OT: red light jumping

[Just zis Guy, you know?]

On Tue, 14 Dec 2004 14:47:44 +0000, Tony Raven <[email protected]>
wrote in message <[email protected]>:

>The slowing down will help but covering the brake only saves about 200ms.

The reason for covering the brake is to ensure that the default action
becomes braking rather than accelerating, should something unexpected
happen. My driving instructor was quite keen on that one.

My driving instructor was John Milne, now MBE and Head of Training at
the Approved Driving Instructors National Joint Council, an old friend
of the family whose late wife used to give me second helpings of pud
in the college canteen. Back then he was not an MBE, although the
Pater informs me he was one of five people employed by the DoT as was
to assess driving instructor examiners. Another was Fred Williams,
who taught my sister. Dad was active in road safety in St Albans in
nineteen hundred and frozen to death, so he picked us the best
instructors he could find. And then took me out to practice in a car
which, as it turned out, had no brakes, which meant some fast
learning...

Guy
--
"then came ye chavves, theyre cartes girded wyth candels
blue, and theyre beastes wyth straynge horn-lyke thyngs
onn theyre arses that theyre fartes be herde from myles
around." Chaucer, the Sheppey Tales

 

[Tim Woodall]

On Tue, 14 Dec 2004 07:44:43 +0000,
Tony Raven <[email protected]> wrote:
> Tim Woodall wrote:
>>
>> I think the amber phase of most lights is of the order of 3 seconds.
>>
>> Allow a respectable 0.5g braking and you get a speed a little over
>> 30mph that you can stop from.
>>
>
> You've forgotten to allow for reaction times before you start braking.
> You need at least 1.25s for that.
> http://www.visualexpert.com/Resources/reactiontime.html
>
You snipped:
>> (I'm ignoring thinking times here)

So no i didn't forget them.

And in this instance 1.25 seconds is long. I'm assuming you are
approaching the green lights and have seen them and are anticipating
that they might change.

I would expect perception time to approach zero - you are waiting for
the light to change. The physical motion of the leg is still going to
take around 0.2 seconds.

Olympic sprinters have _left_ the blocks within 0.5 seconds of the
gun going off.

http://condellpark.com/kd/reactiontime.htm

For about 120 years, the accepted figures for mean simple reaction times
for college-age individuals have been about 190 ms (0.19 sec) for light
stimuli and about 160 ms for sound stimuli (Galton, 1899; Fieandt et
al., 1956; Welford, 1980; Brebner and Welford, 1980).

Elite 100 m sprinters are way above the mean in at least running
performance, but their mean reaction times are not much better than the
average. For example, in the July 12 2003 Rome Golden League A & B
Series 100m sprints, reaction times averaged 153 mS (standard deviation
28 mS) - the minimum was 110 mS, max was 242 mS; there was virtually no
correlation between running time and reaction time (r^2=0.02).


Tim.


--
God said, "div D = rho, div B = 0, curl E = - @B/@t, curl H = J + @D/@t,"
and there was light.

http://tjw.hn.org/ http://www.locofungus.btinternet.co.uk/

 

[Tony Raven]

Tim Woodall wrote:

>>http://www.visualexpert.com/Resources/reactiontime.html

>
> And in this instance 1.25 seconds is long. I'm assuming you are
> approaching the green lights and have seen them and are anticipating
> that they might change.
>
> I would expect perception time to approach zero - you are waiting for
> the light to change. The physical motion of the leg is still going to
> take around 0.2 seconds.
>

Try reading the link I posted. 1.25s is the typical reaction time to
traffic lights. Its not just reacting. There is also the time to notice
the change and then the thinking time to assess whether you should carry
on and cross on amber or brake and stop. So add another 3s to slow at
0.5g from 30mph. That makes it crossing the line 1.25s after the lights
have gone red if they change when you are at the worst place.

