belgian motorways in 2007 was used. Based on considerations from traffic flow theory, the effect on speed was estimated for each measuring point if the speed limit was changed. The effect on travel times, emissions, and road safety was then determined from these modified data points.
The results for Belgium are summarised in the table above. The table shows the difference in costs compared to the base case (maximum speed of 120km/h): negative numbers indicate a decrease in costs, positive numbers indicate an increase in costs.
If travelling time, emissions, and safety alone are considered, reducing the speed limit to 110km/h gives the best results: a decrease in costs of €36 million per year.
Due to the very high cost of increased travel time, lowering the speed limit to 100km/h scores slightly lower (smaller decrease in costs than in the case of lowering the speed limit to 110km/h).
In the case of increasing the speed limit to 130km/h, travel time costs decrease, but emissions and safety costs increase, so that the speed increase scores poorly due to an increase in costs.
On behalf of the Bond Beter Leefmilieu, TML did a first assessment of the effects of a modified speed limit on Belgian motorways. The effects on journey times, emissions of particulate matter (PM10), nitrogen oxides (NOx) and carbon dioxide (CO2), and road safety were investigated. Three variants were considered: changing the speed limit for passenger cars to 100km/h, to 110km/h, and to 130km/h.
In a first step, the effect of a modified speed limit on effectively driven speeds was estimated. Measurement data of traffic on Belgian motorways in 2007 was used. Based on considerations from traffic flow theory, the effect on speed was estimated for each measuring point if the speed limit was changed. The effect on travel times, emissions, and road safety was then determined from these modified data points.
The results for Belgium are summarised in the table above. The table shows the difference in costs compared to the base case (maximum speed of 120km/h): negative numbers indicate a decrease in costs, positive numbers indicate an increase in costs.
If travelling time, emissions, and safety alone are considered, reducing the speed limit to 110km/h gives the best results: a decrease in costs of €36 million per year.
Due to the very high cost of increased travel time, lowering the speed limit to 100km/h scores slightly lower (smaller decrease in costs than in the case of lowering the speed limit to 110km/h).
In the case of increasing the speed limit to 130km/h, travel time costs decrease, but emissions and safety costs increase, so that the speed increase scores poorly due to an increase in costs.
