Selecting Road-Noise Abatement Measures: Economic Analysis of Different Policy Objectives

To satisfy new legislation, the Norwegian Public Roads Administration implemented a national façade insulation program encompassing 2,500 dwellings exposed to high levels of road traffic noise. Thereby, the road owner brought the equivalent noise levels from road traffic in compliance with a new indoor limit of 42dB. Cost-effectiveness analyses show that façade insulation was the least expensive noise-control alternative per dwelling. However, cost-benefit analyses show that the benefits were less than 20 per cent of costs. One reason for the poor benefit-cost ratio is that only the residents of the targeted dwellings benefit from at-receiver measures. Measures at the source and/or targeting the propagation paths also provide noise benefits for residents living along the same streets as the most noise exposed and inadequately insulated dwellings. A mixed noise abatement policy employing low-noise asphalts in addition to façade insulation is therefore considered. For 750 dwellings where two or more of the dwellings were located along the same road stretch, low noise asphalts replaced façade insulation as noise abatement method. Façade insulation was kept as noise abatement method for the remaining 1,750 dwellings. The mixed noise abatement policy costs more, but now provides total benefits that match the total costs. Even higher benefit-cost ratios are obtained when reframing the economic analyses within the context of a national policy to reduce noise annoyance, and when focussing solely on more densely populated areas where lownoise asphalts is a viable alternative to façade insulation. Since environmental authorities are in the process of further lowering the indoor noise limit, the road authorities should consider preparing an organisational and financial framework for implementing low-noise surfaces based on cost-benefit calculations. Such a policy would have the added benefit of improving urban soundscapes for a significant number of residents, workers, cyclists, pedestrians and children.