Suppose the employer had a crew of five road workers re-marking the road markings at midnight in Emirates Road.Suppose the employer had a crew of five road workers who were re-marking road markings in Emirates Road at midnight. The speed of traffic is 120 km/h. The crew is set up with cones. Crew comes up. The symptoms are present. Behind the crew, the single truck weights, its amber lights flashing, arrow board beaming and its crash cushion firmly planted on the back so no one has to take a beating.
The truck is a Truck Mounted Attenuator (TMA). Knowing how it operates is the reason why it is one of the most crucial safety equipment used on the UAE’s roads today.
What is a Truck Mounted Attenuator?
A Truck Mounted Attenuator is a crash cushion device that is attached to the back of a heavy duty shadow vehicle. It only serves as a bumper to stop the kinetic energy of a misdirected vehicle from reaching road workers in front of the truck, and limits the injury to the misdirected driver.
Trucks, cars and occupants are protected from a vehicle that bumps into the TMA cartridge even if it is hit from the side.When a vehicle is bumped by any other vehicle, the TMA cartridge will absorb the impact protecting the truck, the vehicle and the occupants. These vehicles are known by a variety of terms in the industry, including shadow vehicles, crash trucks, hero trucks, barrier trucks and impact attenuator trucks. They all tie into the same concept: a car that acts as a “sacrificial shield” between moving traffic and vulnerable workers on the road.
In the UAE context, there are roads such as Sheikh Zayed Road which has vehicles moving on it at high speeds and active construction and maintenance zones, so a TMA is not only good safety practice. It is required by Dubai RTA and Abu Dhabi ITC regulations to be used by most high speed work zone operations.
The UAE Road Environment makes TMAs Truck Mounted Attenuator essential, why?
The UAE road safety data is clear in how dangerous the road environment is for road workers every day. In 2024, Dubai had more than 2 million cases of radar infractions. The UAE Ministry of Interior reported 38% of all road accidents were caused by carelessness in the same year, while distracted driving led to 931 accidents across the UAE. In 2024, 87,321 additional drivers were arrested for using mobile phones while driving in Dubai.
Sadly, 384 road fatalities were reported across the UAE in 2024 — so driving on UAE roads is a very risky business for drivers and road users of the country’s highways. The top cause of accidents in Dubai were sudden lane changes, accounting for 676 accidents, while failure to maintain safe following distance came in second with 518 accidents.
Road workers work in the same environment, albeit at a slower pace. The vehicles drive at 100 km/h or higher while the maintenance crew works at virtually no speed to repair a pothole, repaint a line, or install a sign. Having a TMA in between them and that traffic can transform a normal road works assignment into a disaster. Once set in place, the same incident results in a repair job instead of a tragedy.
The physics behind how Truck Mounted Attenuator actually work
This is where it gets real — and more impressive than it looks — real engineering kicks in.
The attenuator is housed inside a truck and contains a series of energy-absorbing cartridges that are usually composed of aluminium honeycomb, steel struts or special composite materials. These cartridges compress in a well-designed succession when a car crashes into the back of a TMA at speed. It’s a simple concept, but it saves lives and is described in its entirety by the Arizona Department of Transportation — the attenuator box is filled with a honeycomb configuration of aluminium, foam, and air space.
The concept is that of progressive loss of energy. If a car collides with a hard wall, the kinetic energy is imparted virtually instantaneously to the vehicle’s structure and occupants and the effect is devastating. A TMA operates the other way around. The crushable cartridges are crushed in segments, extending the deceleration time and distance. The physics outcome is to reduce the G-force for the striking driver, so they and those who are ahead of the truck are not injured by the deceleration forces.
A TMA has to pass a controlled test in which a 5,000-pound pickup truck is driven head-on and at an angle into a TMA at 62 mph (around 100 km/h), a speed that is 100% of the maximum speed of UAE roads classified as MASH TL-3. If it works properly, the striking vehicle will decelerate safely, the TMA will absorb the impact, and the shadow truck will not send itself forward into the work zone. Before any TMA is rolled out on Dubai’s high-speed roads, it needs to clear this hurdle.
Also, the TMA has a second mechanical function in the event of impact: deflect the striking vehicle from the work zone. A curved side rail on devices such as the TrafFix Scorpion II offer complete 180° side impact protection and deflect vehicles away from the back of the truck. Even if it only rips a little off the road at an angle, it’ll pull back onto the road and away from the crew in the skid and ahead.
The Role of the Arrow Board, a guide to the circle of arrows
Do not use the arrow board as a decorative accessory on the top or above the TMA truck. It is the first line of active communication between the work zone and the approaching traffic and acts as an early warning system.
