White boxes allow you to unload at any time, but during the day the length of stay is restricted. You should check nearby signs for the specific times. At other times, when it's not so busy, there may not be any restrictions on parking.

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).

You must take care when approaching any hazard where height is limited. Know the height of your vehicle and what you can drive under safely. If you aren't sure that it's safe, take another route.

Hitting a bridge with your vehicle can have serious consequences for road and rail traffic. You must tell the police about the incident immediately. If the bridge is a railway bridge, call the railway authority as well as the police to report the incident.

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.

A vehicle is most stable when travelling in a straight line under gentle acceleration. Sudden acceleration, steering or braking can cause severe loss of control. For maximum control, keep your driving as smooth as possible.

It's a legal requirement that information about a vehicle's height can be seen by the driver from their seat. It's important to know the height of your vehicle so that you can avoid any height restrictions on your route.

Every year, there are hundreds of incidents in the UK where vehicles hit railway or motorway bridges. Most involve buses, coaches and lorries. Make sure your route doesn't take you under a bridge that's too low for your vehicle. If you hit a bridge, you'll be putting yourself and any passengers at risk, and you could cause a major disruption to road and rail transport.

The longer top deck needs a wider turning circle than the cab below it. To avoid hitting lampposts, telegraph poles, etc, you must allow for this overhang when turning.

If you're driving a high vehicle, make sure that there's enough headroom available for you to go through the tunnel. There may be additional signs showing height and width restrictions.

It's vital that you give yourself enough separation distance when driving on icy roads - ten times as much as in normal conditions. You should brake gently to reduce the risk of losing control.

To prevent your wheels from locking, you'll need to brake very gently on ice. Give yourself as much room and time as possible to stop. If your front wheels lock, you can't steer, and that will mean you can't avoid any obstacle in your path.

The transition from 'rear wheel lift' to 'roll-over' is more rapid on vehicles equipped with air suspension systems. Make sure you take advantage of any extra training that may be available to drivers of this type of vehicle.

Always look out for road signs, but be especially aware of those that refer to large or heavy vehicles. Get into the habit of checking for signs at junctions. There might be an indication on the junction layout sign. Before you turn, make sure that the road you're using doesn't have any restrictions for the vehicle you're driving.

The marker boards should be red and white. They must be kept clean and independently lit at night and in poor visibility, so that other road users can see them.

You should tell telephone companies about your intended route when planning the movement of loads over 5.25 metres [17 feet 6 inches] high. You should tell them in plenty of time before making the journey.

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.

If your vehicle is over 17 metres (55 feet) long and you wish to cross a level crossing, you must stop before the crossing and telephone the signal operator.

Plan well ahead before overtaking. Be aware that a speed limiter may cause you difficulties when overtaking another vehicle, particularly when climbing a hill.

Traffic-calming measures are becoming more common. Look out for signs warning you of humps in the road ahead. If necessary, change your route rather than take risks.

Look out for signs giving you advance warning of height restrictions. As a professional driver, you should always know the height of your vehicle or load. If you aren't sure of the safe height, stop and check.

If your vehicle is too long to fit into a passing place, you may need to wait opposite one. This will allow a following or approaching driver to pass. When you use this type of road, you need to plan and look well ahead to avoid meeting another road user at an inappropriate place.

You should be familiar with the room your vehicle needs to make turns or carry out a manoeuvre. You'll need to consider this as you approach junctions and road layouts. If you're driving a new or temporary vehicle, familiarise yourself with its characteristics before you drive on public roads.

As the top deck is longer than the cab and trailer, it will take up more room as the vehicle turns; you must make sure that you've allowed for the wider swing of the deck. Even if your cab is well clear, the overhanging deck could hit obstructions such as telegraph poles or traffic signs as you go round a corner.

All vehicles over 7.5 tonnes maximum authorised mass must have markings on the rear of the vehicle. These markings are rectangular and are coloured red and yellow. They're there to inform other road users of the characteristics of your vehicle. The markings should be kept clean so that they can be seen clearly at all times, especially at night and in poor visibility.

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.

Most speed limiters work by taking a speed signal from the tachograph and transmitting it to the engine management system. This reduces the fuel supply to the engine, and allows the speed of the vehicle to be controlled to specific limits. The speed at which a limiter is set must be shown on a plate clearly displayed in the cab. You should be aware of the effect a speed limiter will have on your vehicle, especially when overtaking.

You're responsible for the safety of the load you're carrying. At no time should the load endanger other road users. It's vital that you make sure your load is secure and safely distributed on your vehicle. How you do this will depend on the

• bulk
• weight
• type of vehicle you're driving (flat bed, curtain side, etc)
• nature of the load.

Use of the right-hand lane on motorways with three or more lanes isn't normally allowed for

• vehicles over 7.5 tonnes maximum authorised mass
• vehicles required to be fitted with a speed limiter
• vehicles towing a trailer.

