A multiscale assessment on negative transport externalities: Magnitude, composition and policy implications

While transportation supports mobility, economy and wellbeing, there is a wide range of negative transport externalities. This paper reviews and examines eight major negative transport externalities from direct greenhouse gas emissions, air pollution, well-to-tank emissions, traffic noise, habitat change, traffic congestion, traffic fatalities and casualties to barrier effects. The study provides an updated assessment of these eight negative transport externalities in 2020 by applying a consistent methodology in both passenger and freight transport at different spatial scales. Detailed audits of EU-28, Australia and Hong Kong are conducted to estimate the magnitude and composition of negative transport externalities at the regional, national and city levels, respectively. Our findings suggest that the total negative transport externalities accounted for 2.7-5.7% of Gross Domestic Product (GDP) and trucks contributed to at least 25% of total externalities. At the city scale, the social impacts on human health are notable. More proactive and timely policies that cover both passenger and freight transport are necessary to achieve sustainability in the transport sector.