Understanding the proper use of hazard warning lights

What are hazard warning lights?

Hazard warning lights are flashing indicator lights that warn drivers of your presence or to alert them of a hazard ahead. When activated, all four indicators, front and back, will flash intermittently at the same time to indicate a hazard – more modern cars often sometimes feature additional lights on the door mirrors or front wings. They also use exactly the same bulbs as your indicators, meaning they flash the same colour – orange or amber.

Hazard lights were first developed in 1951 and as an aftermarket accessory. They became a requirement and all new vehicles were to be equipped with them by the late 1960’s. These new regulations came into place around the world and they became a standard in the motor industry.

Developed to alert other road users of potential hazards on the road, a 2013 study explored the effectiveness of flashing bake and hazard systems found that flashing amber lights reduced brake response time by 10% compared with red lamps.^[1]

Results showed that flashing amber lamps reduced drivers' brake response times significantly by 0.11s (10%) on average compared with red lamps.

How to turn on hazard lights

They are usually operated by pressing a large, red triangle button on your vehicle’s dashboard. If driving, press the button once and wait approximately five seconds before turning them off. In the event of a breakdown, you should leave your hazard lights on until you either drive away or get towed.

How can you tell your hazard lights are on?

When you activate your hazard lights, your indicators on the inside of your car will flash too – i.e., those little green arrows. You’ll also hear that recognisable ticking sound.

Are hazard lights a legal requirement?

Hazard warning lights are used to warn drivers of your presence or to warn them of a hazard ahead. All cars built after 1st April 1986 are required to have them by law. As stated in the MOT Inspection Manual from the Driver and Vehicle Standards Agency, ‘hazard warning lamps must operate using only one switch and with the engine or ignition switch in both the on and off positions’.

Vehicles first used before April 1986 do not need to have hazard warning lights. They are also not required on vehicles that:

• Do not have front and rear position lamps (lights)
• Have front and rear position lamps that are permanently disconnected, painted over or masked.
• Were first used before 1st January 1936.

On top of this, tricycles and quadricycles classed as mopeds do not need hazard warning lamps. Only ‘bodied’ mopeds must have direction indicators.

When are you allowed to use hazard lights?

The Department of Transport are clear on when you should and shouldn’t use your hazard lights.

According to the Highway Code, you should only use them when your vehicle presents a potential hazard to other road users – or if you’re alerting other road users to another hazard on the road.

The Highway Code states, ‘they may be used when your vehicle is stationary, to warn that it is temporarily obstructing traffic. Never use them as an excuse for dangerous or illegal parking. You MUST NOT use hazard warning lights while driving or being towed unless you are on a motorway or unrestricted dual carriageway, and you need to warn drivers behind you of a hazard or obstruction ahead. Only use them for long enough to ensure that your warning has been observed.’

Some examples of situations when you may use your hazard warning lights include:

• Obstructing traffic or pedestrians – you have stopped in a place that obstructs the path of other vehicles or pedestrians, maybe due to a breakdown or to make way for an emergency vehicle.
• Warning drivers of an upcoming hazard – you can use your hazard lights while moving if on a motorway or dual carriageway and there is an obstruction that other drivers behind should be warned about.
• Emergency stopping lane – if you stop in an emergency stopping lane on a motorway or dual carriageway, you should use your hazard lights to signal to emergency services that you need assistance.
• Slow-moving vehicle – you may be driving slowly and obstructing other road users, for example, you might be driving a vehicle like a tractor that is legally entitled to be on the road but unable to keep up with the regular traffic flow.
• Specialist vehicles – some specialist vehicles, like ice cream vans, might use their hazard lights in certain situations, such as to stop to sell ice cream.

As a general rule, you should only use your hazard warning lights if your vehicle is stationary, unless in the circumstances outlined above. If you have broken down or obstructing a road, you should only turn off your warning lights if you no longer pose a hazard to other road users.

On the other hand, if you do happen to be on the move, you should only keep them on long enough to be noticeable – usually five seconds is enough. It’s also important to remember that when you use your hazard lights, your indicators won’t work simultaneously. If you’re using them and still on the move, you should disable the hazard lights before making a turn.

When can you use your hazard warning lights on a motorway?

As mentioned above, you should only use your hazard lights on a motorway in the following circumstances:

• You have broken down or stopped for an emergency in the hard shoulder. You should keep your lights on to alert emergency services that you need assistance and only turn them off when your car is no longer a hazard.
• You want to alert fast-moving drivers behind you of upcoming stationary traffic or a hazard – allowing them to slow down in time and prevent a collision.
• You are being towed and you want to warn other motorists of an upcoming hazard as the towing vehicle’s lights are not visible.

