Traffic lights, fast roads and the point of no return!
Discussion
PhilAsia said:
Thinking distance is still the same. Average reaction time is 0.7secs and 0.3/0.4 for left foot braking.
Left foot braking is a technique used to balance a cars weight transfer using the throttle and the brake at the same time....why on earth would you be doing that approaching traffic lights?If you just mean braking with your left foot, unless you are doing this all day every day and are very experienced then using your right foot will give better performance, modulating the brake with your left foot is not a skill most people have.
My view on the OP is that I wouldn't carry on through that road sequence at 70mph, its too risky
Edited by What The Deuces on Thursday 5th January 10:05
Looking at google maps it is indeed an NSL road but on approach to the junction heee are two signs showing traffic lights ahead and one showing Traffic Light Camera and another as you get closer.
Personally I would slow down a bit, but does seem odd it doesn’t reduce in speed, also when joining it from the road on the left, I couldn’t see any NSL signs for the dual cartiageway. Odd.
Personally I would slow down a bit, but does seem odd it doesn’t reduce in speed, also when joining it from the road on the left, I couldn’t see any NSL signs for the dual cartiageway. Odd.
Edited by Vipers on Thursday 5th January 12:28
Personally if it's recognised that a TL controlled junction has a safety problem with then simply putting a camera with no other measures in place then there is a serious failure in thought process.
Way so many people operate a couple of signs aren't in my very honest opinion not sufficient. The problem may not be you, but the one behind, car in gear, brain in neutral, or the one about to emerge with no thoughts of conflict with other traffic, or that green also means "if safe to do so."
Way so many people operate a couple of signs aren't in my very honest opinion not sufficient. The problem may not be you, but the one behind, car in gear, brain in neutral, or the one about to emerge with no thoughts of conflict with other traffic, or that green also means "if safe to do so."
Pica-Pica said:
My other technique, especially on the fast, large, traffic-light roundabouts between A/M roads, is, if the green is on for some time as I approach, observe behind, check for red-light runners going across, lift off as you approach the last 25 metres or so, and cover the brake, but do not touch the pedal.
Since, in the case of the TL controlled junction on a 70 mph limited road, the go/no-go decision point is about 100 m before the lights, surely the time to start covering the brake is a lot earlier than 25 m. In the case of the red light runner, if you leave it till 25 m to start to brake you will probably hit them at about 60.More seriously, we are all agreed that approaching a TL controlled junction on a fast road we should be ready to stop and perhaps reducing speed below the limit.
My doubts arise about how firmly we should expect to brake if lights change to amber on approach. The HWC says stop if safe to do so. I think most of us interpret that as meaning 'stop if safe and comfortable to do so'. Most drivers don't. We do not expect to carry out an emergency stop - and at the 30 or 40 limit speeds applying around the vast majority of TL controlled junctions, the 3 second amber period gives you ample time to go through if you cannot stop comfortably.
What The Deuces said:
Left foot braking is a technique used to balance a cars weight transfer using the throttle and the brake at the same time....why on earth would you be doing that approaching traffic lights?
If you just mean braking with your left foot, unless you are doing this all day every day and are very experienced then using your right foot will give better performance, modulating the brake with your left foot is not a skill most people have.
There could be a whole different discussion about left foot braking. In a world where cars with a clutch pedal are a dying breed, and in emergency braking with the left foot can save 0.5 seconds thinking time, shouldn't left foot braking become the norm?If you just mean braking with your left foot, unless you are doing this all day every day and are very experienced then using your right foot will give better performance, modulating the brake with your left foot is not a skill most people have.
Incidentally, the late great Pentti Airikkala (Finnish rally driver) ran a left foot braking course. He proposed several benefits of LFB, though not the one mentioned above. One was saving thinking time, and he argued that even in a manual car it is a good idea to cover the brake pedal with the left foot on the grounds that in emergency it is better to stop in time and stall the engine than to keep the engine running and have an accident.
