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GPS (basically) constantly use the time difference in signals from multiple satellites to calculate location and speed over the earth’s surface.
Nothing to do with distance covered!
But speed is distance/time. Doesn't it work on the basis that you were in position A 1 second ago, you're now in position B. A and B are 10 metres apart therefore you're traveling at 10m/s or 22.4mph.
Apparently 10,000 drivers are over 12 points but aren’t banned due to the “hardship” exemption.
That's 10,000 people who should have thought a bit harder about their actions and the consequences. If you need your licence then maybe drive like it's important to you that you keep it.
But speed is distance/time. Doesn’t it work on the basis that you were in position A 1 second ago, you’re now in position B. A and B are 10 metres apart therefore you’re traveling at 10m/s or 22.4mph.
Serious thread derail but in the old days GPS units used to use either a differential or a doppler method of calculating speed. Differential does indeed calculate the distance between two positions over a given period. The doppler method is totally different and works on the satellite signals being 'compressed' or 'stretched' by your velocity taking you further away or closer. Use the change to the signal from multiple satellites to calculate your velocity in 3D.
I've no idea how modern units work now. I'd assume the doppler method as it is more accurate (or has less lag) but GPS units are cheap as now and put into stuff that does other stuff so maybe the cheap ones use differential. No idea, that geek fascination is no longer something that I follow closely.
8 hours, nearly 40 posts, yet nobody has found a way to blame cyclists. Come on STWers, you’re slipping.
Good point. Surely the OP had to speed up, and justifiably so, to safely overtake a group of roadies that were holding him up
Perhaps the OP would have been driving more carefully if cyclists were allowed on motorways.
That’s 10,000 people who should have thought a bit harder about their actions and the consequences.
It's pretty easy to get 12 points on Smart Motorways these days, you could probably do it in a couple of miles if you really weren't paying attention. Personally I don't think everyone who gets a speeding fine is automatically some sort of danger to society, You could go through "many" of the 60 limits at 70 pretty safely, and you'd rack up 3 points at each one. I used to do a shit tonne of driving, and compared to town and local driving the motorways are much safer, but it's easier to fall foul of rules that are applied more often and more rigorously. We're none of us perfect.
On a speed awareness course I went on I was told that the threshold for a ticket varied widely across the country, with some counties having a zero tolerance (or close to) policy, while others were still at the old 10%+x rule of thumb. That's the point at which you get written to, for course, points or whatever, not the point beyond which a course is no longer offered.
Our current cars both read over by only 1-2mph at motorway speed. Assuming comparing with GPS reading on Google maps is a reasonable measurement device.
Amazing how many people don't realise that the smart motorway limits are real limits. The old yellow ones are "advisory" though. It seems to me that the issue with these signs crying wolf is quite prevalent on the advisory signs but the smart motorway ones seem to me to be generally justified, and also pretty effective in maintaining a solid speed. I rather like them (even though I've fallen foul of them enough to have been on a course, obvs).
Yes, I was doing in the low 70's to account for the speedometre overreading and was only intending to do 70mph.
Not reacting to the Smart Motorway's variable speed restriction in time was a mistake. The 50 was due to a lane closure ahead, but there was no evidence of any cones in sight.
It is annoying that I get caught just for a mistake when there are people deliberately speeding all the time. Frequently see people driving on motorways in the 80's and 90's.
In my job I frequently have to use Taxis and it is common to see them speeding all the time.
“Wah! You should be watching the speed limit any way! Etc”.
Yes. But in a busy, dynamic, heavy traffic environment, giving me better cues means i can spend more time texting.
Nice. You had me up to the last sentence. 🤣
it is annoying that I get caught just for a mistake
You didn't make a mistake. You were, by your own admission, already knowingly speeding in the 70 limit. I've got no sympathy for you I'm afraid.
Is it a £100 fine and 3 penalty points or is it the Band A, B & C System?
If the latter I would be placed into Band B and fined approximately one weeks salary before tax. This is currently £1100. So way more serious than the more usual £100 fine.
However, I've only heard that the Band system only comes into place if I receive a court summons ? I've also heard that a court summons is rare for getting caught by a speed camera ?
