Geometric design of metered on-ramps: state-of-the-practice and remaining challenges

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.

KEYWORDS:

• Metered on-ramp
• queue storage length
• traffic flow arrival profile
• acceleration length
• acceleration characteristics
• ramp metering warrants

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This research was sponsored by the California Department of Transportation (Caltrans), Grant Number 65A0486.