It’s common sight in the work zone to see oncoming drivers see a high-visibility LED arrow board to slow down and drive around the work zone safely. A driver should have a clear several hundred metres ahead to change lanes and have to decelerate from 100-120 km/h to safety. The arrow board gives that warning from a considerable distance in advance, affording distracted and inattentive drivers the time they would not have otherwise.
All attenuator and arrow board controls should be located within the cab to eliminate the need for the driver to get out of the cab to adjust the controls. When deployed, the bottom of the arrow board should be about 7 ft above the ground for the greatest visibility to approaching vehicle drivers. Lights on the truck must be visible from 360 degrees around the truck.
The arrow board and the crash cushion create a double protection system. The board decreases the chance of a collision. If prevention is not achieved, then the impact comes into the TMA.
Two operating modes (Stationary or Moving)
There are two modes of operation for an active TMA shadow vehicle, the positioning rules vary considerably between the two modes.
The TMA truck is in stationary mode, parked at a predetermined location upstream of the work zone with the parking brake applied, wheels chocked and attenuator in place and at proper height. The workers are separated from the truck by a 50–100 foot buffer area. This setup is a fixed barrier: any vehicle that does not merge off of the roadway prior to coming to the closure will be absorbed by the TMA.
The shadow vehicle is used to move the vehicle as the work operation is carried out with the work crew along the road. This is the case with operations such as lane marking, sweeping the roads, patching potholes and line repainting (as the crew can be seen moving around continuously and not in a single stationary spot). This mode, the shadow vehicle is always traveling 50-100 feet behind the work crew and adjusts its speed continuously to match the speed of the work crew. The TMA offers continual, moving protection that protects the workers as they move.
Shadow vehicles are moving trucks that effectively shield vehicles that are veering off course in traffic from hitting the workers directly in front of them. The crew on mobile activities (crack pouring, striping, coning, pavement marking, delineator repair) is in front of the shadow vehicle, behind which is the TMA truck, which is moving with the crew.The crew on the mobile activities (crack pouring, striping, coning, pavement marking, delineator repair) are in front of the shadow vehicle and behind is the TMA truck which moves with the crew.
What Happens After an Impact
A TMA is a special type of sacrificial device. If it gets hit, it does its duty — and when that’s done, it needs to get replaced before the work zone can continue. Collapsing attenuators are unable to protect the crew members after the impact because they are no longer structurally sound. It is a compliance violation and a true safety failure to continue running a work zone with only an impacted TMA unit.
UAE contractors having RTA work zones permits are required to replace an impacted TMA immediately. That’s why trusted TMA rental services in UAE can provide 24-hours swap services, which allow you to get a new vehicle when you need it most to ensure that your work zone remains compliant with the permitted work window.
(TMA) Truck Mounted Attenuator Requirements Under UAE Law
The legal aspects of TMA use on UAE roads are straightforward. Iowa’s Roads and Transport Authority requires all work zone traffic management plans to meet the requirements of the Work Zone Traffic Management Manual and include MASH TL-3 certification requirements for high-speed road environments. All contractors working on major roads within Dubai’s Right-of-Way are required to cover the costs of a Traffic Management Area (TMA) to be signed, stamped and approved prior to commencement work.
The UAE Federal Decree-Law No.14, 2024, on Traffic Regulation was introduced on 29 March 2025 and clearly states the responsibilities for all road users and work zone operators to comply with authorised traffic control measures. The consequences of non-compliance are fines, work stoppages or site closure.
The Integrated Transport Centre is responsible for high-speed work zone requirements in Abu Dhabi, which are similar for MASH certified TMA equipment and LED arrow board set up on an expressway.
During a Safety Summary, a TMA’s role is to do the following:
In summary, a correctly set up TMA with arrow board performs 5 functions at a UAE road work site. It alerts approaching traffic in visual fashion by the LED arrow board. Provides physical separation between the moving traffic and the work crew. Absorbs the kinetic energy of an off-track vehicle in a controlled and progressive manner. It deviates the striking truck away from the workers. And it provides the driver of the shadow truck with protection inside the cab throughout the event.
None of those five things is accomplished by any cones, sign or flagging arrangement. Therefore, the TMA is the standard, and not an upgrade.
Final Word
With a basic understanding of the operation of Truck Mounted Attenuators, it’s obvious that this isn’t over-ambitious bureaucracy. Each and every element, from the honeycombs on the cartridge to the curved aluminium side rails, the minimum weight requirements and the high-mounted arrow board, have come into existence after someone conducted experiments to see what would happen if physics meet human bodies in a work zone and designed a system to alter the results.
UAE roads saw 931 construction-related accidents in 2024 alone, and construction workers perform their tasks every day on the road alongside vehicles driving at highway speeds, which makes a certified TMA a difference between an accident that your project is able to recover from and one that it can’t.