Using ITS Microwave Vehicle Detection Sensors Instead of Operating 14 Continuous Count Station Sites Was Estimated to Save Michigan DOT $48,959 Per Year.

University Researchers Evaluated Upgrades To Traffic Monitoring Systems in Michigan.

Date Posted

An Evaluation of Michigan’s Continuous Count Station (CCS) Distribution

Summary Information

This project evaluated the accuracy of traffic volume data collected by Intelligent Transportation Systems-Microwave Vehicle Detection System (ITS-MVDS) sites geographically distributed throughout Michigan. Accuracy was compared against the volume, speed, and vehicle classification data collected from Michigan Department of Transportation’s (MDOT) Continuous Count Station (CCS). A cost saving analysis was performed. The project also analyzed site appropriateness and developed recommendations for where sites should be relocated to enhance traffic information, reduce data redundancy, and expand data sampling. Data from 614 ITS-MVDS sites, 54 WIM sensors, and 126 CCS stations was obtained from 2012 to 2016; the study occurred from April 1, 2016 to April 30, 2018.


Firstly, existing CCS sites were evaluated via redundancy and sufficiency analysis. Then both CCS sites and ITS-MVDS sites were analyzed to identify ITS sensors that could replace existing CCS sites or be added into MDOT’s traffic monitoring program. Finally, cost savings were estimated using the proposed Traffic Management Plan (TMP) with a total of 159 sensors. ITS MVDS sensor data for volume, speed, and vehicle classification were evaluated and compared with those from adjacent CCS sites by assuming that the data from CCS sites are ground truth data. Equivalent annual costs (EACs) were used to calculate annual cost savings with an analysis period of 20 years (from 2016), a discount rate of 2.5 percent, and an assumed lifespan of 20 years for CCS stations and 10 years for ITS sensors. It was assumed that ITS sensors would be replaced every 10 years with the first replacement occurring five years after 2016. The proposed TMP involves removing two CCS stations, replacing 12 CCS stations with ITS sensors, and adding 37 ITS sensors.


Cost saving analysis revealed that for the proposed TMP, removing two CCS stations and replacing 12 CCS stations with ITS sensors would result in an estimated cost savings of $48,959. Adding 37 ITS sensors would save an additional $153,031. Over the analysis period of 20 years, the total annual cost saving was $201,990.

Evaluation of the data from the ITS-MVDS sites found that ITS sensors could provide high quality data when they are well maintained. About 35 percent of ITS sensors were found to be accurate, with a Mean Average Percentage Error (MAPE) of less than 10 percent.

Approximately 60 percent of ITS speed data yielded similar speed distributions compared to the data from nearby CCS sites. The average speed of the ITS sensors deviated from CCS speed data by about two to five mi/h, based on 23 directional ITS sites nearby CCS sites. The deviation of the 85th percentile speed value was very low between most of the comparable ITS sites and CCS sites.

ITS sensors successfully classified vehicles into four vehicle types  and had similar accuracy as CCS stations, although ITS sensors tended to underestimate small vehicles.

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