The Nouwen Committee (National Platform Paying Differently for Mobility) advised the Cabinet in 2005 about the introduction of a system of road pricing. Part of this advice consisted of a calculation of the expected road safety effects of such a system. In a letter to the Minister of Transport, SWOV advised improving these estimates, which resulted in the Joint Fact Finding (JFF) working party inviting SWOV making these estimates using the available data and results. This report contains the results of SWOV's estimated road safety effects of road pricing. The JFF working party made calculations for 23 road pricing variants. These variants differ in four parameters: the extent of the differentiation (€3.3, 4.9 or 6.8 billion); cost neutrality (at the macro or mesa level i.e. distinguishing between car, van, and lorry; time/place (no differentiation, +11ct/km in the rush hours, or doubling of the differentiating to +5.4 ct/km); and pollution features (not differentiated, by fuel sort, by pollution tax, or the current subdivision). SWOV has attempted to determine the effects of these variables on categories with very different crash rates. These categories are subdivided into 'human', 'vehicle', and 'road'. For example, the crash rate of young novice motorists is considerably higher than that of experienced ones, and the crash rate of motorcyclists is considerably higher than that of motorists. Unfortunately the available data was not sufficient to make the intended subdivisions for many of the relevant road user groups. The reason for this is that the working party used data that was relevant for accessibility and pollution, and these apparently differ substantially from those important for road safety. For the category 'human' it was possible to determine the average number of kilometres travelled by car. This is relevant because travelling a larger number of kilometres generally results in a lower crash rate (per kilometre). The effect of road pricing is that each car will be driven 7-17% less. The quantitative road safety effect this will have cannot yet be calculated. For the category 'vehicle' the (average) seat occupancy (of driver and passengers) appeared to be a relevant quantity for the calculations. We assume here that the risk of injury or being killed per kilometre is proportional to the number of occupants. Road pricing thus leads to a 0-3% more unsafe traffic per vehicle kilometre because the number of occupants per car will increase. For the category 'road' we made a subdivision of the expected traffic volumes on three road types: main roads, rural roads, and urban roads. On all these road types the traffic volume will decrease by 4-16% for all 23 road pricing variants. This is striking because we expected that road pricing of the main road network, which mainly consists of the category 'motorways', would cause a traffic shift to the secondary roads consisting of the categories 'rural' and 'urban' which have a higher crash rate. The smaller traffic volume leads to fewer crashes and casualties. The study concludes that there is insufficient data available to make a sound estimate of the road safety effects of road pricing. Everything that is known indicates that road pricing will result in a possibly substantial road safety improvement of up to 13% fewer road deaths because the number of kilometres travelled on all road types will decrease considerably. To make better estimates we recommend carrying out further studies of the following subjects: - a possible shift of cars to motorcycles; - moped riders, light-moped riders, cyclists; - the secondary road network in greater detail; - the young/the elderly; - behavioural effects such as speeding, overtaking, and headway distances. We finally recommend using 'safety' explicitly as a variable in a number of variants, for example to charge a higher price for risky behaviour, risky vehicles, or risky roads.
Road pricing and road safety
Possible effects on road safety of 23 variants of road pricing
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