Safe Speed Forums

Following on from: http://www.safespeed.org.uk/forum/viewtopic.php?t=7151

Whenever I try to look at shunts, I'm surprised to find how many of them are apparently caused by inattention rather than tailgating. I think this has to do with real world 'reaction times' in normal driving being negative. i.e. we anticipate rather than react.

There's no risk in tailgating while reaction time remains negative, but as soon as we have a bit of inattention and reaction time becomes positive, tailgating becomes dangerous and we have shunts.

Does this help make sense of the high prevalence of tailgating NOT leading to masses and masses of shunts?

_________________
Paul Smith
Our scrap speed cameras petition got over 28,000 sigs
The Safe Speed campaign demands a return to intelligent road safety

It certainly plays a part - although some of the most blatant cases I see are vans tucked in behind slow(ish)-moving high-sided lorries, to the extent that I wonder if they are hitching a ride in the slip stream.

I like to think I don't personally tailgate. Likewise, I also typically find the gap between the car in front and me increasing before an enforced slow down, dramatically so if I was also driving for the one behind me.

I think you're absolutely right.

A guy I've rallied with is a superb driver, yet on the way to events he has me permanerntly on the edge of my seat by habitually tailgating the car in front. Yet he never hits them as he's always one step ahead of them in terms of his anticipation - when they brake he's always already doing it.

If he were to rely on their braking as the trigger to start his own then he'd be shunting folk left right and centre.

I guess that is also why it feels reasonably secure to close the gap up to the car in front when preparing to overtake, as by definition at that moment our attention and anticipation is at a high.

I still don't think it's a good idea, if for no other reason than the fact that it intimidates the car in front.

_________________
CSCP Latin for beginners...
Ticketo ergo sum : I scam therefore I am!

well yes and no. The problem is the tailgater is not prepared for anything out of the ordinary. They can just about anticipate the normal flow of traffic but as soon as someone does something out of the ordinary they're toast. Just watch any busy road for a while to see the amount of heavy braking that goes on - not to mention all the plonkers violently swerving around turning cars because they can't slow down in time.

Quite.

But if we're going to make safer roads we must have a true understanding of the real-world processes.

_________________
Paul Smith
Our scrap speed cameras petition got over 28,000 sigs
The Safe Speed campaign demands a return to intelligent road safety

The (now retired) chauffer at our place of work always used to follow too close for my comfort. However, like the referred rally driver, he always stayed ahead of the game and had no accidents in seven-figure miles.

I was going to make another "against" point, in that close following must be more stressful.

But can we turn that on its head and instead theorise that perhaps it "keeps you on your toes" so you don't get distracted?

_________________
CSCP Latin for beginners...
Ticketo ergo sum : I scam therefore I am!

I think this is a "margin for error" argument. If you leave little space between you and other vehicles then the likelihood of an unexpected event leading to a crash is greater.

On sections of motorway where lanes are narrowed due to roadworks (or, come to think of it, on a normal motorway where there is a very high traffic volume) the margin of error becomes smaller. Although my level of awareness is higher ("on your toes") in these conditions, I still feel uncomfortable in much the same way as you do if someone stands too close to you and invades your personal space.

This comfort zone means that I generally hang back from the car in front more than most people.

_________________
Malcolm W.
The views expressed in this post are personal opinions and do not represent the views of Safespeed.

Perhaps it shows up how driving isn't a one size fits all thing.

When I drive I'm always working to maximise the space around me, whether laterally or "for and aft". I find this less stressful and the very act of doing it keeps me alert and "on my toes".

So this is perhaps why I feel very uncomfortable when I sit in with someone who is happy to work with less space, but this is simply their way of keeping their attention levels up.

But either way, the key common factor is Concentration. Indeed it we take the ordering of C.O.A.S.T as being as important as the content, then we can see that in both the approaches I've detailed there was no issue with the C.O.A so maybe we shouldn't worry quite so much about the S.T.!!!

_________________
CSCP Latin for beginners...
Ticketo ergo sum : I scam therefore I am!

I don't think we can take it that way. All the elements are equally important imo. It is a sequence, not a menu. A driver who is allowing insufficient space and therefore time to react can compensate by raised level of concentration, observation and anticipation. As you pointed out, that's how it is possible to safely move up to and hold the overtaking position (for a short time). However, where someone is consistently driving with very tight margins of space and time, it seems to me there's a very great probability that (like all of us) he will not sustain his C.O.A at the much higher level needed and, if something unexpected happens, he will be in trouble.

That's been my experience as well. I've only ever seen a handful of shunts caused by tailgating, and they have resulted in little more than 'fender-benders'.
On the other hand, all the truly serious shunts I've seen have been as a result of inattention - where a driver thinks that they have plenty of room in front and so start admiring the countryside. A lot of them only realise that the traffic ahead has stopped when they hear the loud bang.

_________________
Only when ideology, prejudice and dogma are set aside does the truth emerge - Kepler

I don't do it any more, but I do know how to do it, and did so for many years without incident, and perversely the skills required to do it safely are found in COAST...

Quite simply: the way the rally driver was doing it is that he was if anything looking further ahead than most drivers do and anticipating in advance. They don't have accidents because they have probably reacted before the driver in front to the slowing in traffic - but it isn't really negative reaction time unless you assume that all drivers only reacts to the actions of the vehicle immediately in front.

When driving along as a beginner you concentrate on the vehicle in front - lots. When he brakes you brake. However lots of drivers have progressed beyond that - they are looking further ahead as experience has taught them that the number one hazard in driving on the vast majority of open roads in typically heavy traffic is that the vehicles in front of you slow down quickly and you might run into the back of them. In a continuous stream of traffic (which is where tailgating occurs) you will not get children running in front of you or horses or any other hazard from the side - other than through catastrophic mechanical failure which is very rare (wheel falling off, that sort of thing).

