A truck-mounted attenuator or TMA is designed to protect a road crew working on a road with active lanes of traffic by absorbing the energy of any vehicles which inadvertently enter the work zone and crash into it. The idea is that the TMA should first act as a warning device, which is why most TMAs are fitted with bright lights and high visibility paint. Secondly, the TMA is designed to crumple and absorb the shock of an impact and prevent any vehicle from reaching the crew who are at work in the road. However, it is important to realise that if an impact does occur, the TMA vehicle may be shunted forward by the force of the impact. The distance that the TMA truck will move depends on a number of factors which are outlined below. 

The weight of the TMA truck

When calculating the distance you need to leave between the TMA truck and the road crew, the first thing you should consider is the vehicle's weight. A light truck which is fitted with a TMA will move forward a greater distance than a heavier truck when a vehicle impacts it. If you are using a light truck, you should leave a greater distance between it and the work crew.

The type of vehicles which use the road

Next, you need to consider the types of vehicles which use the road you are working on. If you are working on a minor road, it is highly likely that the majority of vehicles which use the road will be cars. If a car hits a TMA, the amount of kinetic energy produced will be relatively small, which means that the distance it is pushed forward will not be very great. However, if you are working on the side of a busy highway, it is quite possible that trucks and other heavy vehicles will be on the road. If a fully loaded truck hits a TMA, it could be pushed a considerable distance, so you will need to increase the space between the TMA and your work crew.

The speed at which traffic is moving

Finally, you will need to consider the speed at which traffic is moving. Vehicles travelling at high speed will have much higher levels of kinetic energy than those which are travelling slowly. If you are working on a road which has a high-speed limit, you should keep this in mind when parking the TMA. However, if you are working on a residential street which has a low-speed limit, you can position the TMA closer to the work crew.

If you would like further advice, you should contact a company which specialises in TMA equipment. Click here to continue reading more about this topic.