Assessing the impact of bus technology on greenhouse gas emissions along a major corridor: A lifecycle analysis Sabrina Chan, Luis F. Miranda-Moreno, Ahsan Alam, Marianne Hatzopoulou ⇑ Department of Civil Engineering and Applied Mechanics, McGill University, Macdonald Engineering Building, Rm. 492, 817 Sherbrooke Street West, Montreal, Quebec, Canada H3A 2K6 article info Keywords: Transit emissions Alternative fuels Emission modeling Lifecycle analysis abstract This paper evaluates the impact of alternative bus transit technologies including com- pressed natural gas, biodiesel, and diesel-electric hybrid on greenhouse gas emissions along a busy transit corridor using a lifecycle analysis approach. In addition, we compare the operational emissions of buses running on these technologies using an instantaneous speed and an average speed model. Our results indicate that operational emissions make-up the largest portion of lifecycle emissions. When comparing instantaneous and average speed emissions we find that both methods produce consistent results for diesel, however, the average speed method underestimates biodiesel emissions by 21% and over- estimates compressed natural gas emissions by 16%. Bus technologies ranked in increasing order of lifecycle greenhouse gas emissions are: hybrid, compressed natural gas, biodiesel, and conventional diesel. Ó 2013 Elsevier Ltd. All rights reserved. 1. Introduction With increasing investments in transit systems across metropolitan areas in North America, most transit agencies have placed emphasis on reducing their carbon footprint. This is often done through operational improvements, such as transit signal priority or jumper lanes, which help reduce idling times therefore reducing greenhouse gas (GHG) emissions and alternative technologies. Lifecycle analyses (LCA) that have investigated natural gas generally demonstrate that buses run- ning on it provide modest or no reductions compared to conventional diesel buses (Karman, 2006). Further reductions have been observed using bio-CNG (Ryan and Caulfield, 2010). Bioethanol from wheat and corn show 6–21% higher GHG emis- sions than conventional diesel while ethanol derived from cassava and sugarcane demonstrate reductions of 16–44%; bio- diesel produced from rapeseed and soybean offers substantially lower lifecycle GHG emissions (Yan and Crookes, 2009). LCA for hydrogen buses show that under current hydrogen production technologies, hydrogen buses generate slightly more GHG emissions than diesel buses (Frey et al., 2007). Despite the availability of studies that have evaluated the impacts of bus transit technologies, there is a general lack of research on specific transit corridors whereby local road characteristics and detailed bus drive-cycles are taken into account. Most existing LCA studies use generic emission factors to derive operational-level emissions ignoring the particular charac- teristics of the corridor to be evaluated. Our study, set in Canada, focuses on a busy bus transit corridor. Our objectives in- clude (1) evaluating the impact of alternative bus transit technologies including compressed natural gas (CNG), biodiesel, and diesel-electric hybrid on GHG emissions using a LCA approach, and (2) comparing the operational emissions of buses 1361-9209/$ - see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.trd.2013.01.004 ⇑ Corresponding author. Tel.: +1 514 398 6935; fax: +1 514 398 7361. E-mail address: marianne.hatzopoulou@mcgill.ca (M. Hatzopoulou). Transportation Research Part D 20 (2013) 7–11 Contents lists available at SciVerse ScienceDirect Transportation Research Part D journal homepage: www.elsevier.com/locate/trd