You could go through “many” of the 60 limits at 70 pretty safely
You can "safely" do 100 in a 30 if you are lucky, but just because you can doesn't mean that you should.
There needs to a simple, short ban system in place for first time 12 point offenders. Just a month without a car, no exemptions, to remind people how much easier modern life is when you can drive. Make it illegal to lose your job for that first month ban.
Suggested
Mandatory
The key is the red circle
I can only assume the ones on the M6 heading towards the M5 don't work as I regularly get overtaken at a fair old speed while I do 60 through there as indicated by the gantry signs.
Yet all of the cars vans etc that overtake me are local at least from the signage on the vans or the reg plates, locals must have more info than me?
You can “safely” do 100 in a 30 if you are lucky, but just because you can doesn’t mean that you should.
Yeah, I don't disagree, I'm not saying that one "should" do those things, I'm saying it's easier to get caught now in a system that's widely applied and is still misunderstood by lots of folk. I accept that folk who drive on M-ways should know all about variable speed, totally, but back here in the real world, many folk don't and it's easy to rack up points.
Not making a moral judgment, just saying it's easy to do.
Recent 10% +2 speed awareness course attendee here (well, it was face to face, so probably 2019)... 83 in a 70 so not sure how I got the course... anyway the big take away from me, any speed restriction with a red circle around it (on a gantry/screen or otherwise) is a legal requirement and can be enforced. Any orange ones are advisory, but you'll get the book thrown out you for driving dangerously/carelessly if you are involved in an accident where you were found above the advised/cautionary limit.
Not reacting to the Smart Motorway’s variable speed restriction in time was a mistake. The 50 was due to a lane closure ahead, but there was no evidence of any cones in sight.
Well, maybe you've learned a valuable lesson, there. In case you didn't know, if a lane closure is indicated, you can get ticketed if you pass a gantry and you're still in the lane with the big red X marked above it.
It is annoying that I get caught just for a mistake when there are people deliberately speeding all the time. Frequently see people driving on motorways in the 80’s and 90’s.
Ah - maybe that lesson's been wasted, then. You were deliberately speeding yourself, no?
No it was just a mistake. I never knew much about Smart Motorways until now, and never realised that the reduced speeds were so mandatory.
I never thought they were any more serious than the advisory limits. I think it's because Smart motorways are a relatively new thing and I never really researched what they are until now.
Still wondering what the answer is to this ? As there is a huge difference between a £100 fine and getting charged around 1 weeks salary before tax, and I can't find out which one will apply.
Isn’t that just saying gps calculates speed is calculated from measuring the distance then divide by by time?
The satellites have atomic clocks on board.
There's then some clever algorithm stuff going on which results in a mix of known and predicted speed, smoothed over a (very short) time period. It's not instantaneous (at least, not on consumer units, military and aviation stuff works to a higher standard and has multiple independent backups), part of it is predicted based on "well you were doing 50mph 1 second ago so it's fairly likely your speed now will be about the same" and part of it is measured and the two combined.
https://en.wikipedia.org/wiki/Kalman_filter
You can do speed between known points. There was an interesting documentary on F1 GPS systems and how they calculate the position and speed of cars to such high accuracy and it's based on having exactly plotted points on the tracks and running the info through those known static points. Does away with a lot of the shift error from changing signals as satellites appear and disappear from view.
If the latter I would be placed into Band B and fined approximately one weeks salary before tax. This is currently £1100. So way more serious than the more usual £100 fine.
Worst build up to a stealth boast. Ever.
You've admitted knowingly going over 70.
You've admitted not understanding traffic signage.
Prepare for the worst, hope for the best. And stop digging.
Not reacting to the Smart Motorway’s variable speed restriction in time was a mistake. The 50 was due to a lane closure ahead, but there was no evidence of any cones in sight.
You won't get flashed at the first gantry either so you were already in a 60 or 50mph zone (or driving a vehicle which "looks" like the nsl isn't 70 on a motorway). That or you didn't get flashed and someone else did
I never knew much about Smart Motorways until now, and never realised that the reduced speeds were so mandatory.
Not knowing the law isn't a "mistake", and new thing? They've been in place for 15 years.
