Air-brake systems rely on an engine-driven compressor to keep the reservoir tanks at their operating pressure. Coasting downhill and relying on the brakes to control your speed could result in the loss of sufficient air pressure to operate the brakes effectively.

You should take precautions against dropping mud on the road, because it's a hazard to other road users. It's also an offence for which you could be prosecuted.

Understanding other road users' behaviour can help you anticipate their next action. On this occasion it could prevent a serious incident. This type of assessment is part of the forward planning of a professional driver.

To work out your vehicle's payload, use the following formula: maximum authorised mass (MAM), minus tare weight, equals payload. This is the maximum weight your vehicle can carry.

If any animal you pass on the road becomes unsettled, you should brake gently and come to a stop. A nervous animal is unpredictable, so you should wait until it has settled or passed by. Other road users behind you may have a limited view of the hazard, so use your mirrors and give clear signals if necessary.

If you're carrying a steel ISO (International Standards Organization) cargo container, ropes or straps won't be strong enough to take the strain. This type of load requires a special type of restraint using twist locks.

Hitting the kerb at speed can split the tyre or put the steering and suspension geometry out of alignment. Have it checked as soon as possible. A sudden puncture in a front tyre could result in a loss of steering control and a serious crash.

The type of training required by drivers carrying livestock varies according to the distance, journey duration and species involved. For journeys of less than 65 km (40 miles), no formal qualification is required but you must have practical experience in the care of animals being transported.

When discharging a load from a tipper vehicle, the centre of gravity is raised as the tipper body rises. To avoid the vehicle rolling over, it's vital that it's positioned on a level, solid surface before the tipper mechanism is engaged.

If you become aware that any part of your load is insecure, you must stop as soon as it's safe to do so. Resecure the load before continuing your journey. If this isn't possible, then you must seek assistance. Don't take risks.

SRVIs are more evident in young male drivers, who tend to ignore or deny how they're feeling. The greatest risk is between the hours of 2.00 am and 7.00 am, when the body clock is in a trough. Make sure you take sufficient rest breaks and don't ignore feeling sleepy.

Drivers are required to take 35 hours of training every five years to maintain their Driver CPC. This can be split into shorter sessions of at least seven hours each. These can be spread over the five years, so effectively one day's training is taken each year. The penalties for non-compliance are the same as those for driving without a licence.

It's important to use a low gear and keep the engine speed high to prevent water from entering the engine through the exhaust system. In these circumstances, it may be necessary to slip the clutch to keep the road speed as low as possible.

In queuing traffic, motorcyclists may take the opportunity to filter between the lanes. Be aware that they may pass on either side and very close. Stay alert and always check your mirrors and blind spots before moving off, changing lanes or turning.

Fuel spilled on the road is a serious danger to other road users, especially motorcyclists. To prevent this from happening, make sure the filler cap is secure after refuelling.

A green flashing light on a vehicle means the driver or passenger is a doctor on an emergency call. Give way to them if it's safe to do so. Be aware that the vehicle may be travelling quickly or may stop suddenly.

Goods and passenger vehicles with a MAM of more than 7.5 tonnes, those required to be fitted with a speed limiter, and vehicles towing trailers must not use the right-hand lane on a motorway with more than two lanes, unless there are exceptional circumstances.

Drivers' hours and rest periods are controlled in the interests of road safety. A driver's daily rest period should normally be 11 hours, but this may be reduced to 9 hours up to three times between weekly rest periods. It's a serious offence to break these rules and anyone doing so is liable to a heavy fine and even imprisonment.

Air suspension provides a smoother journey than traditional suspension and transmits less vibration to the road surface, under-road services and nearby structures, such as bridges. It's considered to be environmentally friendly because it reduces damage to the road network.

Following the vehicle manufacturer's guidelines for service intervals will enable worn components to be replaced before they fail. This will help prevent costly breakdowns.

Some foods need to be transported at controlled temperatures. Drivers will need to be trained in the use of refrigeration units and correct hygiene procedures.

Before overtaking assess the situation. Look well ahead to see if the cyclist will need to change direction. Be especially aware of the cyclist approaching parked vehicles as they will need to alter course. Do not pass too closely or cut in sharply.

Emergency refuge areas may be found next to the hard shoulder on a smart motorway. If possible, you should use one of these areas, rather than the hard shoulder, when you break down. If the hard shoulder is being used as a running lane, take care when you rejoin the motorway.

You should use a suitable restraint and chock the wheels when another vehicle is being carried piggyback. Don't just rely on the other vehicle's parking brake.