Typically they will be watching 5 or 6 vehicles ahead or even more (10+ in heavy motorway conditions) looking for the tell-tale signs of vehicles slowing - most obviously the brake lights. When the vehicle 6 in front of you lights up, you lift off and prepare to brake, and if 3 in front does, then you start braking.

There is a down side to it - it requires complete concentration as the slightest distraction and you miss the early sign and are already too close to the vehicle in front. I expect that Mr Rally driver is very good at applying complete concentration for hours at a time.

The tailgating part however is nearly a separate issue. You do it because a) you get better view of the brake lights of the car in front of the car in front of the... if you are close then you can see through the windows of the one in front and react to what he is seeing, and b) if you leave a 2 second gap then some bugger will pull into it, and you have to slow to open a gap, and then some other bugger pulls into it, so you slow again, and again ... if you don't leave a gap then nobody pulls into it, and you effectively eliminate the risks from the sides and can concentrate to the vehicle 6 ahead.

In many ways it is advanced driving for Motorways and DCs.

One problem is that it doesn't translate well to other scenarios where the COAST rules are more at home, and some people cannot switch out of that mode when they really should have, and the other problem is that other people who don't think about driving so much, copy it without thinking by mimicking - hence two cars all alone in the middle lane of a motorway with only a cars length between them.

great theory until the car in front of you has some sort of mechanical failure or something else totally unexpected happens - like someone crossing the central reservation.

Just to play Devil's Advocate for a moment, that doesn't really defeat the theory. If some "foreign object" enters the carriageway then the idea is that you react to it at the same time as the car in front, or perhaps slightly earlier, so that you both brake at the same rate and maintain (or increase) separation.

If the "unexpected event" is something totally catastrophic, such as a notional twenty ton weight dropping from the sky immediately in front of the car you are tailgating and causing sudden and massive deceleration then you would still hit it if you were two seconds behind - in fact you'd hit it harder as a bigger speed differential would have had time to develop.

Going back to the original post, I've been thinking a bit about this and I have to say I agree with Paul. I can think of a few occasions over the years where I've come close to embedding myself in the back of the car in front, and in each case it has been due either to a lapse in concentration or to being distracted from looking ahead.

And to pick up on the other point about C.O.A.S.T. I think it does work very well as a prioritised list. Look at it in terms of which deficits are most likely to lead to crashes? Loss of Concentration is clearly top of the list, as all of the others are dependent on it. Loss of Observation would be next most likely to cause a crash (eg didn't see child run out), which in turn is more likely to cause an accident than a lapse of anticipation (failed to expect child to run out). And so on...

_________________
CSCP Latin for beginners...
Ticketo ergo sum : I scam therefore I am!

and as we all lose concentration or get distracted on the odd occasion, might this not be a very good reason for actually leaving a gap rather than presuming that you're so brilliant you can sit safely on the bumper of the car in front? Building that tolerance into my driving has saved my bacon a couple of times.

Whoa there! Just hang on a minute...

Go back and read my earlier posts - I never said I advocate this style of driving, in fact quite the opposite.

I'm pursuing this as a theoretical debate into the logic behind why people like my friend seem able to drive in this style for decades without ever crashing.

Indeed, both you and I - with our more relaxed style - now admit to having occasional lapses of concentration that only our longer gaps have saved. Could it be that we are the ones in error?

So in true "brainstorming" style can we look at this the other way round:

Does the accident free tailgater drive that way because he has better concentration, observation and anticipation, or does he have better concentration because he follows people more closely?

_________________
CSCP Latin for beginners...
Ticketo ergo sum : I scam therefore I am!

It's quite scary this. So much that we think we know (national 'we') is wrong, or at least incomplete.

_________________
Paul Smith
Our scrap speed cameras petition got over 28,000 sigs
The Safe Speed campaign demands a return to intelligent road safety

To complete the loop on my earlier musings, where (like Johnsher and I suspect many others) I can recall a number of occasions where I have nearly shunted the car in front due to a lapse of concentration / observation, this has always been where I have been following at a "safe" distance.

But is this a fact that I should perhaps be drawing the opposite conclusion from? Instead of seeing this as disaster averted by leaving a long gap, should I see it as concentration loss due to leaving a long gap?

Can we theorise that there is an inverse relationship between following distance and concentration level? If so then what is the optimum distance? If we tend to find ourselves having occasional losses of concentration should this be a trigger to us to follow a bit closer rather than a bit further away?

Interesting stuff...

_________________
CSCP Latin for beginners...
Ticketo ergo sum : I scam therefore I am!

This is the most interesting part to me right now. When I drive and when I observe driving mostly I don't see 'reacting' at all. I especially don't see panic reactions with any regularity. Mostly traffic flows pretty well with most folk understanding what other folk are going to do.

This of course is normal driving with a good dose of experienced drivers' anticipation. And if 'anticipation' isn't negative reaction time I don't know what it is.

Yet road safety policy assumes that drivers only react, and fail to react fast enough.

_________________
Paul Smith
Our scrap speed cameras petition got over 28,000 sigs
The Safe Speed campaign demands a return to intelligent road safety

Our "near miss" shunt demonstrates this perfectly. Lose concentration and we lose anticipation - this is the very situation where we really do "react" rather than anticipate, and when we drive in this mode suddenly our two second gap is only barely enough to avert a crash.

Whereas when our anticipation is at its highest - lets say when we are following at 1 second gap preparatory to overtaking - we don't feel even slightly uncomfortable coping with anything that goes on in front and causes the car in front to slow (or whatever).

_________________
CSCP Latin for beginners...
Ticketo ergo sum : I scam therefore I am!