Ecological compensation of the impacts of a road. Preliminary method for the A50 road link (Eindhoven-Oss, The Netherlands)

After years of efforts to avoid or reduce the impact of infrastructure projects on nature, the principle of ecological compensation has been incorporated in Dutch governmental policy. Ecological compensation aims to recover those ecological functions and natural values that still remain affected after maximum effort has been made to reduce the impact of the intervention (mitigation). The accepted aim of current policy is thus no-net-loss of area and quality by means of mitigative and compensatory measures. As part sf the planning process for construction of a stretch of road in The Netherlands, viz,, the A50 road link in the province of North Brabant, a Nature Compensation Plan (NCP) was required to be drawn up. This work has recently been completed by the Regional Directorate of Public Works and Water Management, the initiator of the intervention. The NCP, initially presented as a Draft Plan, was drawn up by the Regional Directorate using a preliminary method designed by the Centre of Environmental Science of Leiden University for deriving compensatory measures. After an opportunity for public comment, the Draft Plan was revised to form a Final NCP. This article describes, firstly, the preliminary method for deriving ecological compensatory measures. The method starts by quantifying the effects of habitat loss, habitat disturbance (by changes in noise emissions, in the water table and in outdoor recreational patterns), barrier action and fauna casualties. Following mitigation of impacts on nature, compensation for non-mitigable effects focuses successively on area size, derived from the impact on breeding birds, and on area quality, derived from the habitat requirements of the vegetation and fauna groups affected by the road. Guidelines for identifying appropriate locations for compensation are also formulated. Secondly, the compensation method is applied to calculate the mitigative and compensatory measures for the A50 trajectory between Eindhoven and Oss. Thirdly, two comparisons are made: the Draft NCP is compared with the results of the preliminary method, and the Draft and the Final NCP are compared with one another in order to identify the role of the interest groups that played a major role in commenting on the Draft Plan. Finally, realization of the compensatory measures and development of the preliminary method itself are discussed. On the basis of the experience with the A50 case study, a more robust compensation method for road projects is to be developed.