I noticed on one forum someone has asked if it is OK for the ABS to kick in when you do the emergency stop on your test (and, I would imagine, in real life). Typically, opinions fall into two diametrically opposed camps.
It’s worth quoting what DT1 – the DSA’s Internal Guidance Document – has to say about the subject:
ABS – Anti-lock braking system.
Note: Anti-lock braking systems (ABS) are being fitted to an increasing number of vehicles. Examiners should not enquire if a vehicle presented for a test is fitted with ABS.
Most ABS systems require the clutch and footbrake to be depressed harshly at the same time to brake in an emergency situation; therefore a fault should not be recorded purely for using this technique with a vehicle fitted with ABS on the emergency stop exercise. Further advice regarding ABS is given in the DSA publication ‘driving the essential skills’.. On the emergency stop exercise, under severe braking, tyre or other noise may be heard, this does not necessarily mean the wheels have locked and are skidding . Examiners should bear these points in mind when assessing the candidate’s control during this exercise
Now take a look in Driving: The Essential Skills (TES) and look at what it says concerning ABS systems:
…You should refer to the owner’s handbook for details of the manufacturer’s recommended method of use…
More on what TES says about emergency braking later. Let’s take a look at some typical (and common) owner’s handbooks first.
Vauxhall Corsa
For optimum braking, keep the brake pedal fully depressed throughout the braking process, despite the fact that the pedal is pulsating. Do not reduce the pressure on the pedal.
Do not let this special safety feature tempt you into taking risks when driving.
Traffic safety can only be achieved by adopting a responsible driving style.
Vauxhall Astra
Antilock brake system (ABS) prevents the wheels from locking.
ABS starts to regulate brake pressure as soon as a wheel shows a tendency to lock. The vehicle remains steerable, even during hard braking.
ABS control is made apparent through a pulse in the brake pedal and the noise of the regulation process.
For optimum braking, keep the brake pedal fully depressed throughout the braking process, despite the fact that the pedal is pulsating. Do not reduce the pressure on the pedal.
Ford Focus
Using ABS
When hard braking is required, apply continuous force on the brake pedal. Do not pump the brake pedal since this will reduce the effectiveness of the ABS and will increase your vehicle’s stopping distance. The ABS will be activated immediately, allowing you to retain steering control during hard braking and on slippery surfaces. However, the ABS does not decrease stopping distance.
Ford Fiesta
Using ABS
When hard braking is required, apply continuous force on the brake pedal. Do not pump the brake pedal since this will reduce the effectiveness of the ABS and will increase your vehicle’s stopping distance. The ABS will be activated immediately, allowing you to retain steering control during hard braking and on slippery surfaces. However, the ABS does not decrease stopping distance.
I’m sure if you looked hard enough you’d be able to find one manufacturer or one model or another who says to do it differently. But there is an obvious trend here, and few seem to advise anything particularly unusual.
The message is quite clear: LET ABS DO THE WORK, AND DON’T TRY TO OVERRIDE IT.
Of course, there are those for whom obfuscation and the pointless pedantry associated with explaining that you “must be in control” is lifeblood. And let’s not forget the issue of braking and declutching at the same time to add to any obfuscation.
I doubt that many driving instructors are unaware of the need to remain in control, but it doesn’t stop others pointlessly trying to explain nonetheless.
Ironically, I the question was probably being asked with a deliberate hint that those instructors who teach that the ABS should do the work were wrong. In actual fact, it is fortunate for such people that the DSA’s examiners don’t play it by the book, because it would appear that those who teach that the ABS shouldn’t kick in are probably closer to being wrong about it.
Examiners – and anyone facing down a pratmobile hurtling towards them – just want to see a controlled stop. If that’s what they get then it’s a case of job done.
Whether the ABS kicks in or not is down to many factors. A controlled stop that won’t engage the ABS in dry conditions on a clean and level surface will almost certainly engage it in the wet on a slight declination. Even on the flat, a bit of dust or gravel will change the physics completely. And on snow or ice, the ABS will kick in as soon as you touch the brake whether you want it to or not. It’s up to the examiner at the time to decide if the stop was prompt enough to be labelled as satisfactory.
If the test candidate stamps on the brake with all their might, causes the examiner to head butt the roof, and scuds to a halt over less than a metre from speed of 30mph, then the examiner just might not consider it to be “controlled”. Not many people need to keep being told this.
TES goes into more detail after having advised checking the car’s owner’s manual. It deals with the issue on the premise that the ABS should be allowed to do the work.
How do you do the emergency stop?
At the prompt (when the examiner says “STOP” and raises his hand; or when in real life – for example – that woman with the pushchair walks out in front of you):
- brake firmly and progressively (i.e. apply more and more pressure) to stop in the shortest distance safely
- just before you stop, put the clutch down
- keep your bloody hands on the steering wheel up to this point!
- once you’ve stopped, apply the handbrake and put it in neutral
- take a look around and rest your feet
In reality, you’ll brake hard and declutch very soon afterwards – almost (but not quite) simultaneously. There’s no messing about with stopwatches and stuff! You just do it. But what things are classed as potentially serious faults during the stop?
- responding too slowly
- putting the clutch down before the brake
- putting the handbrake on before you’ve stopped
- skidding out of control
- missing the brake pedal
- taking your hands off the steering wheel
Notice how “stalling” isn’t on there. As long as you put the handbrake on and put it in neutral if you stall, then restart the engine, you shouldn’t worry – but obviously, don’t stall deliberately. Learn to do it properly.
Putting the clutch down too soon can cause the car to surge forward, then forces the brakes to do all the work. This results in longer stopping distances. Make sure your method allows the brakes to engage before the clutch is disengaged.
