Quantification of the Emissions from Personal Mobility. Estimation Based on General Mobility Surveys
Nominated for The Planning for Sustainable Land Use and Transport Award
Manel Pons, Institut D'Estudis Regionals I Metropolitans De Barcelona (IERMB), Elena Domene, Institut D'Estudis Regionals I Metropolitans De Barcelona (IERMB), Marta Garcia, Institut D'Estudis Regionals I Metropolitans De Barcelona (IERMB)
The combination between surveys and estimation models has been a research tool that has made possible to quantify and infer the personal transport emissions. The results show a significant influence of urban form factors in transport emissions.
Mobility surveys are statistical instruments which allow obtaining information on how and why the population travels. They represent a tool for the analysis of the main mobility patterns, thus enabling transport planning. In this study, we present the outputs of a collaboration between the institutions IERMB and MCRIT, in which information from regional mobility surveys on individuals' travel patterns has been combined with information from a traffic model that estimates the journey's associated emissions. Ultimately, the emissions of the journeys made by one individual can be added up, thus providing us with an approximation of the travel footprint of such person. The results we believe are of great relevance for policy formulation.
The traffic model used is the SIMCAT model (Modelling and Information System for Regional Policy Evaluation in Catalonia). The SIMCAT is an advanced system that estimates transport flows and journeys made disaggregated by transport mode through the modelling of the stages of journeys generation, their spatial distribution and the modal split. On the basis of transport flows, and applying models for the calculation of energy consumption and associated emissions, the SIMCAT estimates the emissions of primary pollutants CO2, NO2, NOx and PM10 generated by transport in Catalonia, among other indicators of environmental impact. The SIMCAT has been used since 2002 to assess the transport infrastructure plans in Catalonia.
This methodology has been applied to two very specific regional mobility surveys, namely the Survey of Everyday Mobility of Catalonia 2006 (EMQ 2006) and the Metropolitan Transport Database 2011/13 (BBDDMM 2011/13), which involves data collected in 2011 and 2013. The questionnaires of the two surveys are comparable, and the interviews were held, in both cases, following computer-assisted telephone interviewing (CATI). The information collected refers to the journeys made the day before the interview and includes information on origin-destination, transport mode used, and duration of the journey, as well as some personal information about the interviewee and the reason for using her main mode of transport. Emissions were only estimated for the journeys made within the Barcelona Metropolitan Region by individuals of 16 years or more.
The results show a significant influence of urban form factors in transport emissions. In particular, population travelling from and to low-density urban areas make a greater use of the private vehicle (the car) and generates more emissions than those who travel within high-density urban areas. Furthermore, the temporality of the selected surveys is also important. The EMQ 2006 captures mobility at a time of maximum economic expansion and employment in Catalonia, whereas the BBDDMM 2011/13 was carried out during the toughest years of economic recession when unemployment rates reached a maximum. The results show that emissions in expansive economic cycles are significantly higher than in the period of recession, thus supporting the hypothesis of transport as a derived demand.
All in all, we believe in the potential of the methodology to estimate the emissions of personal mobility and analyse their relationship with urban form and socioeconomic variables, which makes it a valid research tool to inform the design of policies aimed at reducing the environmental impact of mobility.
Association for European Transport