Clubjazz - Honda Jazz & HR-V Forums
Honda Jazz Forums => Honda Jazz Mk3 2015 - 2020 => Topic started by: ColinB on June 26, 2017, 09:52:40 AM
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The westbound carriageway at the eastern end of the M3 has an unusual temporary speed limit through the roadworks, it's 55 instead of the 50 that you usually find in such circumstances. It wasn't just one or two rogue signs, they were all like that so clearly that was genuinely the limit. The Jazz did not display that speed limit at all, it just showed "---". Not sure whether that's an issue with the software being unable to read the signs (maybe it's only programmed to look for "likely" numbers and doesn't know what to do with unusual ones ?), or maybe the the display just can't show it.
It was interesting that many drivers didn't seem to believe the 55 signs, and stuck resolutely to 50 !
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I suspect you are correct in that it only recognizes common signs. The only other one that mine sees is the no overtaking sign.
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My H-RV consistently misreads a pair of 30 limit signs and displays 120!
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And they want to go to driverless cars!
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There's one point along the A55 where it picks up the limit from an adjacent road and shows 40 instead of (/). What does the limiter do in that situation? One minute your rolling along at NSL (70mph) the next thing the car thinks you're way above the speed limit.
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Interestingly my speed limit recognition system doesn't have such 'modern' problems.
It's called the 'Mark 1 eyeball'.
Vic.
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There's one point along the A55 where it picks up the limit from an adjacent road and shows 40 instead of (/). What does the limiter do in that situation? One minute your rolling along at NSL (70mph) the next thing the car thinks you're way above the speed limit.
Car behaviour in this situation has been previously reported here:
https://clubjazz.org/forum/index.php?topic=8617.msg44156#msg44156
and in the follow-up comment here:
https://clubjazz.org/forum/index.php?topic=8617.msg44161#msg44161
That's the reason why I don't use the so-called Intelligent Speed Limiter. How would it respond in the situation where a 55 limit isn't being recognised or displayed ? Dunno, didn't try because I didn't want to risk getting points finding out. I prefer to set the "normal" speed limiter manually.
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Yikes! Definitely a bad idea to use the limiter then. I assumed it only stopped acceleration not that it actually slowed you down. I've not bothered to look into it myself because I'm annoyingly(*) good about not exceeding the speed limit. I take pride in it. But it is occasionally nice to be able to glance at the dash to confirm the current limit if bushes or parked vehicles have obscured a repeater sign.
(*)It sometimes seems like I'm annoying every other driver on the road by doing it :-/
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It sometimes seems like I'm annoying every other driver on the road by doing it
Snap. I sometimes feel threatened by other motorists by sticking to the posted limit. Especially in 20 mph zones. The thing is, I go my my GPS speedometer, which reads 10% higher than the car's speedo. Imagine if I was sticking to that!
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It sometimes seems like I'm annoying every other driver on the road by doing it
Snap. I sometimes feel threatened by other motorists by sticking to the posted limit. Especially in 20 mph zones. The thing is, I go my my GPS speedometer, which reads 10% higher than the car's speedo. Imagine if I was sticking to that!
My speedo reads low but not hugely so. It's going to vary according to how the tyres wear but last month it seemed to be reading 50mph when my sat nav reckoned 48 and 70 was actually 65 so it seems like a non-linear relationship. But I just don't care. No one is going to really notice the difference in journey times unless they are going hundreds of miles along a motorway. For a typical daily commute +/- even 20mph on the open road will be swallowed up at junctions at one or both ends.
My commute is straight out to main road then 9 miles at 50mph (with a mile at 30mph in the middle) then four miles, five roundabouts and a lot of traffic. Sometimes there's an HGV or even a tractor that knocks the 50mph section down to 40mph or even 30mph. It never makes any significant different to my arrival time. The only thing that does is severe congestion (like when the M40 barfs and Banbury's primary egress clogs up)..and the recent roadworks at the roundabout outside our office.
But on the open road nothing seems to have much impact..it's all dwarfed by what happens in the Town.
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My satnav says my speedo reads 2mph high when above 40mph otherwise it's accurate.
Even in a county like Lincolnshire there is very little point in rushing about, you will always catch up something going slower than you are and the overtaking opportunities are few and far between.
Maybe that's why the county has one of the highest accident rates in the country. Death rate this year averaging three a month and it's a good year!
Vic.