This rule does not apply in special circumstances, such as when the left-hand lane is closed.

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 speed limits imposed on vehicles carrying abnormal loads can be frustrating for other drivers, but you mustn't be tempted to exceed them. Remember, the more weight you're carrying, the longer it will take you to stop safely.

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.

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

• lane closures
• incidents
• fog
• icy roads.

The type of suspension fitted to a vehicle will influence its resistance to 'roll-over'. Modern tri-axle semi-trailers fitted with single wheels on each side extend the tracking width available, making this the most stable configuration.

It's essential to know the height of your vehicle before setting off. This should be clearly marked, usually in the cab, and visible from the driving position. Look out for restrictions that you may not have seen on a map - they may be temporary.

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.

You need to know the length of your vehicle as well as its weight, height and width. Places where the length of your vehicle may be relevant are

• road tunnels
• level crossings
• ferries
• bridges.

Forward planning is important whenever you consider overtaking another road user. You should carefully assess the speed of the vehicle you intend to overtake. Remember that your vehicle's speed is limited and this could considerably increase the distance and time needed to complete the manoeuvre safely.

The driver of a passenger-carrying vehicle needs to know the vehicle's limits. These include its weight, height, width and length, and its seating and standing capacity. The unladen weight should be displayed on the nearside of the vehicle.

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.

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.

As you turn a corner, the hanging meat carcasses will all swing to one side of your vehicle, adding extra pulling force towards the outside of the curve. The faster you turn a corner, the greater this force will be. After the corner, the carcasses will continue to swing back and forth, like pendulums, making the vehicle unstable.

The long overhang at the front of a car transporter can cause problems where street furniture, such as lampposts and traffic signs, is sited close to junctions. Particular problems may be encountered when you're turning right and there are 'Keep left' bollards in the middle of the road you're turning into. Plan your route carefully to avoid such hazards.

If your vehicle touches bells suspended over the road, they'll obviously ring. This will warn you that your vehicle exceeds the safe travelling height beneath electrified overhead cables ahead. You must stop immediately and either find another route or take advice.

Look out for restrictions on long vehicles. Length restrictions are found where there isn't much room to turn (for example, in a tunnel) or where there's a risk of grounding.

If your vehicle is too long to fit into a passing place, you may need to wait opposite one. This will allow a following or approaching driver to pass. When you use this type of road, you need to plan and look well ahead to avoid meeting another road user at an inappropriate place.

As a local-service bus driver, you may use the bus lane at any time. The restrictions apply to other road users, to keep the lane clear for you at peak times. Don't be tempted to speed when driving up the inside of slow-moving or stationary traffic. Be alert for pedestrians who may be trying to cross the road.

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.

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.

In England and Wales, vehicles exceeding 7.5 tonnes maximum authorised mass are restricted to a maximum of 50 mph on single carriageway roads. In Scotland, this speed limit is 40 mph.

The railway authority needs to know immediately if one of their bridges has been hit. You'll need to tell them the number of the bridge so they can identify it. The railway authority will then take action to prevent railway passengers from being put at risk.

When you're driving a long vehicle, you'll often need to straddle lanes to turn into narrow side roads. When you do this, watch out for smaller vehicles - especially motorcycles and cycles - trying to squeeze past on your inside.

As well as a height restriction, the tunnel may have a restriction on the available width of headroom for high vehicles. The advance warning gives you the opportunity to find another route if your vehicle is too high or wide to drive through the tunnel.

The headroom under bridges in the UK is at least 5 metres (16 feet 6 inches) unless marked otherwise. However, this might refer only to the highest point of an arch. If your vehicle hits a bridge, you must report the incident to the police. If a railway bridge is involved, you must also report it to the railway authority.

The speed limit for lorries is lower in Scotland than it is in England and Wales, so be aware - especially if you drive in the border areas.

When turning at a mini-roundabout, it's unlikely that you'll be able to avoid going over the marked area. You should, however, avoid going over the roundabout where possible.

Every year, there are hundreds of incidents in the UK where vehicles hit railway or motorway bridges. Most involve buses, coaches and lorries. Make sure your route doesn't take you under a bridge that's too low for your vehicle. If you hit a bridge, you'll be putting yourself and any passengers at risk, and you could cause a major disruption to road and rail transport.

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.

A bus equipped with a speed limiter must also be fitted with a plate showing the speed setting. This must be fitted in an obvious position, where it can be clearly seen.

Some weight restrictions apply to heavy goods vehicles only and not to passenger-carrying vehicles. Look for a plate beneath a restriction sign that indicates this. Road signs show weight restrictions in various ways. You should make yourself familiar with all of them, so that you're in no doubt about their meaning and relevance.

If you see this sign, be aware that there's a danger of grounding. This can happen where there's a pronounced bump in the road, such as at a level crossing or a hump bridge.

If a height isn't shown on the bridge, the headroom (in the UK) will be at least 5 metres (16 feet 6 inches).

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.

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.