Optimize TMA Markings for Motorist Compliance
The goal of truck-mounted attenuators (TMAs) is to alert the traveling public to the presence of road construction and maintenance activities, as well as to shield those crews in the event of a crash. Since 2015, the state of Virginia has experienced annual increases in TMA crashes.
That’s why the Virginia Department of Transportation sponsored the study “Strategies to Reduce Truck Mounted Attenuator Crashes”, performed by the Virginia Tech Transportation Institute (VTTI), to examine the effectiveness of various TMA markings and their influence on driver behavior.
VTTI parked a TMA truck on the right shoulder of US 460 in Blacksburg, Virginia, between Tom’s Creek Road and North Main Street, and collected data on the lane selection and speed of traffic that traveled past the truck based on a number of TMA treatments with various color schemes, patterns and the presence of an upper marking panel.
The goal was to identify TMA treatments that encourage drivers to shift to the left lane and reduce their speed as they approach the TMA, thereby potentially reducing the likelihood of a collision.
Among the different TMA treatments tested, the green/black chevron pattern with an extra upper panel showed the most promise in improving safety, with a left lane occupancy rate of 78% and speed reduction average of 50 mph. In contrast, yellow/orange chevrons were less effective, showing lower left lane occupancy (69%) and a higher average speed of approximately 56 mph. The standard yellow/black chevrons, used by the majority of surveyed DOTs, showed moderate effectiveness with 73% left lane occupancy and an average speed of approximately 55 mph.
The study also observed that treatments resulting in the most significant reduction in average speed also led to the highest speed variation. The research team believes that a slower average speed is a more significant safety benefit, offsetting any impact of increased speed variation. However, they note that a long-term data analysis is required to confirm this hypothesis.
Ultimately, the researchers emphasized the need for further research before changing the standard TMA pattern, including investigating additional patterns and color schemes and evaluating the effectiveness of TMA treatments in more diverse conditions, including nighttime operations and different road environments.
Despite the study’s limitations, one valuable take-away is that there seems to be room for improvement when it comes to the most common standards for TMA markings.
Best Practices for Enhancing Truck-Mounted Attenuator Safety
Before VTTI decided to study TMA marking patterns and colors for field testing, the researchers performed a literature review identifying existing research on TMA crash countermeasures that could enhance road safety. Here are 10 findings from studies VTTI referenced in its literature review.
- Consider Colors and Patterns for Enhanced Visibility
Traditional yellow and black chevrons are effective, but exploring a range of patterns like checkerboards and diverse colors could significantly improve visibility. Fluorescent yellow-green and black checkerboard patterns have shown promising results in vehicle identification during tests. Utilizing high-quality retroreflective sheeting in various colors can improve TMA visibility, especially in low-light conditions.
- Optimize TMA Truck Lighting
Lights should be bright enough for clear visibility, but must avoid causing glare which can distract drivers. Investigating the use of different colored lights, beyond the standard amber, can be beneficial. Green lights, for example, have shown promising results in reducing vehicle passing speeds. Implementing synchronized or sequential flash patterns could aid in better hazard perception and navigation.
- Effectively Use Dynamic and Static Signage
Dynamic speed feedback signs have proven more effective than static signs in changing driver behavior, especially in work zones. However, all signage should convey clear and concise information about the work zone to drivers to enhance awareness and reaction time.
- Enhance Seatbelt and Seat Design
Implementing pre-tensioning seat belts can improve occupant restraint, reducing the likelihood of injury. Incorporating seats with energy-absorbing functionality and better backrest designs can further mitigate injury risks.
- Utilize Intelligent Transportation Systems
Pre-collision alert systems, like directional audio alarms and radar-based intrusion alarms, can provide early warnings, enhancing safety for both workers and drivers. Additionally, implementing vehicle-to-vehicle and vehicle-to-infrastructure communications can dramatically improve situational awareness in work zones, providing real-time updates and warnings.
- Improve Seat and Cockpit Safety
Adjusting seat positioning for optimal safety and utilizing materials like memory foam can reduce the risk of injuries. Additional airbags and improved seat designs can also offer better protection for TMA operators.
- Maximize Flexibility with Programmable Warning Lights
Using customizable, programmable warning lights allows for adapting to various environmental conditions, ensuring effective visibility without causing glare.
- Enhance Lights with Sensor Technology
Equipping TMAs with sensor-activated rear lights can significantly increase their visibility for approaching vehicles, thus enhancing safety.
- Investigate Automated TMAs for Reduced Human Risk
The use of automated TMAs can minimize the risk to human operators, especially in high-traffic or complex work zones.
- Stay Informed on Emerging Research and Technologies
Continuous research and assessment of TMA safety features are crucial for adapting to evolving road conditions and emerging technologies.
Of course, applicable federal, state and local regulations must be considered. However, the extensive body of research on TMA best practices certainly offers food for thought on how our industry might enhance the effectiveness of TMAs in work zones and thereby improve safety in our work zones.