Tony

 

[Jack Ouzzi]

On Wed, 15 Dec 2004 00:17:28 +0000, Tony Raven <[email protected]>
wrote:

>Tim Woodall wrote:
>
>>>http://www.visualexpert.com/Resources/reactiontime.html
>
>>
>> And in this instance 1.25 seconds is long. I'm assuming you are
>> approaching the green lights and have seen them and are anticipating
>> that they might change.
>>
>> I would expect perception time to approach zero - you are waiting for
>> the light to change. The physical motion of the leg is still going to
>> take around 0.2 seconds.
>>
>
>Try reading the link I posted. 1.25s is the typical reaction time to
>traffic lights. Its not just reacting. There is also the time to notice
>the change and then the thinking time to assess whether you should carry
>on and cross on amber or brake and stop. So add another 3s to slow at
>0.5g from 30mph. That makes it crossing the line 1.25s after the lights
>have gone red if they change when you are at the worst place.
>
>Tony

 

[Jack Ouzzi]

On Wed, 15 Dec 2004 08:44:20 +0000, Jack Ouzzi
<[email protected]> wrote:

>On Wed, 15 Dec 2004 00:17:28 +0000, Tony Raven <[email protected]>
>wrote:
>
>>Tim Woodall wrote:
>>
>>>>http://www.visualexpert.com/Resources/reactiontime.html
>>
>>>
>>> And in this instance 1.25 seconds is long. I'm assuming you are
>>> approaching the green lights and have seen them and are anticipating
>>> that they might change.
>>>
>>> I would expect perception time to approach zero - you are waiting for
>>> the light to change. The physical motion of the leg is still going to
>>> take around 0.2 seconds.
>>>
>>
>>Try reading the link I posted. 1.25s is the typical reaction time to
>>traffic lights. Its not just reacting. There is also the time to notice
>>the change and then the thinking time to assess whether you should carry
>>on and cross on amber or brake and stop. So add another 3s to slow at
>>0.5g from 30mph. That makes it crossing the line 1.25s after the lights
>>have gone red if they change when you are at the worst place.
>>
>>Tony

Whoops, sorry got a new mouse and the buttons are a bit more
sensitive

 

[Trevor Barton]

On Tue, 14 Dec 2004 19:27:58 +0000, Just zis Guy, you know? wrote:
> My driving instructor was John Milne, now MBE and Head of Training at
> the Approved Driving Instructors National Joint Council, an old friend
> of the family whose late wife used to give me second helpings of pud
> in the college canteen. Back then he was not an MBE, although the
> Pater informs me he was one of five people employed by the DoT as was
> to assess driving instructor examiners. Another was Fred Williams,
> who taught my sister.

> Dad was active in road safety in St Albans in
> nineteen hundred and frozen to death,

Eh?

> so he picked us the best
> instructors he could find. And then took me out to practice in a car
> which, as it turned out, had no brakes, which meant some fast
> learning...
>
> Guy
> --
> "then came ye chavves, theyre cartes girded wyth candels
> blue, and theyre beastes wyth straynge horn-lyke thyngs
> onn theyre arses that theyre fartes be herde from myles
> around." Chaucer, the Sheppey Tales


--
Trevor Barton

 

[David Martin]

On 15/12/04 9:00 am, in article [email protected],
"Trevor Barton" <[email protected]> wrote:

>
>> Dad was active in road safety in St Albans in
>> nineteen hundred and frozen to death,
>
> Eh?

A long time ago.

...d

 

[Peter B]

"Just zis Guy, you know?" <[email protected]> wrote in message
news:[email protected]...
> Incidentally, it is good practice to slow down and cover the brake
> when approaching light-controlled junctions. Or so my driving
> instructor told me.

Wrong!
Best practice is to cover the accelerator so that if the lights turn to
amber one can react immediately. Or so Arriva driving instructors seem to
tell their trainees.

Pete

 

[Peter B]

"JLB" <[email protected]> wrote in message
news:[email protected]...
> Hence it was pretty much off topic, because
> it was about vehicle traffic and had little to say about cyclists or
> cycling.

