A guide is presented which is designed to aid transportation professionals and state air pollution control agencies in selecting transportation controls suggested in the regulations pursuant to the Clean Air Act of 1970. Actions considered here emphasize the reduction of traffic volume and congestion and can be implemented within five years. The guide outlines the laws and regulations that require assessment of the air pollution impact of transportation. It then discusses the following techniques for improving traffic flow: freeways, arterials, and downtown distribution. Also discussed are techniques for reducing the concentration of pollution and for reducing auto traffic.