Evaluation of a Collision Avoidance and Mitigation System (CAMS) on Winter Maintenance Trucks

Zockaie, Ali; Saedi, Ramin; Gates, Timothy J.; Savolainen, Peter T.; Schneider, Bill; Ghamami, Mehrnaz; Verma, Rajat; Fakhrmoosavi, Fatemeh; Kavianipour, Mohammad; Shojaei, Mohammadhossein; Singh, Harprinderjot; Zhou, Chao · 2018 · ROSA P / Michigan. Dept. of Transportation. Research Administration

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Summary

This study evaluates the effectiveness of a prototype Collision Avoidance and Mitigation System (CAMS) installed on winter maintenance trucks (WMTs) to reduce rear-end collisions. The research was motivated by the persistent safety risks associated with snow removal and deicing operations, where slower truck speeds, low visibility, and reduced pavement friction increase the likelihood of crashes with following motorists. The CAMS, developed by a private vendor, utilizes a rear-facing radar and camera to monitor approaching vehicles and activates a warning light bar when a vehicle encroaches too closely, defined by specific time headway thresholds. The primary objective was to determine if the system could improve driver behavior and reduce crash rates sufficiently to justify widespread implementation across Michigan. The evaluation was conducted during the 2017–2018 winter season using two MDOT and two Oakland County Road Commission trucks equipped with CAMS. The methodology included controlled field tests to calibrate warning thresholds (set at 7 and 5 seconds of relative headway) and operational field tests during actual plowing activities. Researchers analyzed logged data regarding vehicle detection accuracy, sensor cleanliness, and warning activation precision. Additionally, the study assessed driver behavior by measuring encroachment rates and response times when the warning light was active versus inactive. The evaluation also incorporated surveys of WMT drivers to gather operational feedback and performed a benefit-cost analysis based on historical crash data and estimated installation costs for a statewide fleet of 800 trucks. The findings revealed significant operational and performance issues that hindered the system's reliability. The integrated cleaning system failed to adequately remove debris, leading to persistent occlusion of the radar and camera sensors. Furthermore, the warning light activation was inconsistent, characterized by false positives triggered by vehicles in adjacent lanes and missed or delayed activations for vehicles actually encroaching on the truck. Despite these technical failures, the data indicated that when the system functioned correctly, it had the potential to positively influence driver behavior by improving reaction times and reducing encroachments. However, the benefit-cost analysis yielded a ratio of 0.85, suggesting that the current implementation costs are not economically justified by the estimated crash reduction benefits over a five-year lifecycle. The study concludes that while CAMS shows promise for enhancing safety, it is not yet ready for broad deployment due to critical hardware and software deficiencies. The authors recommend further investigation and remediation of the sensor cleaning mechanisms and warning logic algorithms before statewide implementation. The research highlights the necessity of robust, weather-resistant hardware for winter maintenance applications and underscores that economic viability depends on reducing installation costs or demonstrating higher crash reduction rates. Consequently, subsequent evaluation is required to address these limitations and validate the system's effectiveness in real-world conditions.

Key finding

The CAMS system demonstrated potential to improve driver reaction times and reduce rear encroachments but suffered from persistent sensor occlusion due to cleaning system failure and inconsistent warning light activation, resulting in a benefit-cost ratio of 0.85.

Methodology

field_study

Sample size: 2

Provenance

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Summary generated by qwen3.6-27b-prismaquant on 2026-06-10; verification: verified.

Topics

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• emergency work zone conspicuity