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.

Suspension faults may result in road damage. Road-friendly suspension reduces the impact on the environment, the road surface and under-road services.

High vehicles are often directed to the centre of the road to go under an arched bridge. Check that your vehicle doesn't exceed the height restriction indicated. Plan your route in advance to avoid any bridges that your vehicle won't be able to clear.

Expect a motorcyclist who makes a quick glance over their shoulder to be changing direction. They should do this before turning. By observing this, you'll get an early clue of their intention.

The view you get in your mirrors may vary, depending on the size of the trailer and the load it carries. Always adjust your mirrors to ensure that you have the best possible view down each side of the trailer before you drive away.

Power-assisted steering operates when the engine is running. If a fault develops, much greater effort is required to turn the steering wheel. Don't attempt to drive a vehicle if you're aware of a fault in the power-steering system.

Current legislation requires all operators to set up an 'effective system' to help prevent the carriage of illegal immigrants. This should include vehicle security and checking using a checklist. Failure to do this will incur penalties.

Any medical condition that could affect your ability to drive a lorry or a bus safely may prevent you from holding a licence. These conditions include serious visual impairment, heart disease and some mental disorders. For more information about medical standards, you should contact the Drivers Medical Branch, DVLA, Swansea.

A person who's hysterical may do things that you wouldn't expect. Try to keep the distressed person calm and safe until the emergency services arrive.

When transporting livestock, it's important to limit the amount of space they have to move around. If you allow them to move around freely, it could increase the risk of injury to the animals. It will also affect the stability of the vehicle when braking and cornering, and could even cause the vehicle to tip over.

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.

If your suspension is damaged, all the weight of the vehicle compresses the road and anything located below it. The vibrations travel through the ground and can also damage surrounding buildings.

You must show consideration to other road users. Elderly drivers may have slower reactions and they might need more time to deal with a situation. Be tolerant and don't lose patience or show your annoyance.

Tailgating' - travelling too close to the vehicle in front - is very dangerous, because it doesn't give you enough distance to stop safely. Leave at least a two-second gap in good conditions, and increase this to four seconds in wet weather.

It's important that you always select a place to park that's both safe and legal. Don't park on or too close to a pedestrian crossing or a school entrance; this would restrict the view for drivers and pedestrians. Don't park at a bus stop either, because buses would then have to stop in the road, creating a hazard for other traffic and for passengers getting on or off the bus.

When you drive too close to the kerb, there's a risk that your nearside mirror could strike the head of a pedestrian. Be aware of this hazard and, if you see pedestrians close to the road, make sure you leave them enough room.

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.

Look for and obey traffic signs. Disobeying or not seeing a sign could be dangerous. It may also be an offence for which you could be prosecuted.

If the brake pedal is hard to press, this could mean a loss of vacuum or a fault in the vacuum pump. You shouldn't drive the vehicle until the fault has been repaired.

On the approach to many tunnels, a board will indicate a local channel or radio frequency that you should tune into. This should give a warning of any incident or congestion in the tunnel ahead. Severe loss of life has occurred in tunnel fires. Getting advance warning of any problems ahead will help you to take appropriate action in good time.

In exposed places, such as high-level bridges, viaducts or some motorways, high winds can cause the road to be closed to certain vehicles. If you're driving a high-sided vehicle and high winds are forecast, plan an alternative route in case your intended route is closed.

When passing through immigration control, you should have a list of all your passengers. They must all be accounted for.

Never commit yourself to overtaking unless you're absolutely certain that you have the time and space to complete the manoeuvre safely. Don't take any risks that will endanger other road users.

It's illegal to drive a vehicle that's emitting excessive exhaust smoke, so you should get the problem fixed as soon as you're aware of it. Excessive exhaust smoke increases pollution and creates a hazard for other road users.

Under no circumstances should you attempt to move or drive a vehicle with an air leak in the braking system. Report the fault immediately, or arrange to have it repaired. Place a warning sign in the cab, telling other drivers not to drive the vehicle and why.

You must be aware of the position of other road users, so that you know how they may be affected by your actions. Before opening your door, it's important to check the mirrors, as well as looking around for passing or approaching vehicles and pedestrians.

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.

Your vehicle will make more noise than a car, so you should try to avoid making unnecessary noise at any time of the day or night. This is especially important when you're in a residential area at a time when people are likely to be sleeping.

Applying a firm, continuous brake pressure will enable the anti-lock braking system (ABS) to function properly. However, ABS is becoming increasingly sophisticated, so you should read the vehicle manufacturer's handbook for its advice about using the system.

You must check the nearside mirror during and after overtaking a motorcyclist. Make sure that the rider is still in control and that your vehicle's draught hasn't caused them to lose their balance.

