Abstract
In recent years thousands of miles of freeway-type highways have been constructed to provide for the safe, convenient and effi- cient transportation of persons and goods. Access to thees fa- cilities is provided by on-ramps designed to merge ramp traffic into the high-speed, high-volume traffic stream. The efficiency of traffic movement on freeways and the extent to which the po- tential capacity of freeways can be realised depends in part on the adequacy of the access facilities. Improperly designed en- trances limit the volume of traffic that can use an expressway and generate congestion that often extends back onto the local system.