This document provides technical documentation of mobile source activity data collection as a part of the ten volumes of the Emissions Inventory Improvement Program (EIIP) materials. These volumes provide standard procedures for calculating air emissions data with targeted quality objectives using cost effective approaches, but in some cases have become outdated. 

“Volume 4 – Mobile Sources” provides a reference for collection of activity data needed as input to onroad and nonroad mobile models. For onroad mobile sources, the chapters include guidance on developing vehicle registration distributions, mileage accumulation, rates from inspection and maintenance programs, development of fleet characteristics, fuel consumption, and vehicle miles travelled. For nonroad mobile sources, the chapters include approaches for estimating lawn and garden equipment activity.

The mobile source emissions sections in this volume have been replaced by onroad and nonroad mobile model documentation available from the Office of Transportation and Air Quality

• Chapter 1 - Preferred and Alternative Methods for Gathering and Locating Specific Emission Inventory Data (PDF)(124 pp, 348 K, June 1996)
  This volume presents guidance on the use of three specific data sources for use in developing distributions used in the MOBILE emission factor model.
• Chapter 2 - Use of Locality - Specific Transportation Data for the Development of Mobile Source Emission Inventories (PDF)(108 pp, 336 K, September 1996)
  This particular report is to provide guidance for state and local agencies for use in developing motor vehicle emission inventories using Highway Performance Monitoring System (HPMS) datasets and Travel Demand Model (TDM) outputs.
• Chapter 3 - Guidance for Estimating Lawn and Garden Equipment Activity Levels (PDF)(60 pp, 241 K, September 1997)
  This study was to develop methodological guidelines to improve the accuracy of county-level activity estimates from lawn and garden equipment