Study Evaluated Effectiveness of Three Applications and Potential Benefits in Managed Lane Operational Strategies on I-66 in Northern Virginia.
Virginia, United States
Developing Analysis, Modeling, and Simulation Tools for Connected and Automated Vehicle Applications: A Case Study for I-66 in Virginia
Summary Information
A simulation-based study analyzed the effectiveness of connected and automated vehicles (CAVs) in mitigating traffic congestion and improving the efficiency of existing lanes on Interstate 66 (I-66) in Northern Virginia. Simulations were conducted in the Federal Highway Administration’s (FHWA) Saxton Transportation Operations Lab. Researchers evaluated SAE J3016 Level 1 automation (driver assistance) technology and three CAV applications: cooperative adaptive cruise control (CACC), speed harmonization, and cooperative merge. Researchers also studied how CAV deployment improved transportation system performance, strategies for incorporating CAV infrastructure, and the benefits of managed lanes (MLs) for connected vehicles (CVs) and CAVs.
Methodology
Researchers conducted a case study based on a 13-mile segment of I-66, between the I–495 interchange and US 29 interchange. Speed and volume data, on- and off-ramp traffic volume data, and travel-time data were collected from November 9 to November 13, 2015. These datasets were used to quantify traffic conditions along the corridor. Traffic simulation software utilizing origin-destination (OD) matrices was used to quantify travel demand. A total of 1,100 simulations were conducted, and researchers conducted four analyses. The first analysis studied CACC highway capacities at five different CAV market penetration levels (0, 25, 50, 75, and 100 percent); capacity was tested along a 7-mi-long freeway segment with four lanes. The second analysis studied the three CAV applications independently, and the third analysis studied bundled CAV applications. The fourth analysis evaluated three ML scenarios, including 1) dedicated ramps and CV- and CAV-eligible HOV lanes, 2) CV- and CAV-eligible HOV lanes, and 3) HOV lanes (baseline).
Findings
- The I-66 simulation study showed that the bundled CAV applications can handle 130 percent of traffic demand without congestion when CAV market penetration is high.
- For all scenarios, individual and bundled CAV applications can improve traffic performance in terms of delay and throughput. Among the three CAV applications tested, CACC platoons were found to be the most effective strategy for maximizing the efficiency of existing facilities and stabilizing corridor traffic flow. The effect of CACC continued to increase as the market penetration rate increased. At market penetration rates of 25, 50, 75, and 100 percent, capacity increased by 14.0, 25.9, 48.0, and 81.2 percent, respectively.
- Bundling CACC and speed harmonization can improve traffic performance further than by applying only them individually. Bundling CACC and speed harmonization can help increase throughput by 0.5 to 15.4 percent and reduce delay by 5.5 to 100 percent.
- Bundling CACC, speed harmonization and cooperative merge applications can improve traffic performance more than CACC and speed harmonization combined when CAV market penetration is less than 50 percent. Under low CAV market penetration conditions, the mainline is not as congested and there are more qualified gaps for on-ramp vehicles to use.
- The study findings indicate that the dedicated ramps and CV- and CAV-eligible HOV lane operational strategies were beneficial, even during early deployment stages. For high CAV market penetration cases, the three ML scenarios had similar performance using bundled CAV applications.
