Limited priority merge at unsignalized intersections

The development of a new gap acceptance model based on limited priority for the major stream is discussed. Field observations were carried out to iden tify the mechanism of the merging process taking place at unsignalized inte rsections under congested conditions. It was found that the major stream he adways were increased due to the merging vehicles, particularly at high flo ws. A limited priority system is proposed based on the assumption that the major stream vehicles would be slightly delayed to accommodate the minor st ream vehicles. Equations for capacity in the limited priority system are pr esented assuming the major stream vehicles to have a bunched exponential he adway distribution and the minor stream drivers to be both consistent and h omogeneous. The gap acceptance model based on the limited priority was then applied to the performance of roundabouts. It was found that the limited p riority merge can have a significant effect on the entry capacity at two-la ne roundabouts. A near linear relationship between the entry capacity and t he circulating stream flow at two-lane roundabouts was identified which was similar to the empirical results from the UK. (C) 1999 Elsevier Science Lt d. All rights reserved.