an errant vehicle that collides with it, thereby protecting the truck, the vehicle, and the occupants of both.
One important purpose for the TMA's deployed on trucks and other vehicles, typically those used in highway construction, is for protecting workers in those vehicles. The trucks equipped with TMA's are referred to as shadow vehicles, barrier vehicles, and advance warning vehicles. Shadow vehicles are moving trucks that effectively block errant vehicles in the flow of traffic from striking the workers directly ahead of the truck. The protected workers typically perform mobile activities, such as crack pouring, patching utility work, striping, coning, pavement repair, pavement marking, and delineator repair, and the shadow vehicle moves with and behind the workers. Barrier vehicles are effectively used to protect vehicles in the flow oflarge forces that occur during an impact event. Attaching directly to the truck frame also requires skilled labor such as welders and machinists, and can typically take up to three days to complete the assembly and install the more complicated attenuators on the market today. The demand for a greater cost effective method of installation and ease of attachment has been identified by TMA manufacturers. As a result, TMA manufacturers have developed a line of Mobile Impact Truck Attached Attenuators (MITAA) which attach directly to a truck's pintle hook, rather than the frame.
The challenge of attaching an attenuator to the pintle hook is to prevent the attenuator from undergoing an angular rotation during an impact event. Attaching the attenuator to the pintle hook alone does not prevent the