Is engine braking good or bad?

Is engine braking good or bad?

Author
Discussion

7mike

3,012 posts

194 months

Monday 31st December 2012
quotequote all
DukeDickson said:
His problem, not yours. No more complicated than that.
jamieduff1981 said:
I don't think I'm an advanced motorist. I've never joined the IAM or taken extra training or anything like that.

Everyone loses in a crash -
A good example of why positive beliefs & attitude are worth far more than a certificate.

real4star

Original Poster:

7,032 posts

138 months

Monday 31st December 2012
quotequote all
jaspermolly said:
Is it possible that if proven the op could be open to,Driving without reasonable consideration for other road users.

Jaspermolly.
One of the reasons I posted.

Like I said... I don't like the idea that people rely on the car directly in front braking to tell them to slow down. But if that's the way it is I shall adjust my driving style to suit.

I do think about other drivers and what they may/could/should do, but I can't be expected to (shouldn't have to) think FOR them as well surly?


Edited by real4star on Monday 31st December 19:22

SystemParanoia

14,343 posts

199 months

Monday 31st December 2012
quotequote all
no.

you can only drive your own car, for you.

BertBert

19,084 posts

212 months

Monday 31st December 2012
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I think we need to get real about brake lights. They are a primary signal that the car in front is slowing. Yes you can tell from the change in distance, but we actually rely on the brake lights of the car in front.

The "2 second rule" is predicated on the car in front showing its brake lights.

Bert

scottdd

39 posts

137 months

Tuesday 1st January 2013
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It is scary and eye opening that so many people rely on brake lights to decide whether or not the car in front is slowing.

Probably explains why so many people are rear ended when they are stopped with their handbrake on at junctions because people need bright red lights to tell them to slow down.

jamieduff1981

8,028 posts

141 months

Tuesday 1st January 2013
quotequote all
I think that's rubbish. If light signals were not considered to be important then vehicles would not be required to have them and driving around with defective lights wouldn't be an offence.

It's far from the only thing people rely on, but it is an excellent early warning system.

Everyone should be aware that human depth perception is extremely unreliable and cannot be trusted. It works by measuring very small angular changes between your eyeballs as they converge on a nearer target. Huge differences in distance are needed for tiny changes in what your brain perceives to be distance. When not relying on depth perception itself, you rely on the image itself changing (i.e. relative movement). That again consumes precious time as you watch for a picture to evolve.

Brake lights (should, if the brakes are used) offer a clear and instant indicator that the car in front is slowing giving everyone else much more time to react in a safe manner. By not using your brake lights you are absolutely assured (even with your superhuman advanced driver techniques) to consume more time and allow a greater speed differential to develop with less space between you before you even acknowledge that the situation is changing.

Frankly, anyone who does not appreciate the advance warning that brake lights provide are the ones that worry me on the road, because they clearly place far, far too much trust in a human system which is scientifically accepted to be very approximate and slow to update at best.

SystemParanoia

14,343 posts

199 months

Tuesday 1st January 2013
quotequote all
BertBert said:
The "2 second rule" is predicated on the car in front showing its brake lights. doing something retarded!

Bert

Hooli

32,278 posts

201 months

Tuesday 1st January 2013
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jamieduff1981 said:
Frankly, anyone who does not appreciate the advance warning that brake lights provide are the ones that worry me on the road, because they clearly place far, far too much trust in a human system which is scientifically accepted to be very approximate and slow to update at best.
Do you know, it can take me miles to realise that the car in front has non-functional brake lights because they only serve to confirm what you can see rather than being a primary indication.

rsv gone!

11,288 posts

242 months

Tuesday 1st January 2013
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But if that car does anything unexpected like stand on the anchors it will catch you out.

jamieduff1981

8,028 posts

141 months

Tuesday 1st January 2013
quotequote all
Hooli said:
Do you know, it can take me miles to realise that the car in front has non-functional brake lights because they only serve to confirm what you can see rather than being a primary indication.
Yes I've noticed that too. Infact, I usually need to wait for the car in front to come to a halt before I can safely conclude that they are braking but there are no brake lights, unless of course they perform an extremely rapid deceleration.