Overloading an axle has an impact on the environment, causing damage to road surfaces. You also risk a fine and driving penalties.

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.

If the load isn't covered, rubbish can be blown onto the carriageway. This can cause danger for other road users, as well as environmental damage. It may also lead to legal action against both the driver and the operator.

Learner drivers are often nervous. If you stay well back, this will reduce the risk of incidents occurring if they make a mistake, and you won't intimidate them. Remember, you were once in that situation yourself.

You have a responsibility to be aware of the dimensions of your vehicle, including ground clearance. When planning your route, you'll have to consider whether the roads you intend to use have any limits that would apply to your vehicle, such as

• weight
• length
• height
• ground clearance.

If you feel the onset of tiredness, you need to take a break. This might be at a motorway service station, but if there isn't one nearby you'll need to leave at the next exit and find a safe place to stop and rest.

Pedestrians who are part of an organised walk using the road at night should wear bright or reflective clothing. The walker in front should display a white light, while the one at the back should display a red light. Be particularly careful, slow down and give the walkers plenty of room.

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.

Depending on road speed, pressing the accelerator pedal firmly to the floor will activate a switch that allows the gearbox to select a lower gear for improved acceleration.

Before you make a turn or a change of direction, however slight, you should always check the mirrors. If you intend to turn left, check your left-hand (nearside) mirror first.

Large vehicles can be fitted with various types of endurance brake (retarder). Make sure you're familiar with how the system operates on the vehicle you're using. Don't risk a crash or collision through ignorance.

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.

Wet roads will increase the time it takes you to stop. Four seconds is the minimum gap you should leave on wet roads. This is double the gap you should normally keep from the vehicle in front on good, dry roads.

Slow down when you see a warning sign for an uneven road. Be especially careful if you're carrying passengers, livestock or fragile items.

Codes are shown on the wall of the tyre. These refer to the maximum load and speed capability of the tyre.

If you're taking medicine or drugs prescribed by your doctor, check that they won't affect your driving. If you forget to ask when you visit the surgery, check with your pharmacist.

To increase stability and reduce the risk of the trailer wheels lifting when turning, it's preferable to locate part-loads over the rear axle(s).

Engaging the diff-lock means that the driven wheels are locked together. This reduces the likelihood of wheel spin. Remember to switch off the diff-lock as soon as you're on firm ground again, otherwise you could damage the transmission.

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.

Better knowledge and use of fuel-efficient driving techniques can result in lower fuel consumption and emissions. Other benefits include improved road safety and greater professionalism.

Endurance brakes or 'retarders' help to control a vehicle's speed. They operate by applying resistance to slow the vehicle without using the wheel brakes, so avoiding brake fade. The methods used include: increased engine braking, exhaust braking and transmission-mounted devices.

You should warn other road users that there has been a incident. You can do this by displaying an advance warning triangle or by switching on hazard warning lights or other lights. However you choose to warn people of the incident, make sure it doesn't put you or others at risk.

In good dry conditions, you should leave a two-second gap between your vehicle and the one ahead. When the weather is bad, you'll have to keep a greater distance, because it will take you longer to stop. In wet weather it will take up to twice the distance; in icy weather this could increase to ten times as far.

Check all medicines for their side-effects, such as drowsiness. If you're unsure, ask your doctor or pharmacist to explain how you might be affected by the medication.

You can help someone suffering from shock by talking to them and reassuring them confidently. Don't leave them alone or give them anything to eat or drink.

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.

This sign gives you advance warning of a junction where the permanent sign is obscured by roadworks.

Motor vehicles over 7500 kg maximum authorised mass (MAM) and trailers over 3500 kg MAM should have these markings fitted to the rear of the vehicle/trailer.

Warn other traffic of the incident, without putting yourself or others at risk. Once the danger of further collisions is dealt with, call the emergency services. While you're waiting for them to arrive, keeping casualties or witnesses calm is important, but never offer a cigarette because of the risk of fire.

When an ambulance is displaying a flashing blue light, try to stop in a safe place to allow it to pass. Make sure you don't endanger any other road users or commit an offence; for example, by driving past a red traffic light.

In windy weather, exposed stretches of road may have lane closures or there may be diversions for some types of vehicle. Consider this when you're planning your journey; delays will add to your driving time.

Wide loads are a hazard to other road users. In addition to having an attendant with you, you must notify the police if your load is wider than 3.5 metres [11 feet 5 inches]. Side markers must also be used to show other road users the limits of your vehicle.

Just before turning, a check in the offside mirror will help you to see any cyclist or motorcyclist passing on your offside. This check may help to prevent a serious incident from developing.

