2 second rule on motorways

On Mon, 13 Feb 2012 16:19:44 -0800 (PST), Tony Haynes
wrote:

On Feb 13, 10:36*pm, Alex Heney wrote:
On Mon, 13 Feb 2012 05:41:05 -0000, Skipweasel
wrote:





In article ef05ab79-903e-4783-87eb-
,
says...
I've just watched a piece in iPlayer where a motorist bounced off the
central barrier, risking the lives of all around him, *just after
joining a motorway. His excuse? He hit lying water at 75mph and lost
it. "But at motorway speeds in the fast lane that you've just joined
you don't have a chance to react," he said.

Then bloody slow down, especially in rain, and when joining a motorway
don't jump straight into the overtaking lanes, you pillock!

Depending on the circumstances, he might just have a point.

If the traffic on the motorway is travelling at that speed, then that's
the speed at which you have to travel /to get on/.

I'm not aware of any motorways in the Uk where you join from a
non-motorway directly into the outside lane (wrongly described as the
"fast lane" by the pillock above).


This pillock did, straight across two lanes of slower moving traffic
into the outside lane that he could not see to be clear. It wasn't.

The problem with the 2 second rolling gap theory is, at speed, in
multiple shunts, that gap rapidly decreases and the car in front could
almost suddenly stop dead. You won't.... or will... as the case may
be. In bad weather especially the gap should be far greater. If you
don't think so then perhaps you should give up your licence?


Why do you believe I might not think so?

Every copy of the "2 second rule" I have seen has emphasised that
part.
--
Alex Heney, Global Villager
3 kinds of people: those who can count & those who can't.
To reply by email, my address is alexDOTheneyATgmailDOTcom

On Tue, 14 Feb 2012 09:46:05 -0000, R C Nesbit wrote:

Tony Haynes spoke:
The problem with the 2 second rolling gap theory is, at speed, in
multiple shunts, that gap rapidly decreases and the car in front could
almost suddenly stop dead. You won't.... or will... as the case may
be. In bad weather especially the gap should be far greater. If you
don't think so then perhaps you should give up your licence?

Unfortunately most drivers simply drive and observe to the car in front
rather than beyond as far as possible.


Indeed.

In many circumstances I've seen a problem develop several furlongs ahead
and started to slow (without brakes) and drivers behind tend to get
aggravated.


Last year, on the way up to Scotland, I was involved in such a
situation.

I was in a very dense, quite slow moving line of traffic passing the
results of a minor accident that was on the hard shoulder (with police
in attendance), Because I *was* looking further ahead, I saw something
"puff out" from ahead towards the central reservation , and had my
brakes on before the car in front of me. He was the in fact still
quick enough to be the first not to hit the one in front. It finished
up with SEVEN cars all piled into one another, and we hadn't been
doing more than about 40 to start with.

I suspect most of them hadn't even been looking one car ahead, but had
been rubbernecking the scene on the hard shoulder.
--
Alex Heney, Global Villager
Double your drive space - delete Windows!
To reply by email, my address is alexDOTheneyATgmailDOTcom

On Tue, 14 Feb 2012 10:29:40 -0000, R C Nesbit wrote:

Nightjar spoke:
I think that, when they had to find a replacement for asbestos in brake
pads and shoes, they actually ended up with something that wore much better.

But the brake disks are now 'consumables'

Yes.

Modern brake discs only seem to last through about two sets of pads.
--
Alex Heney, Global Villager
Oxymoron: Weather Forecast.
To reply by email, my address is alexDOTheneyATgmailDOTcom

On Tue, 14 Feb 2012 09:07:22 +0000, Nightjar
wrote:

On 14/02/2012 07:36, Doug wrote:
On Feb 13, 9:30 am,
wrote:
On 13/02/2012 06:20, Doug wrote:









On Feb 13, 2:26 am,
wrote:
On 13/02/2012 00:40, Mr. Bean wrote:

I feel that that at 70mph, the 2 sec rule between cars is an inadequate
time to avoid a pile up.I would say more like 4 secs.

Two seconds is a pessimistic estimate of the perception and reaction
time of the average driver and is intended to ensure that you don't
drive into the back of the vehicle in front before you realise it is
doing something other than continuing along the road at the same speed.
It is not intended as a stopping distance, which would actually be close
to a three second gap, using the Highway Code's average stopping
distance table (stopping distance from 70mph = 315 feet : 70mph = 102
feet per second).

If you prefer a larger gap, there is nothing to stop you leaving one.

Except when your gap is taken by another impatient and dangerous
motorist.

That will happen with a two second gap as well. You simply drop back and
leave the same gap behind that one. It doesn't make any significant
difference to the journey time.

Agreed but it can add to the frustration as more and more drivers get
in front of you.

As I said, it makes no significant difference to the journey time, so
why should it create any frustration?


Because people aren't robots.

Most people see it both as slowing them down (even if only a little),
and more importantly as "I left a safe gap, now I don't have one and
have to slow down again to make one".

It is frustrating to have to do that, no matter how much logic may
tell you the difference is insignificant.


