When brakes are applied on a car moving in a straight line, they slow the rotation of the wheels but the rest of the car tries to continue moving forward. This shifts more of the car's weight onto the front wheels, making steering more difficult. If the car is cornering when the brakes are applied, the weight shifts both forward and towards the outside of the bend, thus the weight is loaded onto one front wheel. In severe cases, this can lead to skidding or even cause the car to roll over.

A motorway number in brackets on a blue patch means that a motorway junction will be reached by following the route indicated.

Hatch markings are used to separate traffic and to protect traffic turning right. Where the boundary line is broken, you may enter the area only if necessary and provided you can see that it's safe. A continuous white line defining the hatched area means that you mustn't enter, except in an emergency. All other rules of the road apply as normal.

This sign indicates a route for trams only. Other vehicles aren't allowed to use these routes. Drivers need to look ahead and plan - especially in an unfamiliar area.

Waiting restrictions help to keep the road clear by preventing parking that will hinder the flow of traffic. Waiting restrictions on urban clearways allow vehicles to stop and pick up or set down passengers, even during their hours of operation.

Catalytic converters are exhaust-treatment systems that remove most of the harmful compounds from the exhaust gases. These include carbon monoxide, nitrogen oxides and hydrocarbons. The converter only deals with toxic, polluting gases; carbon dioxide is still produced.

Carrying a heavy load in a vehicle will change its centre of gravity. This will affect the vehicle's handling on bends, compared with when it's lightly loaded. It's your responsibility to make sure that your vehicle isn't overloaded and that any load is secure.

Strict controls on exhaust emissions require a catalytic converter to be fitted to the exhaust system of all new vehicles. Catalytic converters remove most of the carbon monoxide, oxides of nitrogen and unburned hydrocarbons from the exhaust gases.

If the steering feels light when you're driving in heavy rain, it's probably due to water that has built up between your tyres and the road surface. Easing off the accelerator should allow your tyres to displace the film of water and they should then regain their grip on the road.

If you find yourself having to stop in an emergency, it's important that your vehicle remains under control. If you lose control, you may make the situation worse. Having both hands on the wheel during braking will help you to control the steering as you stop.

In icy and snowy weather, your stopping distance will be up to 10 times further than in good, dry conditions. To reduce the risk of skidding, take extra care when braking, accelerating and changing direction.

Normally, a driver shouldn't stop or park on a road that has double white lines along the centre. However, you may stop for long enough to set down or pick up passengers, or to load or unload goods.

Exterior mirrors are designed to be convex. This gives a wide angle of view and helps to reduce blind areas. However, a vehicle behind will appear smaller and further away in a convex mirror, so it could be closer than you think.

If you see a vehicle with a flashing green beacon approaching, it means the driver or passenger is a doctor on an emergency call. Allow it to pass when you can do so safely. Someone's life could depend on the driver making good progress through the traffic.

Catalytic converters are designed to reduce toxic exhaust emissions by up to 90%. They have a high normal working temperature and for this reason are inefficient when the engine is cold.

You must stop if there's a red cross with red lights flashing above every lane on the motorway. However, if the signs over any of the other lanes don't show this signal, you may move into one of those lanes and continue, if it's safe to do so.

If it's safe to do so, you may cross a solid white line to pass a road maintenance vehicle, pedal cycle or horse, if they're travelling at 10 mph (16 km/h) or less. When safe, you may also cross the solid line to enter a side road, access a property or pass a stationary vehicle.

Reflective studs are placed along the edges and between the lanes on motorways. The colour of the stud can help you identify your position on the road when visibility is reduced; for example, when it's foggy. Between the lanes, the studs are white. Red studs are used between the left-hand edge of the carriageway and the hard shoulder. Amber studs are used along the right-hand edge of the carriageway, and green studs are used where slip roads enter or leave the motorway.

Give way to buses if you can do so safely, especially when they signal to move off from a bus stop. Look out for people who've just got off the bus, as they may try to cross the road. Don't try to accelerate past before the bus starts moving, and don't flash your headlights; other road users may be misled by this signal.

Elderly people may misjudge how far away you are and how fast you're travelling. This may cause them to step into the road when you would expect a pedestrian to wait. They may also walk slowly and so could take a long time to cross the road.