I routinely left foot brake in auto cars, but not in manual cars. I agree that developing the skill of accurate and smooth braking with your left foot if you have not been used to doing it requires considerable practise.
waremark said:
There could be a whole different discussion about left foot braking. In a world where cars with a clutch pedal are a dying breed, and in emergency braking with the left foot can save 0.5 seconds thinking time, shouldn't left foot braking become the norm?
Incidentally, the late great Pentti Airikkala (Finnish rally driver) ran a left foot braking course. He proposed several benefits of LFB, though not the one mentioned above. One was saving thinking time, and he argued that even in a manual car it is a good idea to cover the brake pedal with the left foot on the grounds that in emergency it is better to stop in time and stall the engine than to keep the engine running and have an accident.
I routinely left foot brake in auto cars, but not in manual cars. I agree that developing the skill of accurate and smooth braking with your left foot if you have not been used to doing it requires considerable practise.
And therein lies the issue IMO. Ive been lfb for 20 years on the roads and its still not second nature in an emergencyIncidentally, the late great Pentti Airikkala (Finnish rally driver) ran a left foot braking course. He proposed several benefits of LFB, though not the one mentioned above. One was saving thinking time, and he argued that even in a manual car it is a good idea to cover the brake pedal with the left foot on the grounds that in emergency it is better to stop in time and stall the engine than to keep the engine running and have an accident.
I routinely left foot brake in auto cars, but not in manual cars. I agree that developing the skill of accurate and smooth braking with your left foot if you have not been used to doing it requires considerable practise.
mac96 said:
In recent years some junctions like that seem to have grown a short stretch of 40mph or 50mph limit, to encourage people to slow down on approach to the lights even when on green.
Seems like a good idea even if no reduced limit. Of course I mean gentle slowing down, not standing on the brake.
One of the very few times I've been caught speeding. It was back in 2002. Seems like a good idea even if no reduced limit. Of course I mean gentle slowing down, not standing on the brake.
A junction where it was 60mph both sides but for a brief time while crossing the junction they had phased speed reduction just for crossing the junction with a ton of other distractions I didn't see the mobile speed camera.
So meant for safety but also creates an opportunity at the same time!
ingenieur said:
One of the very few times I've been caught speeding. It was back in 2002.
A junction where it was 60mph both sides but for a brief time while crossing the junction they had phased speed reduction just for crossing the junction with a ton of other distractions I didn't see the mobile speed camera.
So meant for safety but also creates an opportunity at the same time!
I recall a case some time ago, a woman got for something, she had a degree in something to with eye recognition etc, and she sucessfully presented a case to the judge at the particular juncion she was done for had so many road signs it was just about impossible to see and inwardly digest what they all meant, case was dismissed.A junction where it was 60mph both sides but for a brief time while crossing the junction they had phased speed reduction just for crossing the junction with a ton of other distractions I didn't see the mobile speed camera.
So meant for safety but also creates an opportunity at the same time!
Vipers said:
ingenieur said:
One of the very few times I've been caught speeding. It was back in 2002.
A junction where it was 60mph both sides but for a brief time while crossing the junction they had phased speed reduction just for crossing the junction with a ton of other distractions I didn't see the mobile speed camera.
So meant for safety but also creates an opportunity at the same time!
I recall a case some time ago, a woman got for something, she had a degree in something to with eye recognition etc, and she sucessfully presented a case to the judge at the particular juncion she was done for had so many road signs it was just about impossible to see and inwardly digest what they all meant, case was dismissed.A junction where it was 60mph both sides but for a brief time while crossing the junction they had phased speed reduction just for crossing the junction with a ton of other distractions I didn't see the mobile speed camera.
So meant for safety but also creates an opportunity at the same time!
What The Deuces said:
waremark said:
…I routinely left foot brake in auto cars, but not in manual cars. I agree that developing the skill of accurate and smooth braking with your left foot if you have not been used to doing it requires considerable practise.
And therein lies the issue IMO. Ive been lfb for 20 years on the roads and its still not second nature in an emergencyAs a side point, people should practise emergency stops, especially in modern cars when the car detects and applies an emergency brake action, and the hazards come on until you drive away or switch them off. That threw me first time.
whimsical ninja said:
modellista said:
At 70mph you have no margin for error - closer than 95m (3 seconds) you have to go, further than that, you have to brake.
