In Denmark scarce resources due to economic constraints had an impact on the road budget. The trend is towards a more narrow-sighted use of investments. This trend, together with an enhanced consideration of environmental impacts, is one of the influencing factors in road investment planning. Against this background a new priority model was developed in 1978-81 concentrating on two main themes as indicated below. Combined they make up the present Danish assessment procedure: (a) estimation, i.e. description and measurement of impacts of each road project under examination. (B) evaluation, i.e. weighing together the different aspects in order to establish priority for the different road projects. Every second year, some projects are selected in accordance with the current budget restrictions. Regarding environmental impacts the elements taken into consideration in the model are noise, barriers and risk perception, and air pollution. In addition the traditional economic components such as journey length, journey time, accidents are taken into account in the model. The road projects typically consist of major or minor by-pass roads, but also of improvements to existing roads and construction of new roads. The 1981 priority for instance comprised 48 projects from which a small number was selected as the best ones and redrawn from the pool to be constructed. The relatively large amount of projects to be assessed has influenced the development of the priority model in the following way. First a quantitative approach had to be taken to estimate the environmental impacts and secondly, due to data restrictions simplistic models had to be used. Especially emphasized should be the uncertainty in parameter estimation together with shadow prices and their dependence on value structures. For the covering abstract of the proceedings see IRRD 274491.
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