User-centered Smart Traffic Sign Development Implementation Study

Summary

Flaggers maintain traffic flow through a work zone area despite a shutdown of lanes by providing temporary traffic control. In terms of occupational safety, flaggers have one of the highest risk jobs in the country, with 41 out of every 100,000 workers killed on the job each year. This project developed and tested technology for automatically detecting and documenting the occurrence of near-intrusions into a flagger-controlled work zone. The project developed a low-cost portable device for automatically tracking vehicle trajectories, detecting potential intrusions, and providing audio-visual alerts to warn any errant drivers who might cause a danger to flaggers and workers in the construction zone. A radar sensor on the device is deployed by using a telescoping pole and collects simultaneous measurements from approaching vehicles in multiple lanes.

Tests were conducted in six real-world traffic scenarios, including work zones at one rural location (Cook County), three urban locations (Saint Paul, White Bear Lake, and Eden Prairie), a synthetic urban zone involving pedestrian crossings (Saint Paul) and one suburban/rural location (Mound). Detailed results and analysis are presented in this report. The results indicate that multiple design iterations have improved the device and enabled it to work reliably - very few false alarms (if any) are triggered and the intrusion detection curves implemented in the system are verified to work well. The vehicles which were alerted using audio-visual warnings in the last work zone test responded appropriately with a majority of them slowing down in response to the alarms.