In 1998 INFRAS on behalf of ASTRA, a study on the costs of congestion in road transport carried out (DIMAS 1998). There, the cost of traffic jams on the road were estimated at about 750 million to 1.2 billion CHF per year. The main part relates to time costs, the next relevant category, the accident cost and energy costs are lower than the time cost, and environmental costs are somewhat less important.
The congestion costs correspond to an amount of 0.2 to 0.4% of gross domestic product. Compared to foreign data where values are mentioned up to 2% of the GDP, these values were significantly lower.
The present study thematically deals with similar issues as its predecessor, albeit with changed objectives. In the present study, the following intentions are:
- As part of the update the external costs of road traffic for the year 2000 play an important - though specific - role and should therefore be quantified (including 2005).
- In the transport costs account for the year 2003 (SFS 2006d) congestion costs are not included. The present study closes this gap.
- The storage costs in passenger and freight traffic shall be lowered. The present study provides a basis for this.
- A key objective was to ensure continuity with the results from the previous study.
Because the main goal of this study is an update of the study carried out in 1998, it is methodologically similar as much as possible to ensure continuity.
The phenomena "congestion" appears when transport demand surpasses capacity at one particular point of the road network. Vehicles start obstructing each other and slowing down: Delays occur. In order to quantify these delays, a congestion threshold (velocity) is determined. One talks about congestion only when the velocity drops below this threshold. In this study velocities below 30 km/h count as stop and go traffic and those below 10 km/h as congestion. In order to determine the cost the extent of the congestion (number of involved vehicles) as well as its length are of interest. Therefore, the calculations aim at vehicle hours (number of vehicles multiplied by congestion time). The study responds primarily to the question of the affectedness of inefficiencies in the transport system due to congestion. It only marginally touches the question of cause or causers.
Congestion costs can be differentiated by time loss, raised operating costs, accident costs and environmental costs all due to congestion. Congestion costs represent a special form of external costs: they may be external from the point of view of the road users - the delays are forced on them by the other users - but not from the point of view of the total transport system. They are therefore not borne by the general public. That is how they differ from classic externalities.
Similar to the previous study (ASTRA 1998) different data sources were investigated. Because the data sources differ quite strongly regarding type of survey and content, the calculation approaches had to be adapted to the relevant basic principles. Emphasis was given to the fact that the consistency to the previous study could be adhered to as much as possible.
Here are some of the project conclusions:
The higher shares of leisure traffic (with lower rates) leads to the fact that congestion costs have increased only by 30% even though there were roughly 50% higher time losses in the year 2005 compared to 1995.
The differentiation by vehicle categories (passenger cars, vans, lorries) shows an increase on the part of freight transport. In the year 2000 about 140 million CHF account for lorry transport, in the year 2005 it is about 230 million CHF.