When you need to drive close to the kerb, be aware of the dangers.

• Pedestrians may step off the kerb.
• The nearside mirror may be at a pedestrian's head height.
• Cyclists may be tempted to pass you on your left if you're driving slowly in congested conditions.

When driving downhill, gravity will cause the vehicle to increase speed. More braking effort will be required, and stopping distances will increase.

You should always plan your route. This will ensure you always drive on roads that are suitable for the size and weight of your vehicle. By planning to avoid peak travel times, you can also avoid congestion. This can save you fuel, as well as reducing your journey times.

Sulphur produces acidic gases. Diesel fuels with lower sulphur content have been produced to reduce exhaust emissions that harm both people and the environment.

Parked vehicles near junctions can hide smaller road users such as cyclists and motorcyclists. Double-check before emerging with a large vehicle. If in doubt, move forward slowly into a position where you can safely have another look.

On a motorway, it's best to use a roadside emergency telephone so that the emergency services are able to locate you easily.

Even though a warning device indicates low air-brake pressure, you may still be able to release the parking brake. If you do this and start moving, the service brake may be ineffective and you may not be able to stop.

There are heavy fines for those convicted of bringing illegal immigrants into the UK. This can mean a fine for each illegal person carried. The fine can be imposed on each 'responsible person', including the vehicle driver, owner and hirer.

To make sure it's safe, you must use the mirrors well before you make any manoeuvre. For example, you need to use them before moving off, turning, overtaking, slowing or stopping, opening a door, or changing direction, lanes or speed.

Before overtaking, you need to make sure it's safe to carry out the manoeuvre. As part of your check, look well ahead for road junctions. You shouldn't overtake as you approach a road junction, because if a vehicle emerges, or has to wait to turn, you could risk a collision.

You should always be aware of the amount of room your trailer needs when it's going around bends and corners. If you need to go onto the other side of the road, make sure there's no oncoming traffic before you move out.

High-sided vehicles are severely affected by side wind because of the large surface area of the bodywork. The risk of loss of control is increased if the vehicle is unladen.

Bus-lane signs show the vehicles allowed to use the lane and its times of operation. Where no times are shown, the bus lane is in operation 24 hours a day.

Always be prepared to give way to overtaking lorries or buses. Maintaining your speed will only block the motorway to other traffic unnecessarily. You may find yourself in a similar situation if the limiter on your vehicle doesn't allow you enough speed to successfully overtake another vehicle.

When your steering wheels are locked - as can happen in a skid - you can't steer the vehicle. Anti-lock brakes help you to keep steering control while you're braking heavily, but they aren't a substitute for good forward planning. Anticipation and planning ahead will minimise the risk of skidding more effectively than relying on your braking system.

In the darkness, it will be difficult to assess the road ahead - especially if there are bends or hills, which may prevent you from seeing oncoming vehicles.

The forces acting on a lorry will try to move it in a straight line as it enters a bend. The greater the weight, the greater the force. If you're going too fast, there's a danger that you could lose your load or tip over.

By using a retarder, the life of the brake linings is extended. This is because a retarder works by slowing the vehicle without using the wheel-mounted brakes.

It's not always possible for drivers in the left-hand lane to change lanes to let joining traffic merge. However, you should be ready to adjust your speed to help the joining driver merge safely.

When approaching a tunnel, switch on your dipped headlights. Be aware that your eyes might need to adjust to the sudden darkness. You may need to reduce your speed.

Heavy braking can cause an articulated vehicle to become unstable and may even lead to jack-knifing; this is more likely to occur when the trailer is unladen.

While driving on a building site, bricks, mud or other debris can become lodged between a lorry's double rear wheels. When you leave the site and increase your road speed, anything lodged between the tyres could be thrown out. This flying debris can be a hazard for drivers of following vehicles and can create dangerous road conditions, especially for motorcyclists.

If you plan your journey to avoid busy times, you can avoid congestion. That way, your overall journey time may be reduced, so cutting costs and making you a more efficient driver.

Side markers must be displayed if your load is over 2.9 metres [9 feet 5 inches] wide. Make sure that they're clearly visible, at both the front and rear, and that they indicate the actual width of the projection.

The endurance brake (retarder) usually operates by applying resistance, via the transmission, to the vehicle's driven wheels. If the road is slippery, the tyres may lose grip and the wheels will lock.

