Merging from an Acceleration Lane

A model is presented for merging from an acceleration lane of finite length. It is assumed that a car in the acceleration lane travels at speed v while the traffic on the main road travels at speed V > v . A merging car reaching the end of the lane stops instantaneously. The gap acceptance function is assumed to be a step function and the distribution of headways is negative exponential. An expression for the expected delay is given. The calculations suggest that the expected delay does not depend strongly on the length of the acceleration lane, and that most of the merging occurs near the beginning of the lane. Increasing the length of the lane beyond some necessary length, say 600 ft, results in relatively little further benefit in merging.