AAAR 31st Annual Conference
October 8-12, 2012
Hyatt Regency Minneapolis
Minneapolis, Minnesota, USA
Abstract View
Mobile Monitoring: a Better Tool to Measure Vehicle Emission Factors
SCOTT FRUIN, Neelakshi Hudda, Ralph Delfino, Constantinos Sioutas, University of Southern California
Abstract Number: 245 Working Group: Urban Aerosols
Abstract Tunnel studies and remote sensing can track trends in fleet emissions, important in judging the effectiveness of emissions standards, but these methods are expensive and often do not capture the full range of vehicle operating conditions. A novel, mobile approach was developed that is more cost effective and appears to capture the spread in vehicular emissions during real-world operating conditions, important in capturing the contributions from high emitting vehicles, some of which are only high emitting during certain driving modes. Emissions were directly measured on-road using a mobile monitoring platform. When combined with real time traffic data, distributions of emission factors (EFs) for gasoline powered light-duty (LDV) and diesel powered heavy-duty vehicles (HDV) can be accurately calculated. Fleet average LDV EFs were generally in agreement with most recent studies and an order of magnitude lower than HDV EFs. However, HDV EFs appeared to reflect the continuing decreasing trend in diesel emissions, due to tighter new truck emission standards (e.g., 2007) and recent regulations focused on goods movement in Los Angeles. In particular, the HDV EFs on I-710, the primary route used for goods movement in LA were frequently lower than on other freeways. Therefore, it appears the contributions from higher LDV vehicle miles traveled (VMT) on freeways with lower truck volumes are now beginning to erode the traditional dominance of higher truck volumes in producing the highest total freeway emissions. This finding provides further evidence of the importance in reducing the rates of LDV VMT growth for urban air quality, despite the relatively low emissions per mile now achieved by LDVs.