The Michigan Department of Transportation (MDOT)’s strategic plan for Intelligent Transportation Systems (ITS) revolves around attaining and demonstrating key mobility, safety, productivity, energy and environment, and customer satisfaction benefits at a reasonable and sustainable level of investment. The research team was tasked with evaluating the return on investment of the newest major ITS construction projects, which have introduced a large number of new applications and devices. The evaluation was based on data from the different traffic operations centers (TOCs), surveying the public, and analysis with statistical modeling, microsimulation, and a tiered cost-benefit analysis.
The objective of corridor microsimulation was to quantify detailed benefits resulting from MDOT ITS deployments (DMS, CCTV, detectors, travel time signs, TOCs). In this project, the research team selected a sample of seven representative corridors (2-3 from each TOC) across Michigan. Corridors were chosen based on AADT, ITS device density, economic impact, and crash/incident history, with the objective of choosing corridors whose results could be transferable statewide. The Quadstone Paramics traffic microsimulation software package compared "with/without" ITS scenarios to quantify benefits. DMS, CCTV, and MVDS are the devices evaluated in the simulations, they are investigated with regards to their effect to induce short-term, near-incident alternate route diversion.
The simulation study provided insight into the operational performance of ITS at the corridor level. The analysis found that ITS is most beneficial in high duration, high reduction scenarios. Many factors, including traffic volume, network configuration, and ITS device placement, influenced the results. Given the complexity of the analysis and the random nature of incident occurrence, the results of this study should be viewed as a limited, but representative sample of ITS performance on the corridor-level in Michigan.
In an effort to determine incident reduction as a result of ITS, a descriptive statistical incident duration analysis was performed based on processed data provided by the TOCs. Finally, incident delay analysis as affected by ITS was performed.
The most notable effect of ITS observed in reducing incident duration occurred in the Statewide TOC region, which saw a 35.7 minute assisted incident reduction as a result of ITS. For LCAR (lane closure and reduction) incidents, the reduction was more substantial at 44.9 minutes for all ITS and 57.7 minutes for CCTVs. Additionally, in the defined STOC ITS Regions One and Two, average LCAR incident duration is reduced by 49.5 minutes and 67.2 minutes, respectively, with the largest benefit occurring with regard to incidents blocking either one lane or all lanes. Through incident delay analysis, it was determined that ITS can reduce average incident delay by 8.2%, from 0.61 to 0.56 minutes per vehicle.
Cross-sectional statistical analysis determined that ITS reduced incident durations between 18.9 and 24.5 minutes for high-impact incidents and between 24.5 and 35.7 minutes for FCP assisted events.
When the incident delay savings from ITS deployments were calculated for the 65,360 incidents in the study period, the monetized benefits totalled $26.3 million.
Secondary incidents are considered to be intrinsically related to the duration of an incident. This study assumed 20% of observed incidents managed by TOC staff are secondary incidents. Reducing initial incident duration is expected to reduce the number of secondary incidents. The following table summarizes the results of the calculations the study team performed.
|Number of secondary incidents|
|Number of secondary incidents avoided|
|Secondary incident delay saved (hours)|
|Secondary incident delay saved ($)|
Simulations of CO2 and NOx emissions with and without ITS deployments in Michigan were performed using the Paramics CMEM API plug-in. This program calculates cumulative emissions during a simulation period. The total emissions reduction is calculated by subtracting the emissions of the scenario with ITS from the scenario without ITS.
Total emissions benefits from ITS tend to be highest at higher incident duration scenarios, regardless of duration reduction. In this study, the benefits were estimated to total $1,803,853.
The Paramics CMEM API Plug-in generates cumulative network wide total vehicle fuel consumption during the entirety of the simulation period. The fuel consumption saved as result of incident duration reduction and ITS-influenced detour were calculated in a similar manner as delay and emissions, as explained earlier.
The fuel consumption benefit is highest in high duration, high reduction scenarios, similar to other study benefits. In this study, the benefits were estimated to total $1,705,897.
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