Incidence of Malfunctions and Tampering in Heavy-Duty Diesel Vehicles

摘要

Emissions from on-road heavy-duty diesel (HDD) vehicles represent a disproportionate source of oxides of nitrogen (NO-x) and particulate matter (PM). Malfunctions and tampering are important causes of elevated emissions and the incidence rates for nineteen categories are listed in the EMFAC 2000 model. However, the estimates for the incidence rates vary by more than 100% depending on the source of the estimate. In addition, the data are old and incomplete. This report details the work conducted under Phase 1 of this project, which was to compare the existing factors for tampering and malfunctioning for HDD trucks in the EMFAC model with those arrived at by the use of several new and independent methods and review of about 7,000 HDD truck records. The approach or design of the new methods followed the life cycle and repair records of a HDD truck. For about 25% or 290,000 miles of its life cycle, the trucks are covered by a warranty and records are kept at ARB and EPA for specific causes of high emissions.