When passing horses, allow plenty of space, slow down and stop if you need to. Animals are easily frightened by sudden or loud noises and can quickly become uncontrollable, so don't sound your horn or rev the engine.

Before leaving the cab, it's very important to secure the vehicle by applying the parking brake. After leaving the cab, apply the trailer parking brake.

In cold weather, diesel fuel can solidify as it starts to freeze. This is known as waxing. Waxing prevents the fuel from flowing properly and this can stop the engine from running.

As you pass pedestrians or vehicles on your left, you should use your nearside mirror and check that you've passed them safely. You need to allow a good safety margin before you move back to the left.

Drivers of vehicles carrying dangerous goods are required to hold an ADR driver training certificate. This certificate is valid for five years and is issued by DVLA when you've attended an approved course and successfully completed the examination.

Be aware of, and obey, all speed limits. On a motorway, any lorry that's articulated, towing a trailer, or over 7.5 tonnes mustn't exceed 60 mph (96 km/h).

High-value cargoes are often targeted by thieves. Operators are recommended to seek advice from their local crime-prevention officer to help prevent their vehicles and loads from being stolen.

Projection marker boards must be fitted if the load on your vehicle overhangs by more than 2 metres (6 feet 6 inches). This will help other road users who may not notice the projecting load.

A loose brake pedal would suggest a serious loss of fluid from the hydraulic system. Don't drive your vehicle until the fault has been checked and fixed by a qualified person.

Road-friendly suspension reduces the vibration caused by the impact of the wheels on the road surface.

An exhaust brake alters the engine's exhaust flow, using it to help control the vehicle's speed. It's most efficient when the engine is running at a high speed and the vehicle is in a low gear, such as when descending a long hill. Using the exhaust brake can relieve the service brakes, preventing them from overheating and fading.

If diesel fuel becomes very cold, it can partially solidify. Additives are used by the fuel companies to try to prevent this. Any solidifying (waxing) of the fuel can prevent it from flowing properly and cause the engine to run erratically or even stop.

Even though the warning light is showing, there may be sufficient pressure to release the parking brake. However, you mustn't do this, because there may not be enough air pressure to operate the service brake.

The main causes of lorries shedding their loads are driver errors, such as sudden changes of speed or direction, driving too fast for the conditions, and harsh braking.

Before leaving the cab, it's very important to secure the vehicle by applying the parking brake. After leaving the cab, apply the trailer parking brake.

Lanes at roadworks often have weight restrictions to keep larger vehicles in the left-hand lane. The lanes through the roadworks are often narrow and therefore not wide enough for large vehicles to pass each other safely. Always look for restriction signs at roadworks. They're usually placed well in advance to give you time to move safely into the correct lane in good time.

If you're involved in an incident in a tunnel, be aware of the danger this can cause to other traffic. You should immediately switch on your hazard warning lights and switch off your engine.

Off-road lorry and coach parks are often well lit and patrolled by police or security firms. Never leave your vehicle unlit on a public road or in a lay-by after dark.

Solid white lines are used where it would be dangerous to overtake. If the solid line is on your side of the road, you may cross it to pass a stationary vehicle, or to overtake a pedal cycle, horse or road-maintenance vehicle that's travelling at 10 mph or less. You may also cross the solid line to enter premises or a side road.

Leaving the filler cap off, or not properly securing it, could result in a spillage of diesel onto the road. Because diesel is slippery, this would be a major hazard, so make sure to correctly secure the filler cap after use.

Modern anti-lock braking systems rely on electronics for their operation. A warning light on the dashboard shows that the system is operating. This light will usually go out when the vehicle reaches about 6 mph (10 km/h).

Drivers need to be alert at all times. Fatigue is a recognised danger for professional drivers, so working conditions are governed by EU rules. These set a maximum driving time and minimum requirements for rest and break periods. Setting limits on the length of time a driver can work combats fatigue and so helps road safety.

You should always leave a safety margin between your vehicle and the one in front. This gap will give you a better view of the road ahead. It will also allow you time to react if the traffic in front changes speed or direction.

Load security is extremely important. Make sure you park legally and, preferably, in a well-lit area. Some lorry parks are patrolled regularly by the police or security services.

The term 'crawler lane' doesn't mean the lane is only for extremely slow vehicles. It's advising you of an extra lane on the left. Crawler lanes are usually built on sections of road where the length of the gradient is such that some large vehicles will be slowed to the point where they become a hazard for other road users.

Don't continue to drive if you feel the onset of tiredness. Find a safe place to stop for a rest. Walking around in the fresh air during your break will help but it's no substitute for adequate rest.