They’ve been in place for 15 years.
Sure, but lots and lots of folks don't do much M-Way driving at all. Some maybe just once or twice a year when they go on Holidays. For those folks they may never have seen a Smart Motorway, or paid any attention to how they work. You might think that's daft, but it's more common than you think.
MrOvershoot
Full Member
I can only assume the ones on the M6 heading towards the M5 don’t work as I regularly get overtaken at a fair old speed while I do 60 through there as indicated by the gantry signs.Yet all of the cars vans etc that overtake me are local at least from the signage on the vans or the reg plates, locals must have more info than me?
The newer cameras are no longer on the gantry behind the sign, they are on a platform to the side of the gantry, usually two yellow cameras, and only on every few gantries, so those who know the stretch of road tend to know they can speed through the first, second, third, but slow down on the fourth or whatever.
We have the same in Bristol, they updated them to the Hadec 3 cameras and they're more obvious to see what gantries are actually monitoring the speed of the traffic, i find this causes more issues than it removes, as you have idiots overtaking and undertaking you at speed whilst you're doing the variable limit, and of course around the interchange for Bristol this means folk trying to get back into the right lane having to avoid this.
I never knew much about Smart Motorways until now, and never realised that the reduced speeds were so mandatory.
I don't think they are any more or less mandatory than any other traffic sign inside a red circle.
If the latter I would be placed into Band B and fined approximately one weeks salary before tax. This is currently £1100. So way more serious than the more usual £100 fine.
What a shame
Sure, but lots and lots of folks don’t do much M-Way driving at all. Some maybe just once or twice a year when they go on Holidays. For those folks they may never have seen a Smart Motorway, or paid any attention to how they work. You might think that’s daft, but it’s more common than you think
But you'd think those same people who only ever see normal signs showing speed limits might be less inclined to think they're just some sort of decoration to be ignored because they don't have the experience to think there are things like advisory limits, which you only see on motorways or big A roads.
For those folks they may never have seen a Smart Motorway, or paid any attention to how they work. You might think that’s daft, but it’s more common than you think.
But surely they have seen a speed limit sign before and know what that means?...
I probably fall into that category - I drive past Birmingham maybe once or twice a year, but the most confusing thing as I toodle along at 50 was the sheer number of repmobiles and local vans blatting past me at 90 regardless. Do they know something we don't?
Not really a stealth boost ?
That salary after tax, national insurance, etc is not really a lot
But it's a big fine because it is before tax, compared to the more usual £100.
I never knew SMART Motorways have been in place for 15 years.
I try to avoid driving where necessary. I guess I've just very rarely ever come across them when they've actually been in use.
It’s quite a new thing this SMART Motorways system where the speed cameras also adjust to the variable speed limits and these go off instantly if one doesn’t slow down to the new variable speed straight away.
As others have said, they're far from new. And the cameras don't go off "instantly" - there's something like a minute of grace.
Does it matter whether you've done much driving at all, or whether you've been on a Smart Motorway? Or whether it's a new car you're not used to driving, or whether everyone else was doing that speed, or whether the sun was in your eyes, or you were late for an appointment, or, or, or...?
If I'm driving on a motorway it's because I've passed a test to be given a licence to drive. Keeping that licence is dependent on me obeying the law. It's a privilege, not a right and it can be taken away. The law says if there's a sign next to or above the road with a speed limit on it, that's the _maximum_ speed I'm allowed to drive. It's my responsibility to look out for those signs (so "I didn't see it" is an admission of guilt, not an excuse) and it's my responsibility to be in control of my car at all times.
Therefore, if I'm driving faster than the speed limit, I'm breaking the law. It's not complicated, if I had a driving instructor in the car and my licence depended on it I'd "remember" to drive within the law.
Anything else is an excuse and every single driver knows this.
Yes I know I sound like I'm on a high horse (2 pages in) but I'm [b]not[/b] judging here, just trying to point out the logic of the situation. Speed limits have always meant the same thing.
I'd rather travel at 80+ than 70 on a clear motorway if I can, and I do if I think I won't get caught - but I know that when I do I'm breaking the law. Of course, like everyone else I try not to get caught so I slow down if there are yellow boxes around. If I don't see, or ignore, a speed limit sign, I know I'm breaking the law. And that's my choice, and it's every driver's choice whether they acknowledge it or not, and I have to deal with the consequences if I get caught.
