Author(s):
D.R. Drew, J.H. Buhr, R.H. Whitson
Publication Date
1968
Abstract
This paper presents a new approach to the determination of the capacity and service volumes in ramp-freeway merging areas. The capacity of a merging area is based on the critical gap concept and on assumptions regarding the distribution of gaps in the freeway shoulder lane. The service volumes suggested are developed from considerations of the ramp junction as a queueing system. A level of service can then be provided such that a ramp vehicle has a certain probability of finding the merging area empty. Another measure of level of service is the delay suffered by ramp vehicles. This aspect is treated and charts presented for its determination. The above merging parameters all involve the critical gap of the junction. This critical gap can be estimated from the geometries of the ramp-freeway junction by a regression equation, developed through the study of a number of entrance facilities, which relates the critical gap to the length of acceleration lane and the angle of convergence, Relationships are also presented of estimating the entire gap acceptance characteristic from these two geometric features. The paper proceeds to discuss in detail the application of the developed merging parameters in freeway design and control.
Report Number:
430-4
Link(s):
Document/Product
http://tti.tamu.edu/documents/TTI-1968-3.pdf
Publication/Product Request
TTI reports and products are available for download at no charge. If an electronic version is not available and no instructions on how to obtain it are given, contact the TTI Library.