When moving off – when told to do so by the examiner – get it in gear, get ready, and look all around. That’s over BOTH SHOULDERS and the mirrors. You can fail for not looking around properly before driving away.
Just to summarise one more time, though:
- when that woman with the baby in the pushchair walks out in front of you after you pass your test, you will hit the brakes as hard as possible to avoid hitting her
- you won’t give a flying toss whether the ABS kicks in or not – because you don’t need to
- you want to stop over the shortest distance, so don’t put the clutch down before the brake
- on your test, the examiner wants to see you demonstrate this simple skill by stopping quickly and in control when he tells you to
- there is a big difference between doing it on test and doing in real life (e.g. to avoid the woman with the pushchair)
- if your car has ABS, it is there to help you. Let it!
- the DSA says you should do it this way
- your vehicle handbook almost certainly says to do it this way (check!)
- if someone is telling you otherwise, they are telling you wrong
Does ABS kick in if you hit the brake hard?
Not automatically – or rather, not as an immediate result of hitting the brake pedal. ABS kicks in when the wheels are locked, and allows them to move slightly. By hitting the brakes hard, if the wheels lock – and the car starts to skid – then ABS will kick in. However, if you hit the brakes just as hard and the car stops without skidding then the ABS will not kick in.
It is locked wheels which trigger the ABS, not the act of braking by itself.
Should I put the clutch down at the same time as the brake?
The blog has been getting hits from www.pistonheads.com (hi guys) as a result of a thread asking precisely this. As the DSA guidelines say, doing so is not automatically a fault – but it depends on the car and the manufacturer’s recommendations.
To be honest, I haven’t found a handbook which says the clutch and brake “should be depressed simultaneously”. I’m not saying there aren’t cars in which the handbook does say this, but most appear not to. So you’re going to have to apply common sense over stopping in an emergency.
What does common sense say? Well, if you put the clutch down first, the car will surge forward – especially downhill – and the brakes will subsequently have to do all the work (and a lot more of it!). At the very least, you’ll stop over a longer distance, and that is no good for the woman with the pushchair you were reacting to. We can easily say that you must not de-clutch first.
If you hit the clutch and brake at exactly the same time it is highly likely that you will release the clutch plates before the brakes have started to grip significantly – and it will vary from car to car depending on clutch wear and pedal adjustment. In a panic situation this could easily lead to a longer stop.
So, common sense would suggest that you brake first, and then de-clutch (as per the advice in TES). This makes sure the brakes are starting to act before engine braking is lost by separating the clutch plates. Unless your vehicle handbook says otherwise, leave de-clutching for as long as possible to increase the amount of engine braking available during the braking phase.
Driving shouldn’t be over-complicated. If you have to stop, then stop. Don’t get into a debate over it.
The simple solution as far as training new drivers goes is to teach them to brake firmly, then put the clutch down. During an actual stop the two operations happen so quickly that they are virtually simultaneous anyway – but not so simultaneous that de-clutching affects the braking operation.
As long as the brakes have purchase, de-clutching will not attract a fault from an examiner if a satisfactory controlled stop is effected.
Do you fail if the ABS kicks in?
No. The DSA doesn’t say that anywhere. They will not fail someone just because the ABS engages during a controlled stop.
Do learners find the emergency stop difficult when taught “the DSA way”?
No. To start with, there is no “DSA way”. It makes perfect sense to brake first then de-clutch a fraction of a second later, and it’s the easiest thing in the world for most people to learn. TES is simply highlighting the best way.. The only ones who have problems with it are those with existing habits, and who are perhaps unable to accept they are wrong.
Why not teach people to brake and de-clutch at the same time?
The method in TES says to brake first and de-clutch later. As long as this doesn’t go against the manufacturer’s recommendations (as the DSA correctly points out) then it is the best method. There is absolutely nothing wrong with the method outlined in TES.
The biggest danger of simultaneous pedal-dipping is that the clutch gets released before the brakes take hold. Obviously, this is extremely dangerous to the point of being potentially fatal if it causes you to stop over a longer distance.
How do you engage the ABS in an emergency stop?
The ABS is something that engages when it needs to. You don’t set out to make it operate. It will kick in if the wheels start to lock making it possible to maintain some steering control during the stop. When stopping in an emergency you just brake as hard as you need to and if that causes the ABS to kick in then you just let it do its job.
The driving test only tests stopping in a straight line, but that’s not like the real world.
So what? The driving test emergency stop is making sure you can hit the brakes hard enough to stop, and do it in such a way that you stop in the shortest distance. It’s not testing you on every imaginable situation. In any case, you really do want to avoid having to do a real emergency stop on a bend because it’s bloody dangerous.
The bottom line is that if someone runs out just in front of you you’re going to hit the brakes and try as hard as possible to not hit them. On a bend, the risk of spinning off the road when braking hard is extremely high. There’s nothing anyone can do about that – it’s the laws of physics. The same is true if someone flings the wheel to try and avoid something.
Someone once said to me “you can’t test what would happen if someone let off a bomb by letting one off yourself – you have to simulate it”. Exactly the same applies to the emergency stop.
The DSA is deliberately vague about how to do an emergency stop.
Nonsense. TES has two full pages of information about stopping in an emergency covering defensive driving and avoidance, ABS, and the basic routine itself. What exactly do you expect them to say?
If you’re an ADI taking this approach you can’t blame your lack of knowledge on TES not going into the exact detail that you want. If you want more you can easily find it on the internet.
What happens when the ABS kicks in?
Once the electronics under the bonnet detect the wheels have locked (i.e. that you’re skidding), they will release-brake-release very rapidly for you. The footbrake pedal will vibrate and you may hear a noise that sounds like you’re skidding on gravel. Just let the ABS do its job and don’t release the pressure on the brake (unless it is to help you recover from a serious skid, where the car is starting to swing out dangerously).