A motorway with a few cars driving down it towards a roundabout.

Rumble device: What is it and how does it work?

One of the most effective traffic calming measures.
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  • They are a safety feature of the road that alerts drivers to the presence of incoming junctions, roundabouts, or other high risk of accident parts of the road.
  • Rumble device appears most commonly as rumble strips which, provide a visual, audible and tactile feedback when driving over them.
  • If you hear, feel or see them, you must reduce your speed in good time to avoid causing an accident.

Are you a learner driver looking for more information about rumble devices? Or perhaps you're just a curious driver. It pays off to understand all the different safety features of the road are.

What is a rumble device?

A rumble device alerts drivers to a hazard by providing both a visual and audible signal as well as through vibration which can be felt in the car and steering wheel.

These are usually rumble strips, which cause your car to vibrate as you drive over them.

Rumble strips are meant to provide a tactile warning before a junction, roundabout or bend in the road so that drivers can reduce their speed in good time.

Most commonly, the rumble device is a long series of raised lines on the road, which can really help drivers at night when visibility is limited.

What is a rumble device used for?

In basic terms, they are used to alert drivers of any incoming hazards. The vibration can't be easily ignored that's why rumble strips are very effective at helping drivers who might not be paying close attention to their surroundings.

Rumble strips usually appear on roads in groups. The number of rumble strips in a group and the distance between groups depend on road conditions. Usually, there are 2 to 5 strips in a group.

According to the Highway Code, they are designed:

  • to be seen
  • to be heard
  • to be felt

There are three main types of rumble device:

  • Shoulder rumble strips - these exist on the shoulders of the roads, on the outer sides of the lane. They exist to reduce risk of driving off the main carriageway.
  • Transverse rumble strips - sometimes referred to as bar markings or rumble wave surfacing, they stretch across the whole of the carriageway before roundabouts, junction, or in traffic-calming areas.
  • Centre line rumble strips -  A series that runs down the centre line and drivers when the cross it. It's there to prevent entering incoming traffic.
Road rumble device strips on one side of the road in the UK.

Do rumble strips reduce speed?

The rumble device can only communicate to drivers that they need to slow down. They are not a substitute for good driving. It cannot make up for bad speed limits, poor road design and traffic management, or the lack of enforcement in an area.

Rumble device is meant to reduce risk of an accident and help drivers be aware of the road ahead and any incoming, potentially, dangerous parts of the carriageway.

If you're wondering how effective they are, there hasn't been a lot of research aimed at this here in the UK. However, according to a study by the North Dakota Department of Transportation, during the trial period they saw a 33% decrease of frequency of crashes.

The fact is that rumblers are effective at slowing down vehicles on highways and other busy roads where traffic flow speeds tend to be faster. The faster the speed, the louder the noise and the stronger the vibrations of the car would be.

The rumble device and the driving theory test

If you studying for your theory test, you should be prepared to know what the rumble device is, how it works, and what its purpose is. Remember, you while you can take your test in an automatic car (you can even do so in an EV!), you may want to consider learning on a manual so you can drive a wider range of cars in the future!

The usual questions you may encounter in the test include:

  • What’s a rumble device designed to do?
  • What should you do when you see, hear, or feel a rumble device?
  • Where are you most likely to see a rumble device?

If you've read this guide, you'd (hopefully) know the answers to the above questions! :)

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