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.

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.

This sign is shown where slow-moving vehicles would block the flow of traffic. However, if you need to slow down to avoid an incident, you should do so.

It's dangerous to drive a vehicle with low air pressure. To alert you to this, all vehicles are fitted with a warning light and/or buzzer. Don't move your vehicle if this warning shows or sounds.

The maximum speed for lorries over 7.5 tonnes maximum authorised mass on a dual carriageway in England and Wales is 60 mph. In Scotland, the limit is 50 mph. Be aware of the speed limits applying to different types of vehicle on particular roads. This is the maximum speed allowed, but it may not always be safe to drive at this speed, because of the weather, volume of traffic and other factors.

Warning buzzers are linked to many systems on modern vehicles, including the air brakes. A warning light on the dashboard may help you identify the system that's caused the problem. Stop in a safe place until the fault has been identified and put right. Get professional help if necessary.

You must always be aware of the size of your vehicle. Look out for road signs that show a width restriction. There should be an indication of this at the entrance to the road. Don't get into a situation where you have to reverse out of a narrow road because you haven't seen a sign.

Overloading a vehicle is dangerous. Your stopping distance will increase, and your vehicle could become unstable and difficult to control. You'll need to work out the payload. Do this by taking away the kerbside weight from the maximum authorised mass (MAM). This will give you the maximum weight you can carry.

The smallest lapse in concentration can result in loss of control. Even when your tachograph would allow you to drive for longer, stop somewhere safe and rest if you feel your driving may be affected by your tiredness.

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.

The 'stop' sign is the only road sign that's octagonal. This is so that it can be recognised and obeyed even if it's obscured (for example, by snow).

Warning lights show when there's danger ahead. This includes

• lane closures
• incidents
• fog
• icy roads.

When braking a vehicle carrying a liquid load, it's important to apply even pressure on the brake pedal. Don't relax the pedal pressure until the vehicle has stopped. Secure the vehicle with the parking brake before releasing the footbrake; this will minimise the risk of unintentional movement of the vehicle caused by 'surge' from the liquid load.

If your vehicle breaks down, try to stop on the left, facing in the same direction as the flow of traffic. This will help other drivers to see you, as your red reflectors will show to the rear. Don't stop on the pavement, as the weight of the vehicle may damage paving stones and underground services.

It can be frustrating and worrying to find your planned route is blocked by roadworks or diversions. If you've planned an alternative, you'll feel less stressed and able to concentrate fully on your driving. If your original route is mostly on motorways, it's a good idea to plan an alternative using non-motorway roads. Always carry a map with you just in case you need to refer to it - but stop driving before you do so.

Some vehicles are fitted with an audible warning device that sounds when the vehicle is being reversed. As these devices make a loud noise, they shouldn't be used between 11.30 pm and 7.00 am in a built-up area. Audible warning devices are an effective safety feature, but they don't take away the need to use effective observation around the vehicle before and while reversing.

It can be dangerous for vehicles passing close by if you open the door carelessly. Always look properly to make sure that it's safe - checking the blind spots as well as using the mirrors - before you get out of the cab.

The formula used to calculate the payload of a vehicle is the maximum authorised mass (MAM) minus the tare weight. The tare weight is the total weight of the vehicle, including the crew and extra equipment.