Actually I think it is relevent to cyclists as traffic.
Not least because I know of junctions where I go over the line on green but
before clearing the junction the lights are well into their red phase, this
has two potential effects: I could be perceived as another red light jumping
cyclist and could become victim of someone who's too quick off the mark and
hasn't registered my presence.

Pete

 

[Peter B]

"dkahn400" <[email protected]> wrote in message
news:[email protected]...
> The police of course were probably much more attracted by the
> "emergency" stop than they would have been by routine red light
> running.

Which reminds me of many years ago when I pulled off smartly to make a right
turn at Weedon (IIRC) across the path of a slow moving lorry some way off.
An ossifer of the law who heard my wheels spin collared me an issued forth
the statement: "I don't know what you did back there but it sounded
dangerous".
With that kind of reasoning ability no wonder they're being replaced by
cameras.

Pete

 

[Badger]

Colin Blackburn wrote:

> Provence1971 wrote:
>
>> The police officer did nothing of course
>>
> To be fair he was actually dealing with another incident at the time.

Hummm, I wonder if our porsche driving vice chancellor who regularly
cuts people up, fails to indicate, and launches on the amber (why wait
for the green) would get ignored, or nicked and then have the case
dropped????
The buggers even had his reg c5 koo mis-spaced to read C5K 00 with the 5
almost an S....

 

[David Nutter]

Badger <[email protected]> said:
>
>
> Colin Blackburn wrote:
>
>> Provence1971 wrote:
>>
>>> The police officer did nothing of course
>>>
>> To be fair he was actually dealing with another incident at the time.
>
> Hummm, I wonder if our porsche driving vice chancellor who regularly
> cuts people up, fails to indicate, and launches on the amber (why wait
> for the green) would get ignored, or nicked and then have the case
> dropped????

Ah, so that's Wee Kenny (can't be too many insanely driven Porsches in
Durham). Figures. I snigger everytime I remember the Convocation where that
odious little twerp disavowed portions of a document ostensibly written by
him. Nor can I forget his heroic "escape", with the help of some university
security guards, from a party of ne'er do-wells coming to attack him in
his home. Namely the student LARP society who happened to be walking
past, holding deadly weapons like foam swords...

Despite the crazed Porsche-equipped VCs, the overall standard of driving in
Durham is great compared to Lincs Basic Standard Driving[1]. I miss the
hills too. Lincs is too bloody flat and windy.

Regards,

-david, ex Durham

[1] Brakes? What're they for? *VROOOOOOM*

 

[njf>badger]

Badger wrote:
> Hummm, I wonder if our porsche driving vice chancellor who regularly
> cuts people up, fails to indicate, and launches on the amber (why wait
> for the green) would get ignored, or nicked and then have the case
> dropped????
> The buggers even had his reg c5 koo mis-spaced to read C5K 00 with the 5
> almost an S....

Thats interesting, someone replied and I could read it at home, but its
not on the news server here.....

 

[Mike Murphy]

I was taught (many years ago) that if your car's front tyres were over
the studs when the lights change then you are OK to continue through
because your are then too close to stop safely. However, I notice that
these studs seem not to be around much nowadays, perhaps they've bneen
abandoned?
- Mike

 

[Tony W]

"Mike Murphy" <[email protected]> wrote in message
news:[email protected]...
> I was taught (many years ago) that if your car's front tyres were over
> the studs when the lights change then you are OK to continue through
> because your are then too close to stop safely. However, I notice that
> these studs seem not to be around much nowadays, perhaps they've bneen
> abandoned?

That dates you. I was taught the same. However, weren't the studs
effectively replaced by the various forms of detection system that now adorn
most lights.

T

 

[Just zis Guy, you know?]

On Wed, 22 Dec 2004 20:49:12 -0000, "Tony W"
<[email protected]> wrote in message
<[email protected]>:

>> I was taught (many years ago) that if your car's front tyres were over
>> the studs when the lights change then you are OK to continue through
>> because your are then too close to stop safely. However, I notice that
>> these studs seem not to be around much nowadays, perhaps they've bneen
>> abandoned?