I would still much rather the red lights came on though so that I get instant notification rather than waiting until I realise we're closing, and I'd still rather make sure my red lights come on incase the person behind is a bit too slow in realising what's going on. I just don't want my pride and joy shunted!

jaspermolly

19 posts

137 months

Tuesday 1st January 2013
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The "2 second rule" is predicated on the car in front showing its brake lights.

Bert

I think I have a different understanding of the 2 second rule please could you explain how it would be used in this situation.

Thanks jaspermolly

SystemParanoia

14,343 posts

199 months

Tuesday 1st January 2013
quotequote all
2 second rule advert biggrin

http://youtu.be/mf5d2DP4Pp0

jaspermolly

19 posts

137 months

Tuesday 1st January 2013
quotequote all
My understanding exactly and increase to 4 seconds if it wet,but I cannot link this to Berts reply about brake lights!

Note on the video it only helps at higher speeds as I have said in a post further up its only useful above 40MPH.

Japermolly

ScoobyChris

1,703 posts

203 months

Tuesday 1st January 2013
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jaspermolly said:
My understanding exactly and increase to 4 seconds if it wet,but I cannot link this to Berts reply about brake lights!
When driving, you aim to drive at a speed such that you can stop in the distance you can see to be clear. The 2 second rule is a slight compromise on this in that it relies on the car in front not coming to a dead stop. My understanding of what Bert is saying is that the basis of leaving a 2 second distance is that it gives you enough time to react at the point where you know the car in front is slowing down (ie when the brake lights come on) rather than waiting for your brain to clock the vehicle's change in speed which could take considerably longer as well as eating into the distance you travel before reacting.

Of course I may have completely misinterpreted what he said winkbiggrin

Chris

7mike

3,012 posts

194 months

Tuesday 1st January 2013
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The official DSA guide to Driving says (regarding the 2-second rule): "In heavy, slow-moving urban traffic that might not be practicle, without wasting valuable road space. However, even then, the gap should never be less than your thinking distance, and much more if the road is wet and slippery."

Not sure about the OPs local Tesco but most tend to be around busy urban roads in my experience.

BertBert

19,084 posts

212 months

Tuesday 1st January 2013
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ScoobyChris said:
Of course I may have completely misinterpreted what he said winkbiggrin
Not far off. The so called "2 second rule" gives you enough reaction time to be able to react to the car in front slowing. As the poster above describes, "change of depth" perception alone is not very good and if brake lights hadn't been invented, the rule would probably be the 4, 6, or 8 second rule.

I'm interested in what people are saying about their experiences with no brake lights. The number of times this happens is very low as cars with no brake lights at all are pretty rare. Of course there are lots of other visual clues to tell you what's going on which is why I described brake lights as a primary information source, not the only one.

However I suspect that even the driving deities of PH would come to grief without brake lights. If you are following a car using a "2 second" gap and you don't yet know their brake lights are out and they do a snappy stop with no warning most will struggle to stop in time.

Hey ho, as I say, hard to show as the circumstances don't arise too often.

Bert
PS the last car I rear-ended had failed brake lights! biggrin

7db

6,058 posts

231 months

Tuesday 1st January 2013
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7mike said:
The official DSA guide "...without wasting valuable road space"
I think that's misguided. Roadspace isn't valuable, it's vehicle throughput that is. If more space and more speed means higher throughput then that's better than a more densely packed road.

Optimising the wrong thing might also explain why people drive badly in dense traffic.

7mike

3,012 posts

194 months

Tuesday 1st January 2013
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7db said:
I think that's misguided. Roadspace isn't valuable, it's vehicle throughput that is. If more space and more speed means higher throughput then that's better than a more densely packed road.

Optimising the wrong thing might also explain why people drive badly in dense traffic.
I also think a lot of driver's "thinking distance" may be a little optomistic. However as all manner of circumstances are constantly changing I doubt trying to assess a two second gap is going to be of much use at slower speeds on urban roads.

Frix

678 posts

192 months

Wednesday 2nd January 2013
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I also have a 1960 Land Rover and the majority of complaints are that it doesn't go fast enough. I assume that is what the non-highway code hand gestures are anyway biggrin

7mike

3,012 posts

194 months

Wednesday 2nd January 2013
quotequote all
Frix said:
I also have a 1960 Land Rover and the majority of complaints are that it doesn't go fast enough. I assume that is what the non-highway code hand gestures are anyway biggrin
No mate, they're just wafting away the fumes hehe