Don't frustrate other road users by driving for long distances with a queue of traffic behind you. This could cause them to lose concentration and overtake in an unsafe way. Stop where it's safe and let them pass.

Energy-saving tyres keep fuel costs down because they have a lower rolling resistance and better grip than ordinary tyres. You should consider this when replacing your tyres.

You mustn't park or stop on a road marked with double white lines (even where one of the lines is broken) except to pick up or set down passengers.

This is a warning sign to indicate loose chippings ahead. The sign is usually accompanied by an advisory speed limit. Vehicles travelling too fast for the conditions can throw up chippings or stones. Avoid causing damage to paintwork and windscreens by keeping your speed down.

It's important to stow away all your electrical cables and air lines safely to avoid causing injury to others. Connectors left lying around can be a trip hazard and can be damaged if they're run over by another vehicle.

All drivers should play their part to protect the environment against traffic pollution. Make sure the vehicle you drive is properly maintained. Report any defects, such as excessive exhaust smoke, as soon as you can.

When the amber light is flashing, you must give way to any pedestrians on the crossing. Don't be impatient or encourage pedestrians to cross by waving or flashing your headlights; they or other road users may misunderstand your signal.

The parking brake must always be set whenever you leave the vehicle. It's an offence not to leave your vehicle properly secured.

Correctly adjusted air deflectors will save fuel. They should be adjusted to guide the airflow over the highest point at the front of the trailer or load and body.

Tailgating' is the term used when a driver or rider follows the vehicle in front too closely. It's dangerous because it restricts your view of the road ahead and leaves no safety margin if the vehicle in front needs to slow down or stop suddenly. Tailgating is often the underlying cause of rear-end collisions or multiple pile-ups.

Your tachograph chart is a legal document; it's a record of your work covering a rolling 24-hour period. Drivers who break the rules are subject to heavy fines and could lose their vocational licence. Altering your tachograph chart with intent to deceive is against the law and could lead to a prison sentence. Similar penalties exist for those who permit such offences.

If you've been convicted of drink- or drug-driving, statistically you're a risk to yourself and others on the road. For this reason, when you're able to drive again, insurance companies may charge you a high premium to insure your vehicle.

Vehicles carrying loads between 4.3 metres (14 feet 1 inch) and 5 metres (16 feet 6 inches) wide are subject to lower speed limits. The limit depends on the type of road. On a motorway it's 40 mph (64 km/h), on a dual carriageway it's 35 mph (56 km/h), and on all other roads it's 30 mph (48 km/h).

Using the left-hand lane will make it easier for you to leave the roundabout. If you use the right-hand lane, there could be traffic on your left and in your blind spot when you reach your exit and try to move back to the left.

Causing excessive smoke is an offence and could contribute to causing an incident or collision. You could also end up creating serious traffic problems if your vehicle breaks down in a difficult location.

Always be aware of the height of the vehicle you're driving, particularly if you drive different vehicles. If you use a sat-nav, it may show you the height and weight limits on UK roads.

A buffer lane is used when the wind begins to cause a risk to high-sided vehicles. At other times, it will be a normal lane. Don't use the buffer lane unless your vehicle has been blown off course into the lane, or you need to use it to avoid an incident or collision.

When the trailer is loaded, the weight of the load presses the trailer tyres firmly onto the road surface, so improving the tyres' grip. Unladen, there is no load bearing down on the tyres, and under heavy braking the trailer wheels can lock or slide across the road surface, making the trailer more difficult to stop. Severe braking can result in jack-knifing: the trailer doesn't slow as quickly as the tractor unit and this causes it to pivot around the coupling.

A full category D licence entitles you to tow a trailer of up to 750 kg. If you wish to tow a trailer over 750 kg, you must pass an additional test.

When traffic is heavy, plan well ahead so that you don't block crossings. Leave them clear so that pedestrians can cross safely.

Oil is vital for lubrication of the engine. It should be checked regularly and topped up as necessary. You should always check your engine's oil level when the engine is cold and your vehicle is parked on the level.

If you see a vehicle with a green flashing light, it will be a doctor on an emergency call, so give way by pulling over and letting the vehicle pass. But don't just stop suddenly - choose a safe place as soon as you can to let the doctor's car pass safely.

To achieve maximum stability, the load should be placed to keep the centre of gravity as low as possible. To do this, heavy items should be placed close to the centre line and spread over the full length of the vehicle. Lighter items should be placed along the sides.