详情

Design Guidance for Freeway Mainline Ramp Terminals

项目名称：	Design Guidance for Freeway Mainline Ramp Terminals
摘要：	The design values for freeway ramps in the AASHTO Policy on Geometric Design of Highways and Streets (Green Book) rely heavily on research conducted in the late 1930s and early 1940s, predating the development of the Interstate system. The studies relied entirely on passenger cars for acceleration and deceleration rates, without consideration of trucks and busses; this was based on the assumption that the acceleration distances for heavy vehicles would be "entirely out of reason." Vehicle characteristics have changed since the original research. For example, the weight-to-horsepower ratio for trucks in 1965 was 400 lb/hp compared with the currently used ratio of 200 lb/hp. According to the Green Book, the mainline terminal of a ramp is that portion adjacent to the through traveled way, including speed-change lanes and tapers. There are two basic designs for freeway ramp terminals: tapered and parallel. Transportation agencies tend to adopt one of these designs as a standard (often different for entrances and exits), but there is little objective information available for designers on their relative strengths. The objective of this research is to develop improved design guidance for freeway mainline ramp terminals suitable for inclusion in the AASHTO Green Book. As appropriate, the guidance should also address issues related to the design of the gore area and any transitional area to the ramp proper.
状态：	Completed
资金：	70000.00
资助组织：	Federal Highway Administration<==>American Association of State Highway and Transportation Officials (AASHTO)<==>National Cooperative Highway Research Program
项目负责人：	Derr, B Ray
执行机构：	CH2M Hill, Incorporated
开始时间：	20050127
实际结束时间：	20070426
主题领域：	Bridges and other structures；Design；Highways；Operations and Traffic Management