At 80mph and 120m (3 seconds again), you're stuck - too far away to get through (you need 107m), but too close to stop (you need 133m). Too fast for the junction.
Cracking bit of work there and fascinating result.At 80mph and 120m (3 seconds again), you're stuck - too far away to get through (you need 107m), but too close to stop (you need 133m). Too fast for the junction.
Reality is that 70mph is probably too fast to be steaming through a lot of junctions from a safety point of view...but your analysis above does tend towards a "damned if you do, damned if you don't" result when doing a legal speed. At least, the margin for error is so small that the chances of doing something either dangerous or illegal are fairly high.
Even using the junction in the OP regularly and knowing what it's like, I still found myself in that 50/50 position a few weeks ago and elected to continue - the lights were red as I crossed the line and nothing has happened.
Pica-Pica said:
What The Deuces said:
waremark said:
…I routinely left foot brake in auto cars, but not in manual cars. I agree that developing the skill of accurate and smooth braking with your left foot if you have not been used to doing it requires considerable practise.
And therein lies the issue IMO. Ive been lfb for 20 years on the roads and its still not second nature in an emergencyAs a side point, people should practise emergency stops, especially in modern cars when the car detects and applies an emergency brake action, and the hazards come on until you drive away or switch them off. That threw me first time.
Last year, maybe, dark night on a not very well lit road about to pass junction to the left for access road to a supermarket, even worse lighting. One vehicle well behind.
Peripheral vision caught some lights bombing up the road to my left, turned out to be group of teenage neds on those stupid scooters with which they try and have a collision. Spidery senses on full alert as they were approaching fast but not close enough to the actual junction, however completely ready for something.
Just as about to pass the junction the lead ned, who at that point had not been seen, well ahead of the others, no lights, black scooter, black helmet, face mask, jacket, yep everything black no reflectors, shot out right in front of me. Jesus titting Christmas, how we missed still don't know. In that case both feet were firmly side by side on the brake pedal.
What The Deuces said:
And therein lies the issue IMO. Ive been lfb for 20 years on the roads and its still not second nature in an emergency
I still remember the first time I had to brake in a not quite emergency but suddenly and unexpectedly and used my left foot - I immediately thought 'now I've cracked it'. Less than 20 years of practise, but quite a bit.The speed limit is not a target.
Just because the speed limit is 70, it does not mean it's safe or sensible to cross the junction at that speed.
Even in a driving test, you are expected to anticipate what will happen next; and that's not hard when looking at a green light...
Slow down!
Just because the speed limit is 70, it does not mean it's safe or sensible to cross the junction at that speed.
Even in a driving test, you are expected to anticipate what will happen next; and that's not hard when looking at a green light...
Slow down!
Edited by OverSteery on Thursday 5th January 19:11
waremark said:
What The Deuces said:
And therein lies the issue IMO. Ive been lfb for 20 years on the roads and its still not second nature in an emergency
I still remember the first time I had to brake in a not quite emergency but suddenly and unexpectedly and used my left foot - I immediately thought 'now I've cracked it'. Less than 20 years of practise, but quite a bit.I don’t think it’s something we should encourage the masses to learn ‘live’ on the road
Sheepshanks said:
I know this is an oldish thread, but I don't think anyone has mentioned that you've also got 1.2 seconds after red appears so the timings are not as tight as suggested.
What is that 1.2 seconds, is it the time from red on your lights to green on the crossing lights or is it a grace period before a penalty from traffic light cameras? Do you have a reference for it?Part of the difficulty with this sort of situation is how well prepared you are for an emergency stop.
If I'm by myself in a good car, with good brakes and there's nobody right behind me then stopping as quickly as possible at the last minute to avoid setting off the camera is fine and I can drive as if that possibility could come up.
