ABSTRACT
Successful operation of ramp-metering needs to provide both an adequate queue storage space and a sufficient acceleration length at a metered on-ramp. This paper reviewed the existing methodologies and practices pertaining to queue storage and acceleration length design at metered on-ramps, and identified challenges that need to be solved during the metered on-ramp geometric design process. It was summarized that the development of metered on-ramp queue storage design guideline needs to consider the impact of on-ramp traffic flow arrival pattern on the actual queue storage needs at various metered on-ramp types. Meanwhile, considering the potential impact of ramp-metering on drivers’ acceleration behavior, it is necessary to develop dedicated acceleration lane length design standards for metered on-ramps based on field collected acceleration performance data. In addition, it is desirable to establish clear ramp geometric warrants to enhance the existing ramp-metering warrants presented in the MUTCD and local ramp meter design guidelines.
Disclosure statement
No potential conflict of interest was reported by the authors.