When Should You Use Hazard Warning Lights?

Hazard warning lights or hazard warning lamps are flashing amber lights that can be found on all corners of your vehicle. They're usually activated when a driver pushes a red triangle button, which is located on the vehicle's dashboard. Unlike your normal directional indicator lights, which flash on either side of your car to inform other drivers that you intend to turn or switch lanes, hazard lights flash on both sides simultaneously to create a visible warning signal.

Hazard lights aren't designed to communicate your intention to move or head off in a certain direction; they serve as a way to alert other road users and warn drivers that there may be a hazard ahead, or something unusual or unexpected is happening. They serve as a universal emergency signal, helping drivers recognise potential danger and respond more quickly to sudden changes on the road.

You shouldn't use your hazard warning lights unnecessarily. Their primary use is for alerting drivers about potential hazards, and there are a few specific situations where you may need to use them. For instance, they can be used when your car is stationary and temporarily obstructing traffic. When driving, hazard lights should only be used on a motorway or dual carriageway to alert others to a hazard or obstruction ahead.

Here are some specific circumstances that may call for you to use your hazard warning lights.

When you are forced to unexpectedly slow down

If you're driving on a motorway or a dual carriageway, traffic can come to a halt quickly. If you're forced to brake harshly, turning on your hazard warning lights can warn drivers behind you that traffic is coming to a standstill and they can react accordingly.

If your vehicle is temporarily obstructing traffic

You may need to stop briefly due to an obstruction, engine problems, or debris on the road.  In cases like these, switching on your warning lights tells other drivers that your vehicle is in an unusual position and that they should proceed with caution.

To warn drivers of an accident or obstruction ahead

If there’s been an accident, a breakdown, or an unexpected obstruction, hazard lights alert other drivers behind you that they may need to slow down. Once you've passed the area safely, drivers must remember to switch the warning lights off immediately.

Drivers should always remember that hazard lights should only be used in exceptional circumstances and not as a casual signal.

Yes. Breaking down in your car is certainly a stressful experience, but if your vehicle has come to a standstill in a busy or unsafe location, keeping yourself and other road users safe is a priority. In these situations, using your hazard warning lights is essential as they'll make your car more visible to other drivers who can react accordingly. Even from a distance, the flashing amber lights on your vehicle will draw attention to the situation and warn other drivers that something is wrong.

If you've managed to pull into a lay-by, the hard shoulder of a motorway, or a bus stop, using your hazards can ensure other drivers exercise caution. You should keep your hazard lights on whilst you're waiting for help or roadside assistance. This approach highlights the situation to other drivers, and also means that a recovery vehicle will spot you a lot quicker!

The use of hazard warning lights in poor weather conditions can leave many drivers confused. If visibility drops, then switching them on can seem like a logical choice. In the UK, you should not use hazard lights while driving in poor weather. Instead, use dipped headlights or fog lights if visibility is seriously reduced. Hazards may only be used if you are stationary and your vehicle is a potential obstruction. However, they still have a very specific role and should be used in certain circumstances.

For example, suppose you're forced to stop because of extreme weather, such as a snowstorm or thick fog, and your car is stationary or potentially causing an obstruction. In that case, you should use your hazard warning lights to warn other vehicles that you are not moving. This prevents other drivers from colliding with you. Using your warning lights whilst still moving can cause confusion, so only use them if you're stationary.

It's a common grey area, and sadly, because of the lack of clarity, it's the most common way drivers end up using hazard lights inappropriately. While you can use your hazard warning lights when your vehicle is stationary, there are rules about when this is acceptable and when it isn't.

Acceptable in limited parking situations

In the UK, you may only use hazard lights while parked if your vehicle is temporarily obstructing traffic and poses a risk to other drivers. For example, if you’ve had to stop because of a breakdown, or you’ve pulled over in a place where your vehicle could cause danger. Even then, your stop should be as brief as possible, and you must ensure you’re not blocking crossings, emergency access, or causing unnecessary obstruction.

Used to justify bad parking

If you're double-parked or stopping on yellow lines, using your hazards does not make dangerous or illegal parking acceptable. Whether you're just stopping outside a shop, parking on the pavement, or blocking a junction, using your hazard warning lights does not excuse this, and you could be fined or even receive penalty points if caught. You should only use your hazard lights if you're posing a risk to other road users.

Hazard warning lights are essential for alerting other drivers to potential hazards on the road. Misusing them can cause confusion and increase the risk of accidents. Here's when you shouldn't be using them:

• As a routine signal
• To claim a parking space
• To justify illegal parking or override parking laws
• When towing another vehicle
• To signal impatience or even thanks to other drivers
• When moving slowly on a busy road (except on a motorway or dual carriageway if you need to warn drivers of an unexpected hazard or obstruction ahead).
• When waiting in a traffic jam or at traffic lights

Why is it dangerous to misuse hazard warning lights?

Using hazard lights inappropriately can make them less effective in genuine emergencies. This can lead to miscommunications between drivers and increase the risk of rear-end collisions or sudden braking. Using them responsibly and accurately means that other drivers can quickly understand if there's danger ahead.