Avoid Deploying Automated Truck-Mounted Attenuators (ATMA) on Roundabouts or Unconventional Intersection Designs Until Further Research and Testing Is Done To Successfully Navigate Through Difficult Pathways.

Closed Loop and Pilot Field Study Assessed the Safety Impacts of ATMA for Florida Work Zones Using Dashcam Recordings, ATMA Log Files, Drones, and Manual Inspection.

Date Posted

Florida ATMA Pilot Demonstration and Evaluation

Summary Information

Automated Truck-Mounted Attenuators (ATMA) offer potential benefits for safety and operational improvements in mobile work zones by eliminating the need for a worker to operate an impact protection vehicle. The automated (driverless) ATMA system operates in a multi-vehicle leader-follower configuration where the truck-mounted attenuator truck is retrofitted with a variety of sensors and cameras that enable its automated capability. The human-driven leader vehicle transmits navigation data to the follower (driverless) ATMA vehicle using Vehicle-to-Vehicle (V2V) communications. This project piloted a demonstration of the ATMA technology on June 23, 2020, and evaluated its operational and safety functions in a closed loop course, as well as testing the feasibility of ATMA in active mobile work zones throughout Gainesville, FL, over a course of several weeks. A benefit-cost ratio was calculated based on crash reduction potential of ATMA over traditional Truck-Mounted-Attenuators (TMA), using crash data for Missouri, from 2012 to 2017, and crash cost data from Florida DOT (FDOT) from 2012 to 2016. For cost estimates, vendor-provided equipment, installation, and maintenance cost items were considered for FDOT’s pilot ATMA deployment.

Lessons Learned

  • Recognize that operator training is essential and critical. The operation of ATMA relies on a two-vehicle setup involving a human-driven lead vehicle. The decisions made by the lead vehicle's driver significantly impact the operational and safety performance of the ATMA, as well as the traveling public around the work platoon. Therefore, it is very important that the lead vehicle driver is properly trained to make accurate decisions under a variety of conditions. 
  • Review FHWA Short-Term, Short-Duration, and Mobile (STSDM) guidelines; as a DOT, potentially consider ATMA-specific guidelines for Temporary Traffic Control. This is critical since short-term mobile operations have unique characteristics, and with ATMA becoming more widespread, DOTs may consider developing guidelines tailored specifically for ATMA operations. 
  • Avoid deploying ATMA for roundabouts or unconventional intersection designs. This is important for better operation of ATMA in mobile work zones to minimize the challenges of navigating roundabouts or making U-turns, until further research and testing is done about successfully navigating difficult pathways.
  • Consider system enhancements to accommodate stop-and-go operations. This kind of enhancement would allow ATMA to operate under more realistic conditions where there is not always necessarily a fixed gap between the lead and follower vehicle. Furthermore, steps to mitigate atypical scenarios such as leader vehicle in reverse could be addressed.
  • Leverage the lateral offset feature in ATMA. A very useful feature of ATMA system is the ability to maintain a lateral offset distance of up to 12 feet, which could be leveraged by properly trained users in field operation when applicable and necessary.
  • Test ATMA without safety operator. All the testing in this study was performed with a safety operator in the supposedly driverless ATMA follower vehicle to avoid any injury risks to the testing crew. However, for more accurate results and better representation of the intended purpose of an ATMA vehicle on an open road, further calibration and testing needs to be conducted for ATMA without a safety operator in ATMA follower. 
  • Repeat tests periodically and store data for dissemination. Being a relatively new technology, performing more tests of ATMA over time and tracking its performance is very crucial. In addition, having a clearinghouse and data repository would be beneficial for a DOT and other agencies to have access to the performance data as a guiding best practice. 

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