Maybe too it can make all the difference at red
lights where you can be further delayed....

Not many red lights on motorways and, in any case, the maximum
recommended red period for any light is 120 seconds - hardly a major delay.


But again, it feels like one, particularly on a short journey.
--
Alex Heney, Global Villager
Cause of crash: Inadvertent contact with the ground.
To reply by email, my address is alexDOTheneyATgmailDOTcom

On Mon, 13 Feb 2012 23:44:35 -0800 (PST), Doug
wrote:

On Feb 13, 10:34*pm, Alex Heney wrote:
On Sun, 12 Feb 2012 19:40:08 -0500, "Mr. Bean" wrote:
I feel that that at 70mph, the 2 sec rule between cars is an inadequate
time to avoid a pile up.I would say more like 4 secs.

In that case, your reactions are not adequate to driving in the modern
world, and you should give up your licence.

2 seconds is plenty for any reasonable driver who is paying attention.

And whether you are doing 35 or 75 makes no difference to that, since
the gap is to take account of reaction time before you are slowing at
the same rate as the vehicle in front.

Obviously reaction time is related to speed and stopping distance.

Obviously, but then so is the distance between cars at two seconds
related to speed.


What if the guy in front suddenly stops or crashes?

You should have seen what was in front of him that was going to cause
the crash.

I doubt if 2
seconds will avoid your crash into him at 70+ mph and especially when
you are tinkering with your many car gadgets or glancing at your
passenger or sneezing, etc.. Hence why there are so many pile-ups on
motorways.


Indeed. Most pile ups are cause by lack of observation by drivers of
the 2nd and subsequent vehicles.
--
Alex Heney, Global Villager
I drink to make other people interesting.
To reply by email, my address is alexDOTheneyATgmailDOTcom

Alex Heney wrote:

[....]
Alex Heney, Global Villager
3 kinds of people: those who can count & those who can't.

However it does happen in real life. I have just today come across an official
economists report which mentions a "Twin track approach: Resources, demands and
losses". LOL!

I suppose the problem comes from a desire to use a catchy phrase. A "Triple track
approach" wouldn't quite resonate well with the reader.

On Mon, 13 Feb 2012 23:44:35 -0800 (PST)
Doug wrote:

What if the guy in front suddenly stops or crashes?

About the only thing that will make a car suddenly stop on a
motorway (as in stop faster than the brakes will stop a car) would be a
hole suddenly appearing in the road under the car. I would agree that under
these conditions a two second gap may not be enough to find a way to avoid
a crash.

How often does that happen ?

--
Steve O'Hara-Smith | Directable Mirror Arrays
C:WIN | A better way to focus the sun
The computer obeys and wins. | licences available see
You lose and Bill collects. | http://www.sohara.org/

On 14/02/2012 21:46, Alex Heney wrote:
On Tue, 14 Feb 2012 09:07:22 +0000, Nightjar
wrote:

On 14/02/2012 07:36, Doug wrote:
On Feb 13, 9:30 am,
wrote:
....
That will happen with a two second gap as well. You simply drop back and
leave the same gap behind that one. It doesn't make any significant
difference to the journey time.

Agreed but it can add to the frustration as more and more drivers get
in front of you.

As I said, it makes no significant difference to the journey time, so
why should it create any frustration?


Because people aren't robots.

Most people see it both as slowing them down (even if only a little),
and more importantly as "I left a safe gap, now I don't have one and
have to slow down again to make one".

It is frustrating to have to do that, no matter how much logic may
tell you the difference is insignificant.

I don't find it so.

Maybe too it can make all the difference at red
lights where you can be further delayed....

Not many red lights on motorways and, in any case, the maximum
recommended red period for any light is 120 seconds - hardly a major delay.


But again, it feels like one, particularly on a short journey.

As I was taught when first learning to drive, better late in this world
than early in the next.

Colin Bignell

On Mon, 13 Feb 2012 01:22:58 -0000, Janitor of Lunacy wrote:


"Mr. Bean" wrote in message
...
I feel that that at 70mph, the 2 sec rule between cars is an inadequate
time to avoid a pile up.I would say more like 4 secs.


The problem with a rule of thumb is that is depends on the size of the
thumb, and its location. Driving conditions vary, and failure to adapt
driving behaviour accordingly is prima facie negligent.

Indeed. Anything from 0.5 seconds to 5 seconds I find safe.

--
http://petersparrots.com
http://petersphotos.com

When you're having a really bad day and it seems like people are trying to **** you off, remember it takes 42 muscles to frown and only 4 to extend your middle finger.

On Mon, 13 Feb 2012 10:52:39 -0000, R C Nesbit wrote:

Mr. Bean spoke:
I feel that that at 70mph, the 2 sec rule between cars is an inadequate
time to avoid a pile up.I would say more like 4 secs.

It'll never catch on - it would cost to much to replace the 'keep apart 2
chevrons" with "keep apart 4 chevrons" signs.

And double the width of the motorways to account for the decrease in capacity.

--
http://petersparrots.com
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System error 4C: kernel panic