The Impact of Trajectory Speed Control
14091
2014
TML conducted an impact assessment of the section control along the A10/E40 motorway between Brussels and Ghent, based on traffic data from the data warehouse of Verkeerscentrum Vlaanderen. By analysing traffic safety with accident data from the Belgian police, TML gained insight into the impact of this measure on traffic behaviour and safety.
Trajectory speed control measures the travel time of a vehicle between two fixed points along a road and derives the average speed from those observations. In this impact assessment, we studied trajectory speed control along the A10/E40 motorway between Brussels and Ghent. We used traffic data collected by the Verkeerscentrum Vlaanderen in their data warehouse. Unlike previous studies on trajectory speed control, this data is quite detailed, as it contains information from every five minutes for more than two years. In addition, we also analysed road safety thanks to accident data we received from the Belgian police.
We briefly sum up our main conclusions. Trajectory speed control has no impact on road capacity at that location. There is a noticeable drop of around 4% in the speed of cars and vans. More spectacular is the decrease of about 25% to 30% in the speed deviations of these vehicles, from which we infer, among other things, that traffic flow is more stable thanks to the measure. We also observe a positive effect on road safety: the number of accidents falls by about 15%, implying that 23% fewer cars are involved. Moreover, we estimate a decrease of about 29% light offenders and an even more pronounced decrease of about 78% heavy offenders. Given the initial roll-out costs and the direct benefits of the fines, the measure appears to have an initial benefit-cost ratio of about 9.7:1 for the first year. Thereafter, the benefit-cost ratio is higher, as section control requires only maintenance costs for the following years.
Trajectory control is a useful measure to reduce accidents without impeding traffic flows. Given the nature of the measure, we also encourage its use on non-motorways, such as urban ring roads and secondary roads. Note that fixed flashing cameras are still very useful, for example in built-up areas. We believe a good policy consists of a healthy combination of both approaches to enforcement plus sensitising road users by explaining the motivation and effects of these measures.
Trajectory speed control measures the travel time of a vehicle between two fixed points along a road and derives the average speed from those observations. In this impact assessment, we studied trajectory speed control along the A10/E40 motorway between Brussels and Ghent. We used traffic data collected by the Verkeerscentrum Vlaanderen in their data warehouse. Unlike previous studies on trajectory speed control, this data is quite detailed, as it contains information from every five minutes for more than two years. In addition, we also analysed road safety thanks to accident data we received from the Belgian police.
We briefly sum up our main conclusions. Trajectory speed control has no impact on road capacity at that location. There is a noticeable drop of around 4% in the speed of cars and vans. More spectacular is the decrease of about 25% to 30% in the speed deviations of these vehicles, from which we infer, among other things, that traffic flow is more stable thanks to the measure. We also observe a positive effect on road safety: the number of accidents falls by about 15%, implying that 23% fewer cars are involved. Moreover, we estimate a decrease of about 29% light offenders and an even more pronounced decrease of about 78% heavy offenders. Given the initial roll-out costs and the direct benefits of the fines, the measure appears to have an initial benefit-cost ratio of about 9.7:1 for the first year. Thereafter, the benefit-cost ratio is higher, as section control requires only maintenance costs for the following years.
Trajectory control is a useful measure to reduce accidents without impeding traffic flows. Given the nature of the measure, we also encourage its use on non-motorways, such as urban ring roads and secondary roads. Note that fixed flashing cameras are still very useful, for example in built-up areas. We believe a good policy consists of a healthy combination of both approaches to enforcement plus sensitising road users by explaining the motivation and effects of these measures.