>That dates you. I was taught the same. However, weren't the studs
>effectively replaced by the various forms of detection system that now adorn
>most lights.

I believe that the white line is the vital mark on the road, and the
purpose of the amber phase is to give you time to stop if you are not
yet over the line.

I am always amused when people come to a screeching halt in the middle
of the junction because the light ahead turns red. You'd almost think
that people didn't read the Highway Code...

Guy
--
"then came ye chavves, theyre cartes girded wyth candels
blue, and theyre beastes wyth straynge horn-lyke thyngs
onn theyre arses that theyre fartes be herde from myles
around." Chaucer, the Sheppey Tales

 

[Tony Raven]

Just zis Guy, you know? wrote:
>
> I believe that the white line is the vital mark on the road, and the
> purpose of the amber phase is to give you time to stop if you are not
> yet over the line.
>
> I am always amused when people come to a screeching halt in the middle
> of the junction because the light ahead turns red. You'd almost think
> that people didn't read the Highway Code...
>

.....and you haven't read about the dilemma zone and the Government
statements on the length of the amber phase relative to the stopping
distance.

Tony

 

[Just zis Guy, you know?]

On Thu, 23 Dec 2004 11:12:11 +0000, Tony Raven <[email protected]>
wrote in message <[email protected]>:

>> I am always amused when people come to a screeching halt in the middle
>> of the junction because the light ahead turns red. You'd almost think
>> that people didn't read the Highway Code...

>....and you haven't read about the dilemma zone and the Government
>statements on the length of the amber phase relative to the stopping
>distance.

I have indeed. I modify my behaviour by slowing down and covering the
brake as I approach the lights, as stated above. Even so, once you
have crossed the line you are supposed to clear the junction.

Guy
--
"then came ye chavves, theyre cartes girded wyth candels
blue, and theyre beastes wyth straynge horn-lyke thyngs
onn theyre arses that theyre fartes be herde from myles
around." Chaucer, the Sheppey Tales

 

[Tony Raven]

Just zis Guy, you know? wrote:
>
>
> I have indeed. I modify my behaviour by slowing down and covering the
> brake as I approach the lights, as stated above. Even so, once you
> have crossed the line you are supposed to clear the junction.
>

Do you really approach each traffic light pre-choosing a point according
to your speed, traffic, weather etc where you will automatically brake
if you haven't passed it and automatically continue or accelerate if you
have? Covering the brake saves about 200ms only - its the do I/don't I
decision making process that takes the time.

Even if I have crossed the white line there are many cases where it is
safer to stop over the line than proceed through the junction.

Tony

 

[Just zis Guy, you know?]

On Thu, 23 Dec 2004 12:04:35 +0000, Tony Raven <[email protected]>
wrote in message <[email protected]>:

>> I modify my behaviour by slowing down and covering the
>> brake as I approach the lights, as stated above. Even so, once you
>> have crossed the line you are supposed to clear the junction.

>Do you really approach each traffic light pre-choosing a point according
>to your speed, traffic, weather etc where you will automatically brake
>if you haven't passed it and automatically continue or accelerate if you
>have? Covering the brake saves about 200ms only - its the do I/don't I
>decision making process that takes the time.

Automatically? Who knows. I do look ahead, see the lights, take my
foot off the loud pedal and cover the brake.

>Even if I have crossed the white line there are many cases where it is
>safer to stop over the line than proceed through the junction.

Indeed. That was not the circumstance I was describing. I was
talking about the people who come to a screeching halt in the middle
of the junction when the light ahead turns red.

Guy
--
"then came ye chavves, theyre cartes girded wyth candels
blue, and theyre beastes wyth straynge horn-lyke thyngs
onn theyre arses that theyre fartes be herde from myles
around." Chaucer, the Sheppey Tales