Valuation of Environmental Impacts of Transport Projects

Notable progress has been made in valuing some benefits of transport projects, such as traveltime savings, but we are struggling to identify monetary values at the individual project level for many environmental attributes, such as changes in open space, noise, air quality, greenhouse gas emissions, and amenity. The difficulty may be aligned to the idea of attribute proximity to the self-interest paradigm. The empirical findings presented here, based on stated-choice experiments, suggest that environmental attributes that are distant in self-interest proximity, such as open space, are unlikely to be appropriately valued when mixed in a trade-off with attributes close in self-interest proximity, such as travel time or reductions in local traffic, unless noticeable gains in self-interest attributes accompany desirable levels of attributes defining environmental impacts. This finding has important implications for the design of empirical studies using statedchoice methods for valuation.