Steen Solvang Jensen, Mattias Ketzel & Mikael Skou Andersen 2010: Road Pricing, Air Pollution and External Costs. National Environmental Research Institute, Aarhus University. 48 pp. - NERI Technical Report no. 770.
Background and objectives
The objective of this assessment is to improve the foundation for decision-making about introduction of a road pricing system that aims to reduce the health impacts and social costs of traffic-related air pollution.
The analysis focuses on how road emissions, air quality, population exposure, and social costs of air pollution depend on geography (different city sizes and rural areas) and time of the day (rush hours versus non-rush hours). A review of Danish studies related to road pricing has also been carried out to assess the expected effect of road pricing on traffic performance (km travelled), vehicle composition and speed that are factors affecting air pollution.
In 2008 the Danish government decided to introduce road pricing based on km-charging combined with reductions in other taxes on vehicles (registration tax and owner tax). The km-based charge will be based on GPS (Global Positioning System). The goal is that road pricing for heavy-duty vehicles should be introduced from 2011 and for passenger cars from 2015 with a gradual introduction for passenger cars. The final decision about when to introduce road pricing has not yet been made.
Results
Expected reductions in traffic
A literature review showed that the impact of road pricing on km travelled depends on the level of the km-based charge and reductions in km travelled of 7-13% may be expected. Road pricing mainly affects passenger cars and has less effect on commercial vehicles (light-duty and heavy-duty vehicles). One study assessed the impact of road pricing targeting congestion. This study showed that morning and afternoon rush hour traffic was reduced by 12% and 5.5%, respectively, with an overall reduction of 7.8%. Some studies only looked into the effect of km charging while others assumed km charging in combination with lowering of e.g. the registration tax on new vehicles. Combinations with a low km charge may actually increase km travelled.
Impacts on air quality
One study has examined the impact on road pricing on air quality levels in Copenhagen. The expected reduction in km travelled was 11.7% and this reduced the number of exceedances of the air quality limit value for NO2 of 40 ?g/m3 in 2010 from 80 to 58 exceedances out of 138 busy streets examined.
To illustrate the impact of congestion charging two scenario examples were calculated for a single busy street in Copenhagen (Jagtvej). In the first scenario it was assumed that km travelled was reduced by 10% as a result of reduction alone in passenger cars with 12.7%. In the second scenario it was assumed that km travelled during morning and afternoon rush hours was reduced by 12% and 5.5%, respectively, achieved with a reduction in passenger cars of 15.6% and 6.4%, respectively. This corresponds to a reduction in km travelled of 7.8%. For both scenarios the reductions in street NO2 concentrations were less than 3%. The reason why the reduction in street concentrations is modest is due to the fact that the emission contribution from passenger cars is relatively small compared to heavy-duty vehicles, and the urban background concentration is also affected by the regional contribution that is unchanged.
Geographic variation in emissions, air quality and population exposure
The analysis of the geographic distribution of road emissions, urban background concentrations, and population exposure showed that they increase with increasing city size. Copenhagen has significantly higher levels compared to other Danish cities. However, there is also a middle group of cities that are similar concerning emissions, population density, air quality and population exposure.
Geographic variation in social costs of air pollution
The social costs of air pollution (excl. CO2) per km travelled has been estimated based on air quality modelling of road emissions from the CEEH project (Centre for Energy, Environment and Health). Calculations are based on the air quality modelling in the EVA-system (Economic Evaluation of Air Pollution). The EVA-system is NERI’s integrated model for estimation of social costs of air pollution. It includes regional as well as local scale air quality modelling. Estimation of health impacts is, among others, based on years lost due to air pollution. The documentation of the method can be found in the NERI Technical report No. 507.
The geographical variation of social costs of traffic-related air pollution is on average modest as the social costs are approx. 0.16-0.22 DDK per km in Copenhagen and approx. 0.08-0.12 DDK per km for the rest of Denmark. The variation of social costs of air pollution is large among the different vehicle categories. The highest social costs are for buses and trucks in Copenhagen (about 1.30 DDK/km) and the least social costs are for diesel-powered passenger cars driving in the country side (0.04 DDK/km). In Table 1 the estimated social costs of air pollution (excl. CO2) are summarised for road traffic per km travelled for different vehicle categories and for different city-country side categories.
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| ||||
DKK/km | Country side
| Smaller cities | Large city (Copenhagen) | |
Passenger cars - petrol - diesel Buses (diesel) Vans (petrol) Vans (diesel) Trucks (diesel)
Weighted average |
0.04 0.04 0.52 0.08 0.08 0.43
0.08 |
0.06 0.10 0.80 0.10 0.17 0.61
0.12 |
0.09 0.25 1.31 0.14 0.41 1.09
0.22 | |
Full report in PDF-format (1,84 MB).
