Health Assessment and Environmental Impacts of Modal Shift in Transportation

Truck transport now accounts for more than half of goods distribution in Japan. However, truck transportation contributes to human health problems and climate change. A modal shift in transportation affects a wide range of factors, including the use of fossil fuel energy, globe-warming, and sea or land resources. The modal shift from truck transportation to sea transportation maybe one method for addressing these problems. The present paper proposes a method for evaluating the influence of the modal shift in transportation on health changes using the technique of health risk assessment. First, the level of airborne carcinogens from ship and truck exhaust was determined. Then, the density of each carcinogen in locations across Japan was calculated. Finally, the number of people in Japan who would suffer from cancer was derived, and the effects of the modal shift on health are evaluated based on the density calculation data and cancer risk. The current study also evaluates the modal shift from truck and car transportation to sea transportation for two representative routes in Japan using the ecological footprint method. Carbon dioxide (CO₂) and other greenhouse gas emissions, and changes in forest cover before and after the modal shift are calculated to show an ecological footprint calculation related to the modal shift in transportation. Based on these assessments, this article confirms that: there is substantial potential for reducing the ecological footprint using the modal shift; and the exhaust emitted by ships poses less harm to people than truck exhaust.