Vehicle Spacing for the Design of Metered On-Ramps

You are here: Homepage > Search

Vehicle Spacing for the Design of Metered On-Ramps

G. K. J. Tom / H. K. Fong

Video data were obtained at seven on-ramp locations during peak periods while ramp meters were operating. There was not much difference in the average vehicle spacing for ramp rates ranging from 240 to 720 vehicles per hour for the lanes where data was obtained. The average vehicle spacing near the ramp meters for these ramp rates was approximately 28.9 feet per vehicle. It is possible that the average vehicle spacing may be different near the end of the queue. The average vehicle spacing near the ramp meter for the seven locations was approximately 28.9 feet per vehicle. At one location the average vehicle spacing was unusually high (35.0 feet per vehicle). This may be related to the vertical alignment of the on-ramp which is on a long, substantial downgrade. It is recommended that a vehicle spacing of 29 feet per vehicle be used for designing storage on metered on-ramps. Additional spacing should be provided for metered on-ramps on long, substantial downgrades. Additional spacing should also be provided for locations where there are significant percentages of trucks, buses, or recreational vehicles.