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I regularly drive through a huge section of Average Speed Cameras, as they build the new Forth Crossing (opening 30th August), and I like to keep as near to the 40 limit as I can. I reckon on 40 + 10%, so try and keep at or just below 44 on the GPS, knowing that average speed drops away very quickly as soon as you fall below by any amount. No real reason. It is just a bit of a challenge. But it only takes a slower car sitting in lane two and it all comes to nought!
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I read somewhere the other day that drivers who break speed limits and drive too fast for conditions on average save about 27 seconds per day. I wouldn't mind betting they then spend more than 27 seconds de-stressing.
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I regularly drive through a huge section of Average Speed Cameras, as they build the new Forth Crossing (opening 30th August), and I like to keep as near to the 40 limit as I can. I reckon on 40 + 10%, so try and keep at or just below 44 on the GPS, knowing that average speed drops away very quickly as soon as you fall below by any amount. No real reason. It is just a bit of a challenge. But it only takes a slower car sitting in lane two and it all comes to nought!
I live near the bridges, my satnav gives an average of 37mph when I go through at cruise control set at 40 mph.
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That's about what I find too.
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I agree that if you stick to speed limit there are quite a few drivers that try to 'push you' into going faster by sitting close to your rear bumper, doesn't work with me.
It is a bit of a worry that car with speed sign recognition can suddenly decide to slow down without at least putting brake lights on.
Here are a some sites with complaints about both Tesla autopilot bad behavior and Audi speed limit recognition problems
https://www.youtube.com/watch?v=mqpsbMCXSyc (https://www.youtube.com/watch?v=mqpsbMCXSyc)
https://forums.tesla.com/forum/forums/anyone-else-having-too-many-autpilot-close-calls (https://forums.tesla.com/forum/forums/anyone-else-having-too-many-autpilot-close-calls)
https://www.audiworld.com/forums/a4-b9-platform-discussion-212/speed-limit-auto-drive-2918391/ (https://www.audiworld.com/forums/a4-b9-platform-discussion-212/speed-limit-auto-drive-2918391/)
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It is a bit of a worry that car with speed sign recognition can suddenly decide to slow down without at least putting brake lights on.
This is not a jab at you culzean, just a general comment.
It's not breaking, it's just slowing due to lack of accelerator use, just like my driving instructor told me to do as I was approaching a reduction in speed limit. In that way you are naturally down to the speed limit as you pass the signs (which is what you are supposed to do by law).
It has been argued elsewhere on the forum that you should avoid using the brakes to save fuel and general wear and tear.
I personally don't see such a driving style as dangerous in any way. The person behind should be two seconds distance, minimum and paying attention to what is going on around them.
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It is a bit of a worry that car with speed sign recognition can suddenly decide to slow down without at least putting brake lights on.
It's not breaking, it's just slowing due to lack of accelerator use, just like my driving instructor told me to do as I was approaching a reduction in speed limit. In that way you are naturally down to the speed limit as you pass the signs (which is what you are supposed to do by law).
Some misunderstanding here. Culzean is correct, that is what happens, and that's why I don't now use the "intelligent" speed limiter.
You are also correct that with appropriate anticipation in normal driving you should be at the speed limit before you reach the sign. But that's not the scenario I described in my earlier post. If you're using the "intelligent" speed limiter in (say) a 40 limit and the computer misreads a 20 sign on an adjoining road, then it thinks you're 20 mph over the speed limit. It responds by sounding a loud alarm and cutting the gas so the car starts to decelerate (it will be slowing down despite the brakes not being used). The rate of deceleration depends on factors such as the road gradient. And yes, the driver behind should have a two second gap and hence have time to respond, although he won't have the benefit of your brake lights to cue him that you're slowing down.
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It is a bit of a worry that car with speed sign recognition can suddenly decide to slow down without at least putting brake lights on.
This is not a jab at you culzean, just a general comment.
It's not breaking, it's just slowing due to lack of accelerator use, just like my driving instructor told me to do as I was approaching a reduction in speed limit. In that way you are naturally down to the speed limit as you pass the signs (which is what you are supposed to do by law).
It has been argued elsewhere on the forum that you should avoid using the brakes to save fuel and general wear and tear.
I personally don't see such a driving style as dangerous in any way. The person behind should be two seconds distance, minimum and paying attention to what is going on around them.
The reason I posted the Audi link is that it shows that the Audi (and probably all systems) suffers from reading ( more likely misreading) speed limit signs that get picked up, normally on adjacent roads, these can be posting a considerably lower limit and cause vehicle to slow down without warning following traffic via brake lights.
