Driver Knowledge Tests

Driving a road train or heavy combination vehicle up and downhill

Driving a road train or other multi-trailer truck configuration demands additional awareness and anticipation for what is happening ahead, particularly when navigating steep gradients. Road trains, due to their significant length and weight, present unique challenges when ascending and descending hills.

Uphill driving

Momentum and acceleration

When driving a heavy combination vehicle uphill, maintaining momentum is crucial. The sheer weight of the vehicle means that any loss of speed is difficult to recover. Before approaching a hill, a driver should choose a suitable speed to try to maintain enough momentum. This helps to counteract the gravitational pull that will slow the vehicle down as it climbs. On some gradients, it’s inevitable that the truck will slow down, but it’s important to try to avoid having to change gear as much as possible.

Gear selection

Proper gear selection is vital when driving uphill. Drivers should downshift to a lower gear before the incline begins. This allows the engine to operate within its optimal power range, providing the necessary torque to keep the vehicle moving. Selecting the correct gear early prevents the need for shifting mid-climb, which can lead to a loss of momentum and increased strain on the transmission. On very steep slopes the time between gearshifts results in a large decrease in speed that can catch out inexperienced drivers, leaving them with no choice but to change down a lot of gears to recover power or, worst case, stop completely and have to try to get moving again in a crawler gear.

Of course, if you are driving a truck with an automatic gearbox, you may not need to worry, but those with a Roadranger (click here for Roadranger training) must be thinking ahead.

If the surface is wet, it might be impossible to get moving again, necessitating a tow from another vehicle.

Engine performance and fuel economy

Climbing steep gradients will significantly impact fuel economy. High engine loads and lower speeds increase fuel consumption. To mitigate this, drivers should maintain a steady throttle and avoid unnecessary acceleration. Additionally, regular maintenance of the engine and drivetrain can ensure that the vehicle operates efficiently under load.

Safety concerns

Safety is paramount when driving uphill. A sudden loss of power or mechanical failure can lead to the road train coming to a stop on a slope, which can be hazardous. Therefore, ensuring that the vehicle is in good mechanical condition by conducting a pre-start check before embarking on a journey is essential. Drivers should also be aware of their surroundings and anticipate potential hazards, such as slower-moving vehicles or obstacles on the road.

Downhill driving

Good anticipation of the road ahead is crucial. Watch for signs indicating a steep descent ahead.

Momentum and braking

Descending a hill in any large, long, heavy vehicle requires careful management of momentum and braking. The single most important thing is to get to the right speed by the time you are at the top of the hill so that you don’t overwhelm the brakes.

The vehicle’s weight can cause it to accelerate rapidly downhill if there is brake fade, so it is crucial to control speed from the outset. Using the engine brake (also known as a Jake brake) and the retarder system can help manage speed without relying solely on the service brakes, which can overheat and fail under continuous use.

Gear selection

Similar to uphill driving, gear selection is critical when descending. Before starting the descent, drivers should select a lower gear to utilise engine braking effectively. This reduces the reliance on service brakes and helps maintain a controlled speed. Shifting gears while descending can be risky due to the potential for losing control if the vehicle gains speed too quickly.

Stopping distances

Stopping distances for heavy vehicles are significantly longer than for regular vehicles, especially when travelling downhill. Drivers must maintain a greater following distance from vehicles ahead to allow sufficient time to react and stop if necessary. Understanding the increased stopping distance is crucial for preventing collisions and ensuring safety.

Safety concerns

Safety when driving downhill involves several factors. The risk of brake fade or failure is higher due to the continuous braking required to control speed. To mitigate this, drivers should regularly check the condition of their braking systems and use engine braking to reduce heat build-up in the service brakes. Additionally, being aware of runaway truck ramps and other emergency stopping areas can provide a safe exit in case of brake failure.

Driving a road train uphill and downhill is a complex task that requires a deep understanding of vehicle dynamics, safety protocols, and environmental factors. By mastering gear selection, maintaining momentum, managing braking, and conducting thorough vehicle inspections, drivers can ensure safe and efficient operation. Continuous training and awareness of road conditions further enhance safety, making the journey smoother for both the driver and other road users.

Darren is an expert on driving and transport, and is a member of the Institute of Advanced Motorists

Posted in Advice