Maryland DOT’s I-270 Innovative Congestion Management Project Resulted in Travel Time Savings of up to 17 Percent.
Study Implemented Ramp Metering, Active Traffic Management, and Discrete Geometric Improvements to Reduce Traffic Times and Improve Safety.
Maryland, United States
I-270 Innovative Congestion Management (ICM) Ramp Metering
Summary Information
Ramp metering is a freeway operational strategy that regulates the rate at which vehicles enter a highway to reduce traffic congestion. In 2016, the Maryland DOT allocated $100,000,000 to mitigate recurring congestion on I-270, a critical 30-mile interstate from I-70 in Frederick, MD to I-495 in Washington, DC, dubbed the I-270 Innovative Congestion Management (ICM) project. Transportation systems management and operations (TSMO) active traffic management (ATM) strategies were implemented with the real-world deployment of ramp metering in September of 2021.
METHODOLOGY
A high-level analysis of freeway segments on the highway resulted in the development of 14 roadway improvements to address bottlenecks. Microsimulation of adaptive ramp metering was conducted to provide insight into further travel time reduction. Following the microsimulation analysis, 55 ramps were provided with sensors, whose data then led to the development of ramp metering signal timing plans. A before-and-after congestion scan comparison was conducted for the following four time periods in September 2021:
- 2021 ICM geometric improvements with ramp metering
- 2021 ICM geometric improvements before ramp metering
- 2019 - some ICM geometric improvements before ramp metering
- 2017 before any ICM geometric improvements
FINDINGS
- Savings of up to 31 minutes resulted from geometric roadway improvements and ramp metering for I-270 mainline southbound from MD 80 (Urbana) to I-495 (Bethesda) during peak hours.
- Comparisons of data from October 2017, 2019, and 2021 showed travel time savings of up to 17 percent, with a 13 percent in travel time saving came from ramp metering directly.
- For the I-270 southbound local lanes between MD 124 (Gaithersburg) and the Y Split (access to I-495 in Bethesda), ICM improvements and ramp metering deployment resulted in travel time savings of up to 13 minutes.