What should you do in a breakdown?

You’re most likely to use your hazard lights if you break down. If you feel your car starting to lose power, you should put your hazards on to warn drivers that you may be about slow down and stop. This will allow other drivers to keep their distance and avoid a collision. If your car does break down on the road, put your hazard lights on to warn other drivers that you are obstructing the road – even if in full daylight. If you find yourself on a dual carriageway or motorway, you should stop on the hard shoulder and stick those lights on. Make sure you don’t turn them off until your car is no longer a hazard to other road users or being towed.

Do you still need to use a warning triangle?

While warning triangles are not a legal requirement in the UK, it is advised you keep one in your vehicle as an additional safety precaution. These are another method of alerting drivers of potential hazards, keeping you and your passengers safe by giving them plenty of time to slow down and prepare. If you are unfortunate enough to experience a breakdown or accident, find a safe place to stop and put on your hazard warning lights. The driver and passengers should then leave the vehicle and stand in a place that’s not likely to create additional risk.

According to the Highway Code, ‘if you break down on a carriageway, you should put a warning triangle on the road at least 45 metres (147 feet) behind your broken down vehicle on the same side of the road.’

A total of 45 metres works out at about 60 steps for the average adult. Make sure the triangle is clearly visible to other drivers and take care when leaving and retrieving it from the side of the road.

Please note: according to the Highway Code, you should never use a warning triangle on a motorway, as it can obstruct the hard shoulder. If you have to stop, make sure you use your hazard warning lights to alert other drivers.

Can you use your hazard lights when being towed?

As mentioned previously, The Highway Code provides clear guidance on this, stating: ‘You MUST NOT use hazard warning lights while driving or being towed unless you are on a motorway or unrestricted dual carriageway and you need to warn drivers behind you of a hazard or obstruction ahead.’

When should you not use your hazard lights?

Knowingly or unknowingly, many drivers often take liberties with their hazard lights – so it’s important to know what isn’t allowed to keep you on the right side of the law.

You should avoid using them in the following situations:

• Quick stops – we’ve all been there. You want to make a quick stop to pick something up or drop someone off and you can’t find a parking space. However, hazard lights don’t override parking laws and you might end up with a fine or even points on your licence if you’re caught doing this. There must be a genuine reason for causing an obstruction.
• Substitution for headlights – remember, hazard lights aren’t a substitute for headlights if you’re driving in the dark. If your headlights aren’t working, you should avoid driving until they’re repaired.
• Choosing to drive slowly – if you’re lost or trying to find your way, it’s better to pull over and get your bearings rather than obstructing other drivers by driving slowly.
• Flashing drivers to thank them – you shouldn’t flash your hazard lights to thank other drivers as this could be misinterpreted and cause confusion.
• Being towed – when your vehicle is being towed, your hazard lights aren’t required, unless you want to warn drivers behind of an obstruction and the towing vehicle’s lights aren’t visible.

Is it illegal to drive with your hazard lights on?

There is no set penalty or fine for wrongly driving with your hazard lights on, but it could lead you to being charged with a separate offence if you cause confusion on the road.

If you drive with your hazard lights on and it causes an accident, you could be charged with driving without due care and attention (or careless driving), which could see you fined £100 and receive three penalty points.

If it was to go to court, careless driving carries a maximum £2,500 fine and nine points – but it’s highly unlikely a hazard light offence would go that far.

Neil Greig, IAM RoadSmart Director of Policy and Research, said in 2019: “According to Rule 116 in the Highway Code, hazard warning lights may be used when your vehicle is stationary to warn that it is temporarily obstructing traffic. “It is a grey area because you can use them when moving to alert other traffic to a hazard ahead and they don’t define ‘only use them long enough to ensure that your warning has been observed’, so our advice would be to use them sensibly and for the police to be as flexible as possible in enforcing the regulations.”

References

1. Guofa Li, Wenjun Wang, Shengbo Eben Li, Bo Cheng and Paul Green
   (2014) Effectiveness of Flashing Brake and Hazard Systems inAvoiding Rear-End Crashes
   https://www.researchgate.net/publication/273180474_Effectiveness_of_Flashing_Brake_and_Hazard_Systems_in_Avoiding_Rear-End_Crashes