I never knew SMART Motorways have been in place for 15 years.
I try to avoid driving where necessary.
Yet you "knew" the normal fine is £100, which most people wouldn't have a clue about. Certainly not people who rarely drive.
You "knew" a lane closure would have cones.
You knew what the sign meant.
You "know" your speedo will over read.
It seems the only thing you didn't know is that you might be caught, and strangely enough, that expectation is usually a direct result of not being caught before.
But surely they have seen a speed limit sign before and know what that means?…
Hold onto your hat, you're in for a surprise. There's lots of folk for whom the idea that they drive anywhere other than about 35-ish in town, about 45-ish on country roads and about 65-70-ish on motorways is pretty much default. Asking those folks to pay any more attention to it once they're actually on a M-way is asking waaay too much of them. It's one of the reason (I think at least) M-ways are safer, as well as all the well known studies, they tend to be self selecting, ie some folk just won't use them at all as they just can't cope
If those folks find themselves on a m-way for any reason, mostly they're using all their brains either 1. trying v hard not to have a meltdown, and 2. concentrating so hard on not crashing into some-one else, or being crashed into, there's no more space for anything else, road signs included.
That salary after tax, national insurance, etc is not really a lot
£57k is a good salary by most people's standards. Around double the average.
Saying it's "not a lot" is crazy.
I did a speed awareness course after being camera-vanned doing 61 in a 50 (bang to rights - I was overtaking a caravan at the last point before 10 miles of twisty road)
The North Yorkshire course guys said the upper limit for being offered the course was 64 in a 50. May be different for smart motorways but maybe not.
But you’d think those same people who only ever see normal signs showing speed limits might be less inclined to think they’re just some sort of decoration to be ignored because they don’t have the experience to think there are things like advisory limits, which you only see on motorways or big A roads.
I’d fall into this category..no idea what a smart motorway even is! Do we have them in Scotland? just assumed when I see a number flash above a motorway then that’s the limit that is mandatory
As an aside however, 2 weeks wages before tax seems pretty harsh for speeding on a motorway. I’d probably get less of a fine for assaulting someone which seems ridiculous
I’d fall into this category..no idea what a smart motorway even is! Do we have them in Scotland? just assumed when I see a number flash above a motorway then that’s the limit that is mandatory
Yeah, that's the thing for me. If you don't know, you should be on the side of caution.
£57k is a good salary by most people’s standards. Around double the average.
Indeed, a gross salary of £57k is borderline top 10% of UK earners.
Especially when it's just from failing to react to a variable speed limit in time.
Getting fined for doing 80MPH + on a motorway is understandable, it is clearly deliberate
But not reacting to a variable speed limit in time, when the motorway looks clear as far as I could see, it's just a mistake.
£100 would be reasonable, but one or two weeks salary is atrocious
As an aside however, 2 weeks wages before tax seems pretty harsh for speeding on a motorway. I’d probably get less of a fine for assaulting someone which seems ridiculous
It's about the potential to do harm. Most motorway speeding (and other bad driving) goes by without causing more than passive aggressive tutting but when there are accidents on Motorways fatalities are common.
But not reacting to a variable speed limit in time, when the motorway looks clear as far as I could see, it’s just a mistake.
You've got at least a full minute (more than a mile at 74mph), how much time do you need?
No it was just a mistake. I never knew much about Smart Motorways until now, and never realised that the reduced speeds were so mandatory. I never thought they were any more serious than the advisory limits.
And what made you happy to roll past what you thought was an advisory 50 at an indicated 74, amongst traffic that presumably wasn't getting flashed?
Is it definitely a multiple of gross weekly income?
That would seem a little harsh to higher earners, as it's a higher percentage of take home pay (i.e. it's more weeks of actual take home pay for a higher rate taxpayer than for a lower rate taxpayer).
If you earn 57k damn right it should be more than £100. How the hell would that be fair. Your on triple my and many others salary so how would it be any kind of incentive for you to slow down if it's less than a singular days wages