Car stopping distances explained

7th January 2022

Judging stopping distance while driving on icy roads

It’s amazing what commercial vehicles enable for UK businesses. Whether we consider HGVs transporting raw materials to enable the manufacturing of complex goods, or a taxi rank helping people reach urgent meetings and appointments on time – there’s virtually an infinite number of ways in which automobiles empower businesses to create, operate and interact.

Crucial to the usage of commercial vehicles, though, is the practice of upholding proper safety standards. After all, there’s a very real and immediate danger involved when cars are driving along a road, given it’s difficult for them to stop quickly while travelling at high speeds.

So, in this article, we’re going to explain car stopping distances and look at how commercial fleet operators can improve driver safety.

What is stopping distance?

Stopping distance is simply the time taken for a vehicle to transition from a state of moving to being at a complete stop. Understanding the physics of a car is one of the first things one learns as a beginner driver, and it’s applied every time you gently break to pause at traffic lights.

More commonly, though, we use the term stopping distance to describe the exact time needed to stop a vehicle in an emergency situation. This could be brought about, for example, by a pedestrian suddenly running out into the road, or a traffic accident. Drivers should know their stopping distances at all times to maximise safety both for themselves and those around them.

It’s also important to be aware of thinking distance. Naturally, a driver must first perceive whatever road hazard they’re facing, process it, and then choose to hit the brakes – and this is an important part of the stopping distance formula. Ideally, drivers will allow themselves adequate ‘thinking distance’ by putting distance between themselves and other drivers, and abiding by the speed limit.

How to calculate stopping distance

How, then, can stopping distance be calculated? Unfortunately, there’s no simple formula to work this out. The main components involved are to:

  1. Gauge stopping distance based on your vehicle’s speed, weight, and size. Check out our rough guide.
  2. Factor in the condition of brakes and tyres.
  3. Take into account road and weather conditions.
  4. Factor in the driver’s alertness.

Exact stopping distance will always vary from vehicle to vehicle, and stopping distance itself comprises thinking distances and braking distance elements. General stopping distances, however, are a part of modern driving theory tests and should be known by all drivers.

This is especially true for drivers of commercial fleets, and commercial fleet operators may do well to ensure firstly that drivers have an accurate understanding of stopping distances based on the vehicles they’re using (which may vary drastically for vehicles carrying heavy loads), and have the right tyres and brake technology to improve stopping distances.

Interior view of vehicle driving on motorway

Factors affecting stopping distance

In terms of closing any knowledge gaps, it’s also important to understand how the following factors can impact stopping distances.

Ice

Ice on the roads can function in a comparable way to low tyre tread; reducing the car’s grip on the road and limiting the control drivers have over their vehicles. This can seriously impact the delivery time on commercial routes, and so our tip for fleet operators would be to encourage drivers to plan their routes around roads that are likely to be well gritted and safe in the face of challenging winter driving conditions.

How much can stopping distance increase in icy conditions?

It’s estimated that icy roads could increase a vehicle’s stopping distance by up to ten times their non-icy equivalents.

Rain

Rain can impact a driver’s thinking distance by reducing visibility, thereby making it harder to spot and acknowledge hazards on the road. Poor visibility can of course be countered, to some extent, with wiper blades. But realistically, it’s very difficult to plan routes around the rain as weather can change quickly.

Consequently, fleet operators may do well to take weather conditions properly into account when assessing how efficiently drivers are planning routes – as having drivers feel pressured to rush in dangerous conditions can not only have an impact on mental health, but potentially pose a threat to physical health too.

How does rain affect stopping distance?

Braking distance approximately doubles in rainy conditions.

Tyres and brakes

The quality of a car’s tyres and brakes can drastically affect its stopping distances. Naturally, as tyre technology evolves each year, driver safety improves – and any tyres that are upward of ten years old (including spares) should be replaced immediately.

Similarly, brake pads wear down over time, and so it’s important that drivers can spot the warning signs that this may be an issue, which can include:

  • Dashboard warning lights
  • Screeching sounds
  • Grinding

Drivers could also manually check that there’s adequate brake pad remaining – with anything less than a quarter of an inch potentially proving dangerous. With tyres and brakes, it’s crucial that drivers are both aware of and adhere to legal safety limits.

Stopping distances at different speeds

We’ve already covered how different road conditions can affect braking distance, and it’s also worth considering that drivers could have a diminished thinking distance if, for example, they are suffering from fatigue or tiredness. As a rough guide, however, in perfect conditions you may find that stopping distances are roughly as follows for a medium to large-sized car with quality tyres.

Stopping Distance In Feet In Metres
Stopping distance at 70mph 315ft 96m
Stopping distance at 60mph 240ft 73m
Stopping distance at 50mph 175ft 53m
Stopping distance at 40mph 118ft 36m
Stopping distance at 30mph 75ft 23m
Stopping distance at 20mph 40ft 12m

This is based on guidance from the Highway Code, using an average vehicle length of four metres. It isn’t, however, a one-fits-all solution that can tell you the stopping distance of any vehicle, and drivers should take the external factors we’ve covered into account, as well as the weight of their load.

How to improve stopping distance

We hope this article has helped to shine a light on the importance of driver safety. Some action points to take away for commercial fleets could include:

  • Checking that your drivers have up-to-date knowledge around stopping distances, and providing them with any fresh information published by reputable authorities.
  • Auditing your fleet to ensure not only that cars are able to pass their MOTs, but that brake and tyre technology is ‘good’ rather than ‘adequate,’ which could make working for your business a more attractive prospect for job hunters.
  • Talk about driver safety internally, and equip your drivers with the right route-planning technology to make journeys safe and cost-effective.

How can Fuel Card Services help?

At Fuel Card Services, we take driver safety seriously. That’s why we offer a range of commercial fleet services that are designed to improve driver safety and provide cost savings. Services include:

  • Tele-Gence; a smart telematics system that’s tailored to your business’ unique needs. This software can improve safety for your drivers and security for your vehicles.
  • MyDriveSafe.Expert – which allows drivers to carry out vehicle checks on their mobile phones. This data then feeds back into a manager’s portal, enabling you to check that vehicles are safe to drive and that legal requirements are met.
  • MyService.Expert – we offer an online, pay-as-you-go system that gives you access to pre-negotiated repair and maintenance rates at thousands of UK garages, meaning any faults can be resolved quickly without breaking the bank.
back