Procedures to Determine Frontage Road Level of Service and Ramp Spacing (1393-4F)

The main objectives of this study were to develop procedures for estimating the level of service on freeway frontage roads and to determine desirable spacings for ramp junctions. The tasks involved developing 1) procedures for analyzing frontage road weaving sections, 2) recommended spacing requirements for ramp junctions, and 3) a technique to evaluate overall operations on a continuous frontage road section. The two weavmg segments analyzed included a one-sided weaving area formed by an exit ramp followed by an entrance ramp and connected by an auxiliary lane and a two-sided weaving area formed by an exit ramp followed by a downstream signalized intersection. Spacing guidelines were developed for the following frontage road sections: exit ramp to entrance ramp; exit ramp to downstream signalized intersection; and signalized intersection to metered entrance ramp. The technique to analyze overall frontage road operations can be used to estimate the level of service for a frontage road section several kilometers in length.