Spatial and territorial developments for life cycle assessment applied to urban mobility—case study on Lyon area in France

Abstract

Purpose The environmental assessment of urban mobility, defined as the movement of people in an urban area, exceeds the scope of transportation life cycle assessment (LCA) with spatial, territorial and even social considerations. The objective of this study is to develop an original interdisciplinary method based on LCA coupled with a land use and transport interaction (LUTI) model to better consider spatial and territorial dimensions in an environmental assessment of urban mobility. Methods Spatial and territorial issues emerge in all LCA stages for urban mobility, and this study illustrates them with an application on the Lyon urban area. To consider most individual daily trips, the geographical boundary is related to the area of influence of the city and the functional boundary includes all transportation modes, with motorized, public and non-motorized transports. The life cycle inventories (LCIs) combined EcoInvent 3.2 inventories with a specific LUTI model, named SIMBAD, local mobility surveys and an emissions and consumptions model (COPERT5). These refinements allow a spatial environmental impacts assessment of urban mobility, expressed per inhabitant per day, at different residential locations and open opportunities to develop precise assessment methods for local air pollutants with detailed description on both population and pollution concentrations. Results and discussion At territorial scale, this study highlights the major contribution to environmental impacts from private cars (around 90%) and the relevance to consider fuel, vehicle, and infrastructure life cycles in a mobility assessment. Spatial interpretations show important variability in function of residential locations and urban form characteristics related to different mobility behaviours, distance travelled and transport technologies used. Through the proposed assessment method for local air pollution impacts on human health, hotspots are revealed in the urban area, especially in the urban centre or along main road axes. In order to test our methodology and open discussions on mobility solutions, two contrasted scenarios are explored on compact city and vehicle electrification both presenting impact transfers between global indicators or with the air pollution exposure indicator. Conclusions Urban mobility and its related environmental burden are not only related to technological choices but are also related to spatial characteristics and territorial context. The combination of urban and spatial tools and data, such as LUTI model, with the LCA methodology improves the local representativeness of environmental assessment of mobility and enlarges the ranges of analysis and perspective. Nonetheless, improvements remain to be made in relation to ongoing developments on spatialized and territorial LCA.