The opposite of that scenario is being loaded with either people or unwieldy cargo and not wishing to be forced into an emergency braking scenario by either another driver or poor timing approaching a revenue generator. Or perhaps if in a less than ideal vehicle. Up until recently I owned a 1992 London taxi which had good but old fashioned brakes. You really don't want to be doing an emergency stop in that thing. And if you have anybody riding in the back more often than not it customary not to use the seat belts!
If I'm by myself in a good car, with good brakes and there's nobody right behind me then stopping as quickly as possible at the last minute to avoid setting off the camera is fine and I can drive as if that possibility could come up.
The opposite of that scenario is being loaded with either people or unwieldy cargo and not wishing to be forced into an emergency braking scenario by either another driver or poor timing approaching a revenue generator. Or perhaps if in a less than ideal vehicle. Up until recently I owned a 1992 London taxi which had good but old fashioned brakes. You really don't want to be doing an emergency stop in that thing. And if you have anybody riding in the back more often than not it customary not to use the seat belts!
I go through this almost daily.
It's 50 mph on approach to the limit change. I stick to roughly 50 mph until I'm through this junction, then accelerate.
Usually if you come around the corner just after Grestys waste, if the lights are already green, I expect them to change. There's no real timing on them as such as the junction from Kelsall is sensored.
It's 50 mph on approach to the limit change. I stick to roughly 50 mph until I'm through this junction, then accelerate.
Usually if you come around the corner just after Grestys waste, if the lights are already green, I expect them to change. There's no real timing on them as such as the junction from Kelsall is sensored.
When approaching traffic lights on fast roads, it is important to maintain a safe following distance from the vehicle in front of you. This will allow you to stop safely if the traffic lights change unexpectedly.
One way to gauge your stopping distance is to use landmarks such as lamp posts, as you mentioned. Another method is to use the "two-second rule," which states that you should aim to be at least two seconds behind the vehicle in front of you. This can be determined by picking a stationary object ahead, such as a sign or tree, and counting the seconds it takes for you to reach that object after the vehicle in front of you has passed it.
It's important to be aware of the traffic lights cameras and avoid getting caught out by breaking the rules and causing a danger.
It's also important to look out for any advanced traffic signals that are placed before the traffic lights, as these will give you an indication of the status of the lights ahead of you, and it could help you to adjust your speed accordingly.
Lastly, always obey traffic signals and be prepared to stop if the lights change unexpectedly, as this will prevent accidents and help keep you and other road users safe.
One way to gauge your stopping distance is to use landmarks such as lamp posts, as you mentioned. Another method is to use the "two-second rule," which states that you should aim to be at least two seconds behind the vehicle in front of you. This can be determined by picking a stationary object ahead, such as a sign or tree, and counting the seconds it takes for you to reach that object after the vehicle in front of you has passed it.
It's important to be aware of the traffic lights cameras and avoid getting caught out by breaking the rules and causing a danger.
It's also important to look out for any advanced traffic signals that are placed before the traffic lights, as these will give you an indication of the status of the lights ahead of you, and it could help you to adjust your speed accordingly.
Lastly, always obey traffic signals and be prepared to stop if the lights change unexpectedly, as this will prevent accidents and help keep you and other road users safe.
waremark said:
What is that 1.2 seconds, is it the time from red on your lights to green on the crossing lights or is it a grace period before a penalty from traffic light cameras? Do you have a reference for it?
Several years ago I had to take a naughty boy red-light course. (If anyone cares, I got "done" for driving through a red light at zero mph in traffic and decided it was easier to take the course than try and argue that due to heavy traffic the car crossed the white line when the lights were green but was held in the junction by traffic for long enough for the lights to turn red.)
On the course, the chappy presenting shot someone down - who said they didn't have time to stop before the lights turned red. He triumphantly proclaimed that you had 3 seconds of amber, and a further second of red before the camera was triggered, therefore if you got caught you'd had at least 4 seconds to stop, which was plenty of time. I think the guy being berated had said he was caught by a camera at a junction in a 30 zone. I logged the "3+1 seconds" away as something that potentially might be useful to know.
I have no idea if this was just him saying things to appear like he knew what he was talking about ... but it's further corroboration of the "1 second grace period" mentioned above.
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