In very wet conditions, tyres may be unable to clear all the water from their path. This can result in a layer of water building up between the road and the tyre - a situation known as aquaplaning. To regain control, ease off the accelerator and, as the vehicle slows, the tyres should regain their grip. It's safer to reduce the risk of aquaplaning occurring by driving more slowly in very wet weather.

When there's no traffic ahead of you, you should always drive in the left-hand lane.

Avoiding busy times means that you're not adding needlessly to traffic congestion. Other advantages are that you'll use less fuel and you may have an easier journey, making you feel less stressed.

Use your hazard warning lights on a motorway or unrestricted dual carriageway to warn following drivers of an obstruction or hazard ahead. This will alert drivers who may not be able to see the hazard due to the size of your vehicle.

Driving slowly will give you better control of your vehicle. By using a high gear, you reduce the chance of your wheels spinning and skidding on the snow.

Be courteous and prepare to stop. Don't wave people across, as this could be dangerous if another vehicle is approaching the crossing.

Concentration will be improved by eating regular, light meals timed to fit in with your scheduled rest periods. If you don't eat at all, your blood sugar levels will drop and you'll feel tired. If you just eat snack foods, most of which are sugary or high in fat, your energy levels will peak and then drop - and eating while you're driving is a dangerous distraction.

If you demount the body on a poor or soft surface, there's a danger of it sinking and becoming difficult to handle. Always think carefully before you demount the body and be sure that the site is suitable.

If you stop for pedestrians and they don't start to cross, be patient. Don't wave them across or sound your horn. This could be dangerous if the driver of an approaching vehicle isn't aware of them. The driver may not have seen or heard your signal, making it very dangerous for the pedestrians to start to cross.

When you're being overtaken, the other driver has to decide when it's safe to complete the manoeuvre. Don't give an unofficial signal, however well intended. There may be a hazard you're unable to see from your position.

If you need to brake when the road surface is wet, do so while your vehicle is travelling in a straight line. This will reduce the risk of skidding. As a professional driver, you should routinely brake in good time, so that you don't brake and change direction at the same time.

Misuse of drugs and/or alcohol may lead to the withdrawal of your driving licence. Future insurance premiums will probably increase as well.

Cold water will cool the burning tissue and help prevent further damage. It will also reduce swelling, minimise shock and alleviate pain. Use water, or any other liquid, that's clean and non-toxic.

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.

If you're following cyclists onto a roundabout, be aware that they might not take the exit you expect. Cyclists approaching in the left-hand lane could be turning right but may not have been able to get into the right-hand lane. Give them plenty of room.

Some highly dangerous chemicals have to be transported at prescribed temperatures. Drivers must be fully trained in the use of these specially designed, temperature-controlled vehicles.

ISO (International Standards Organization) cargo containers should only be carried on lorries or trailers with the appropriate securing points. These are designed to lock into the container body.

If you know which light is going to show next, you can plan your approach. This will help prevent excessive braking or hesitation at the junction.

A significant number of sleep-related vehicle incidents involve commercial vehicles. There's a particular risk when driving between 2.00 am and 7.00 am, because this is when the body clock craves sleep. It's important to take proper rest before, during and between driving duties.

A driver's week is defined as a period from 00.00 hours on Monday to 24.00 hours the following Sunday.

EU drivers' hours regulations are a series of rules that specify maximum driving time and minimum rest and break periods. These rules are in place to help road safety. Drivers who break them are subject to heavy fines and could lose their licence to drive lorries.

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.

DVSA and the police carry out frequent roadside checks of commercial vehicles. Where serious defects are found, the vehicle is taken out of use until they're put right. Details of the prohibition are shared with the traffic commissioner.

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.

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.

At hump bridges, there's a risk of long vehicles grounding. If you aren't sure whether the floor of your vehicle will clear the bridge, find another route.

Some medicines can have side-effects that affect your driving. Ask your doctor whether you'll be safe to drive while taking the medicine that's been prescribed.

High-sided vehicles such as box vans are affected by side wind, particularly when they're empty. Drivers should slow down and stay alert for other road users affected by the windy conditions.

If a police officer signals for you to stop, stop as soon as possible in a safe place on the left.

Other road users can be affected by the spray from large vehicles, severely reducing their vision. Always take care when you need to change lanes: signal in good time and watch your mirrors carefully before pulling out in these conditions.

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.

Look out for variable-message warning signs telling you about

• lane closures
• speed limits
• hazards.

When you're clear of the restriction, you'll see a sign telling you that it has ended.

This mirror is specifically positioned so that the driver can see the position of the front nearside wheel in relation to the kerb. Use it when pulling in to park alongside the kerb or when you have to move close to the left in normal driving.