Gap metering for active traffic control at freeway merging sections

Peter J. Jin, Jie Fang, Xiaowen Jiang, Michael DeGaspari, C. Michael Walton

Research output: Contribution to journalArticlepeer-review

5 Scopus citations


Freeway merging sections are critical segments that can recurrently activate peak-hour traffic congestion. This article proposes a novel vehicular gap control method as a new Active Traffic Management (ATM) strategy to be added to the existing Intelligent Transportation System (ITS) toolboxes for freeway merge control. The proposed strategy, “Gap Metering,” can be considered a non-stopping mainline version of ramp metering. It utilizes signals advising mainline through vehicles to yield sufficient gaps for merging vehicles. Detailed system design and control methods are proposed and implemented in VISSIM (please spell out the abbreviation of VISSIM for this first instance), a microsimulation software package. Different driver behavior sets with different standstill headway values are created to allow switching between gap-metered vehicles and regular vehicles. We evaluate the proposed system through two VISSIM models built and calibrated, respectively, for both the I-894 corridor in Milwaukee, WI, and the Riverside Drive segment on I-35 northbound in Austin, TX. Both corridors experience severe morning peak-hour congestion. We use the I-894 corridor for testing the system design parameters and use the I-35 corridor to conduct a comparison with the ramp metering strategies. The I-894 results indicate an average of 10–20% network delay reduction among all scenarios. We then tested the scenario on the I-35 corridor and compared with the ALINEAR ramp metering. Gap metering strategies alone or combined with ramp metering can, respectively, reduce 17% and 27% more total delay than ramp metering only control at 20% compliance rate.

Original languageEnglish (US)
Pages (from-to)1-11
Number of pages11
JournalJournal of Intelligent Transportation Systems: Technology, Planning, and Operations
Issue number1
StatePublished - Jan 2 2017

All Science Journal Classification (ASJC) codes

  • Software
  • Control and Systems Engineering
  • Information Systems
  • Automotive Engineering
  • Aerospace Engineering
  • Computer Science Applications
  • Applied Mathematics


  • active traffic management
  • gap metering
  • merging control
  • ramp control
  • ramp metering


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