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原文传递 Feasibility of Using a Constant Acceleration Rate for Freeway Entrance Ramp Acceleration Lane Length Design

题名：	Feasibility of Using a Constant Acceleration Rate for Freeway Entrance Ramp Acceleration Lane Length Design
其他题名：	AASHTO.(2011)."A policy on geometric design of highways and streets."Washington,DC.
正文语种：	英文
作者：	Guangchuan Yang
关键词：	Acceleration length;Speed profile;Constant acceleration;Statistical test
摘要：	When estimating the required acceleration length of vehicles accelerating from a stopped position, a constant acceleration rate is sometimes assumed for the sake of simplicity. Nevertheless, to date there is no clear-cut evidence showing whether a constant acceleration rate is reasonable in providing appropriate acceleration lengths. In this paper, the estimation errors associated with the constant acceleration assumption were investigated. For each sample, a piecewise-constant acceleration model was used to figure out the vehicle's speed versus location profile; accordingly, the constant acceleration rate was calculated. Using this constant acceleration rate, speeds at the predetermined locations were calculated and compared to the results that were generated by the piecewise-constant acceleration model. Based on the statistical analysis of 575 individual vehicle-accelerating trajectories, it was found that the constant acceleration model failed to reproduce the field-observed acceleration profile. Therefore, simply using a constant rate cannot accurately estimate the required acceleration lengths at various freeway design speed scenarios. This indicates that when adopting the constant acceleration assumption for each design speed scenario, it is necessary to use an appropriate acceleration rate that fits for this design speed. Finally, this paper revealed that normal acceleration rate ranges from 1.31 m=s～2 (4.3 ft=s～2) at 64 km=h (40 mph) to 1.8 m=s～2 (5.9 ft=s～2) at 32 km=h (20 mph).
出版年：	2018
论文唯一标识：	P-72Y2018V144N03011
英文栏目名称：	TECHNICAL NOTES
doi：	10.1061/JTEPBS.0000122
期刊名称：	Journal of Transportation Engineering
拼音刊名(出版物代码)：	P-72
卷：	144
期：	03
页码：	93-100