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10 Factors On Which Stopping Distance Depends: Safety Tips

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Having the right amount of stopping distance can prevent collisions, crashes, and nasty accidents. Here are 10 factors on which stopping distance depends.

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Stopping distance is the amount of space needed to bring your car to a full and safe halt. On average, this applies to the space between you and the vehicle ahead. After all, driving too close to the next car may result in a collision if the driver ahead brakes sharply or unexpectedly. If you don't have time to react and brake gradually, you'll crash.

Stopping distance should apply to all moments of driving, however. If the road is icy, for example, and you begin to skid, then you will need extra time to regain control of your vehicle before you slam into the centre divider, a ditch, or even a building.

Normally, stopping distance is a car-length between you and anything ahead. However, this space may be insufficient if you're going to fast, have poor brakes, or are dealing with other hindering factors.

Let's explore 10 factors on which stopping distance depends, and how you can create the appropriate amount of space to keep yourself (and others) safe.

1. Speed

Stopping distance is made up of thinking distance + braking distance. As such, your speed dramatically impacts your functional stopping distance. The faster you are going, then:

  • The less reaction time you will have (less thinking distance)
  • This translates into more distance travelled before applying the brake (less braking distance).

The average speed limit sits between 30-60 mph. For every additional 10 mph you are travelling, your car will take an average of 12 additional metres (or three car lengths) to come to a full stop. That's why it's crucial to observe the local speed limit and give yourself space and time to react.

2. Brakes

Anti-lock brakes help the driver maintain control of the vehicle in an emergency braking situation. However, properly maintained brakes are the real deciding factor.

As the name implies, brake pads push against the brake disc when the vehicle tries to stop. This friction wears down the pads over time, and if they are not consistently replaced, then the brake discs will press against metal instead. This not only limits the stopping power, but causes the discs to form grooves. This causes them to overheat in short order and completely lose stopping power.

As such, well-maintained brakes can help you maintain and even reduce your stopping distance. Having them regularly checked and services will keep them in good condition. This is especially important when driving on wet roads long-term, as it can lead to moisture between the pads and discs. This makes them less effective.

If you have driven through deep water, make sure to pump the brake pedal a few times while driving. This will slowly to dry them out and ensure they return to peak performance.

3. Tyre Pressure

Tyres need maximum contact with the road to ensure the best stopping distance. When tyres are over- or underinflated, then the tread has poor contact, and grip on the road is limited.

Specifically, underinflated tyres will press against the road with their outer edges, while overinflated tyres make too much contact in the centre. Both can lead to premature wear and tear, as well as damaged sidewalls, bent wheel wells, and blowouts.

In an immediate sense, the uneven traction will make your tyres less effective at biting into the road and bringing your car to a halt. Checking your tyre pressure every month and using the recommended pressure for your vehicle will ensure your tyres perform better and last longer.

4. Tyre Wear

By law, your tyres must be replaced when their tread depth reaches 1.6 mm. Even if your tyres are above this minimum, however, less tread has a massive impact on your braking distance.

Most tyres begin life with 8 mm of tread, which gradually wears down through use. As the tread reduces, so too does the tyre's ability to grip the road.

As an example, at 30 mph on a wet road, a car with brand-new tyres at 8 mm of tread will come to a stop in 25.9 metres. The same car, travelling in the same conditions, but which is fitted with tyres at 3 mm of tread, will come to a stop in 35 metres. That's 35% further, despite the tyres still being perfectly legal.

When the tyres reach the minimum of 1.6 mm of tread, their stopping distance increases to 43 metres. That's almost double the stopping distance of the new tyres. This makes it important to have them inspected by a safety expert at your local Autofusion during your normal servicing.

5. Tyre Quality

Buying premium tyres from known manufacturers, such as Michelin, Goodyear, or Pirelli, offers peace of mind that you are buying a quality product. Countless tests show that premium tyres are worth the added expense when it comes to control, grip, and stopping distance.

When travelling at 60 mph, a car fitted with premium tyres can stop as much as 16 metres shorter than a set of budget tyres. That's true even when both sets have 8 mm of tread. As a bonus, premium tyres have other proven benefits, including:

  • Increased fuel efficiency
  • Lifespan
  • Aquaplaning resistance

6. Road Conditions

Road conditions - especially those related to weather, such as rain, standing water, ice, and snow - can have a massive impact on your stopping distance. Any slippery surface will reduce friction between your tyres and the road. This has an inevitable effect on your braking.

In heavy rain, aquaplaning can occur, where the tyres cannot disperse the water between the tread and the road surface quickly enough. This results in a loss of control.

In wintery conditions, snow may become compacted in the tyre tread, which greatly reduces the traction your tyres have. If there is ice, this can lead to your vehicle skidding on top of the road and crashing.

Poor weather can increase stopping distances to 10 times greater than on a dry road. The best defence when driving in bad weather is to keep your distance, take it slow, and make sure you can maintain a clear view of the road.

7. View Of The Road

Visibility significantly impacts your thinking distance. The longer it takes for you to spot hazards in the road, the more time will have passed before you hit the brakes.

A dirty, iced-up, or cracked windscreen will hurt your view of the road. Likewise, heavy rain that isn't cleared away by your wiper blades can block your view. Make sure you top up your screen wash regularly, check that your wipers are operating correctly, clean off ice, and have any damage repaired.

8. Distractions

Keep your eyes on the road at all times. This will help you spot hazards and reduce your thinking time. Of course, it's easy to become distracted, especially in this digital age.

Avoid using your phone at all when driving, unless you have bluetooth connectivity that allows you to make and receive calls without glancing down. Programming the sat nav and playing with the radio can also be heavy distractions, so try to use voice recognition or set up any features you need prior to getting on the road.

9. Drinking/Taking Drugs While Driving

You should never drink and drive, nor take drugs while or prior to driving. Campaigns against drunk driving have been in place for decades, but since March 2015, it has become an offence to drive under the influence of certain drugs. Some penalties include a minimum 12-month driving ban, an unlimited fine (determined on a case by case basis), and up to six months in prison.

Alcohol and drugs (including cannabis and cocaine) dramatically increase the time it takes to process information. A driver under the influence may take a few extra vital seconds to spot a hazard, such as a pedestrian crossing the road, and apply the brakes. There is also evidence that a drunk/drugged driver will not press the brake pedal as hard in an emergency situation, because their senses are impaired.

10. Tiredness

As many as 1/5th of accidents on monotonous roads (like motorways) are caused by drivers falling asleep at the wheel. Even if you don't drift off, operating a vehicle while tired can severely dampen your reaction time and impair your decision-making abilities.

If you notice yourself getting tired or losing concentration while driving, find a place to stop and take a break. A 15-minute break every two hours on long journeys is recommended, alongside sharing the driving duties when possible. This will give you the best chance of staying alert and optimising your stopping distance.

To ensure you have the best stopping distance, even with uncontrollable factors, be sure to have your car regularly serviced by Autofusion. This will ensure its braking and other safety features are in peak condition, so they can bring your car to a halt just when you need it.