Second Opinion Brussels Ring

Comparison of the congestion and health effects of an enlargement of the ring versus road pricing

The Flemish Government is conducting an Environmental Impact Assessment (EIA) and Social Cost Benefit Analysis (SCBA) study to widen the northern ring road around Brussels (R0).

It is remarkable that in neither the EIA nor the SCBA are the sole effects of the R0 infrastructure developments being analysed. In these comparisons it is always assumed that additional policies will be implemented: the GEN network, road pricing for passenger and freight transport, completion of De Lijn plans, and an increase in bicycle traffic. Given the timing and the costs of these additional measures, however, it remains uncertain whether they will indeed be in place when the widening of the R0 commences.

Therefore in this study and at Groen's request, we have compared a baseline scenario, without additional measures, with a scenario with only road pricing (scenario A), and a scenario in which only infrastructure measures considered (scenario B).

Scenario B is an R0 infrastructure project to achieve the separation of through traffic (three lanes) and local traffic (one or two lanes) on the R0 using parallel roads. It is striking that the traffic forecasts in the EIA study show that the infrastructure project does not significantly increase traffic flow. The largest gain in terms of throughput is achieved by the introduction of road pricing for both freight and passenger transport. In this study, we focus on the possible time gains and the impact on the environment and health. These effects are compared with the potential investment costs of both scenarios. Hence, this is not a full social cost-benefit analysis.

For the calculation of the effects we rely on data from the EIA study. For data that was not available, we formulated our own assumptions. For example, this was the case for the estimation of potential time savings. The possible effects on public transport could not be estimated.

In scenario A (road pricing), there is an overall decrease of transport volumes and congestion. In scenario B (widening of the R0), transport volumes increase and congestion decreases. On the connecting highways, however, congestion increases. In scenario B, the speed gain is much lower than in scenario A.

To calculate the impact on the environment and health the difference in vehicle km is multiplied by emission factors (in kg / vehicle km) for the various pollutants. Then a monetary value is calculated for the impact the pollutants have on humans and nature. Health plays the main role in this monetary valuation. In scenario A there is a decrease in total transport volumes and hence a benefit for society. In scenario B the increase in transport volumes leads to an environmental cost.

Total net present value of journey time and environment for the road, excluding the impact on public transport (million euros)
Travel time gains road transport Traffic on the R0 218 168
  Traffic on the connecting highways 751 -302
  Traffic in Brussels 6625 620
  Traffic in Vilvoorde, Machelen, Zellik, Steenokkerzeel 1838 237
Total 9432 723
Improvement in air quality and climate change   377 -78
Total   9810 645

When we combine the access benefits with the environmental impact, we get an indication of the potential investment costs for the different scenarios which can lead to a break-even for society. This is shown in the table. For scenario A, the investment in road pricing may cost up to 9.8 billion euros. For scenario B, the investment may cost up to 645 million, which is less than the current estimate of the infrastructure works. (1 billion euros).

Because the expected impact of R0 widening on traffic flow is uncertain, a sensitivity analysis was also conducted in which a smaller impact was assumed. When the speed increase was less than expected, the socially acceptable investment in new infrastructure falls to 0.5 billion euros.


Final report (in Dutch)



funded by



Stef Proost (KU Leuven)


Eef Delhaye, Griet De Ceuster


Eef Delhaye

+32 16 74.51.22
reference: 12.48