Also on the Tesla forum, if the auto drive system loses some of its normal 'cues' e.g. lines on the road, or picks up things that are not normal road lines but it sees them as such the car can do stupid things like swapping lanes or even going to other side road. There are also cases where Tesla system has not 'seen' things like vehicles have stopped ahead and would have ploughed into them at full speed had the driver not braked the car manually. These auto systems are far from sorted.
As for using engine braking to slow a vehicle rather than brakes - this may be good for fuel consumption but I was always told that brake pads are much cheaper than gearboxes, and the gears, bearings and CV joints wear as much from slowing the cars weight down as they do from accelerating it.
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It is a bit of a worry that car with speed sign recognition can suddenly decide to slow down without at least putting brake lights on.
This is not a jab at you culzean, just a general comment.
It's not breaking, it's just slowing due to lack of accelerator use, just like my driving instructor told me to do as I was approaching a reduction in speed limit. In that way you are naturally down to the speed limit as you pass the signs (which is what you are supposed to do by law).
It has been argued elsewhere on the forum that you should avoid using the brakes to save fuel and general wear and tear.
I personally don't see such a driving style as dangerous in any way. The person behind should be two seconds distance, minimum and paying attention to what is going on around them.
The reason I posted the Audi link is that it shows that the Audi (and probably all systems) suffers from reading ( more likely misreading) speed limit signs that get picked up, normally on adjacent roads, these can be posting a considerably lower limit and cause vehicle to slow down without warning following traffic via brake lights.
Also on the Tesla forum, if the auto drive system loses some of its normal 'cues' e.g. lines on the road, or picks up things that are not normal road lines but it sees them as such the car can do stupid things like swapping lanes or even going to other side road. There are also cases where Tesla system has not 'seen' things like vehicles have stopped ahead and would have ploughed into them at full speed had the driver not braked the car manually. These auto systems are far from sorted.
As for using engine braking to slow a vehicle rather than brakes - this may be good for fuel consumption but I was always told that brake pads are much cheaper than gearboxes, and the gears and bearings wear as much from slowing the car as they do from accelerating it.
You were either misinformed or misunderstood. That comment only applies to people generating excessive braking force primarily those who deliberately change down to increase braking effect but possibly also lifting off rapidly at a relatively high rpm in a low gear (eg; 20mph in 2nd and suddenly releasing the accelerator).
Any car that can't handle having the accelerator released at cruising speed in the appropriate gear (eg; 5th at 50mph) is not safe to be driven in the first place. There is absolutely nothing wrong mechanically in using the accelerator to adjust your speed. Where it becomes potentially damaging (and even dangerous) is using the transmission to brake the car. From the sound of it what the Jazz does is not going to harm it in the slightest. It could however catch out a thoughtless tailgater and confuse the driver so has the potential to be dangerous.
More info (https://mechanics.stackexchange.com/questions/1210/does-downshifting-engine-braking-cause-extra-wear-and-tear).
What a lot of drivers don't understand is that those of us skilled at operating the accelerator pedal and anticipation rarely have to do what is commonly referred to as 'braking'. We just constantly adjust our speed in small increments and decrements. The accelerator pedal is all we need to do that ;)
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When intentionally decelerating I often use a very gentle touch of the brake pedal to signal to those behind that I am slowing down (this assumes that the gentle touch is sufficient to put the brake lights on but doesn't actually apply the brakes). I find it entertaining to be travelling in a traffic queue and trying to keep a decent gap between myself and the vehicle in front and just varying the accelerator to adjust the speed while the vehicle in front (usually tailgating) is having to use its brakes.
Getting back on topic, I only use the speed limit recognition as a source of information which is usually, but not always, correct (except when the signs are sparse and it changes to --). I wouldn't want to use it to control the speed.
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If you're using the "intelligent" speed limiter in (say) a 40 limit and the computer misreads a 20 sign on an adjoining road, then it thinks you're 20 mph over the speed limit. It responds by sounding a loud alarm and cutting the gas so the car starts to decelerate (it will be slowing down despite the brakes not being used). The rate of deceleration depends on factors such as the road gradient. And yes, the driver behind should have a two second gap and hence have time to respond, although he won't have the benefit of your brake lights to cue him that you're slowing down.
I absolutely see your point Colin. This is, in my opinion, by far the most annoying aspect of it. I have now learnt how to combat it though: When the alarm sounds, dab the accelerator to the floor until you hear a prolonged beep (this will override the system), then manually control your speed at 40. When you pass the next 40 marker it will kick in again.