The environmental impact of road investments: an economical analysis with an emphasis on by pass investments

摘要

When motoring was in its infancy in Sweden the main roads were located straight through towns - the first generation meeting between road and town. When traffic flows were growing, traffic problems along these roads were growing as well. The second generation meeting is when a by pass is built. Winners are heavy traffic, long distance travellers and inner city residents, getting less noise, exhaust fumes and vibrations. But by passes often cause encroachment on recreation areas for nearby residents. The third generation meeting occurs at substantial distances between built-up areas and continuous, broad roads passing towns. In southern Sweden, main roads often are built as such roads, but not in northern Sweden. There traffic flows are too low. "Environmental encroachment" is not yet valued monetarily in the Cost Benefit Analysis (CBA). The missing value includes physical encroachments in areas important for nature, recreation and/or culture, the barrier the road constitutes (towards an attractive area, river, lake etc.), and the impact on urban or rural landscape. Contingent Valuation Method (CVM) can be a suitable valuing encroachment, especially when winners and losers are different groups. Losers can state their willingness to pay (WTP) for getting environmental improvement (for example a road tunnel). Ex post studies are preferable. A road investment resulting in encroachment is usually controversial and respondents in ex ante studies tend to exaggerate their willingness to pay. In an ex post study they have no incentive for acting strategically. The development of a calculation model, from ex post studies with CVM, has been started. It shows that mean annual willingness to pay in a nearby area for getting a motorway that is a barrier between the dwelling and a lake in tunnel is about 4000 SEK (> 400 Euro).