Review of Procedures for Estimating On-Road Mobile Source Emissions Inventoriesfor 1990 Base Year SIPS

摘要

In response to the 1990 Clean Air Act Amendments (CAAA), areas designated asbeing in violation of the National Ambient Air Quality Standards (NAAQS) were required to submit State Implementation Plans (SIPs) beginning with 1990 Base Year Emissions Inventories. In an effort to support the successful implementation of the CAAA and to provide support to state and local agencies responsible for preparing the On-Road Mobile Source sections of the emission inventories, the Federal Highway Administration (FHWA) is seeking to provide information on the emissions inventory development processes that are being adopted by metropolitan areas throughout the country. This document examines the current practices employed by state environmental and transportation agencies, regional transportation committees, and metropolitan planning organizations in developing on-road mobile emissions inventories in 33 designated nonattainment areas. The review focuses on the following areas which are critical to estimating on-road mobile emissions: vehicle miles of travel estimation methodology, speed estimation methodology, development of vehicle fleet and travel fractions, trip length, and operating mode fractions. The study also looks at innovative practices in use around the country.