Assessment of the effectiveness of fuel and toll pricing policies in motorway emissions: An ex-post analysis

In this paper the environmental impacts of fuel and toll pricing policies were evaluated for eight Portuguese motorways for the period between 2008 and 2011. To perform such study, firstly the analysis of the elasticity was done to assess the sensitive of traffic demand. Then emission costs were estimated considering an integrated approach of environmental and human health impacts. Two motorway groups were analyzed: one originally built with both conventional and electronic toll systems (G1); and another recently equipped with non-stop electronic tolls (G2). The results show that the elasticity of the system changes with the fluctuation prices, particularly influenced by toll prices variation. During the analysis period, traffic volumes decreased (8-11% in G1, and 15-41% in G2). About 75% of traffic flow shows a high statistical significance correlation (p < 0.05) with toll prices, which highlight the impact of toll prices. Differences between emission costs can be close to 50% in those motorway groups. Nevertheless, due the absence of data in alternative routes, the obtained results show only the potential maximum environmental gains of these policies in motorways. This limitation is very important in the quantification of the environmental global impacts. Non-toll roads are usually characterized by slower speeds and higher emissions. Therefore the above mentioned gains can be converted, in these cases, in losses.