Speed camera detectors/laser warnings
Posted by: Jonathan Gorse on 02 January 2008
Chaps,
I'm contemplating investing in some electronics for the car to assist me with a longish commute in reducing the risk of being caught speeding.
Basically I will be commuting from Surrey to Birmingham Airport - usually outside peak hours and wondered if anyone could advise on the best system to:
Provide notification of traffic hold-ups and recommend diversion routings
Warn of speed cameras
Warn of laser type speed traps
In was in Halfords the other day and they indicated that the laser warning devices were about to become illegal next month so maybe a good time to get in quick!
Leaving aside the moral debate around speeding I will often be commuting at 4am when there's hardly any other bugger around and so am rather keen to find a way to keep up a steady 80 or 90 while minimising the risk of accumulating points!
Advice?
Jonathan
Posted on: 07 January 2008 by Paul Hutchings
FWIW speeding is basically an absolute offence i.e. get caught doing 71mph in a 70mph and they could prosecute for it, though of course due to the fact the courts would be flooded and speedometers have a degree of error most areas follow/interpret the ACPO guidelines.
Your car speedo is legally only allowed to over-read and by up to 10% and that's at the time of manufacture.
Can't help but think technology isn't the answer, keeping your eyes open and wits about you is the best answer.
Posted on: 17 January 2008 by AV@naim
quote:
Originally posted by living in lancs yearning for yorks:
Nobody's bothered to mention that the indicated speed per your speedo is usually inaccurate - my last couple of cars have exaggerated the true speed by around 7%. (This is identifiable by using a GPS sat nav or camera database such as Road Angel.) Up to 10% exaggeration is legal I think. So 80 indicated is actually nearer 74
A GPS unit is very helpful in indicating precisely what speed you are travelling at - can't recommend any current models as I don't have one, although have in past used Road Angel
The "10% + 2mph" is I understand a recommended guideline, so not any kind of hard and fast rule. The motorways are by far the safest roads and exceeding the limit on them is not the heinous activity some seem to consider it to be. The limit was only introduced (by Barbara Castle I think) as a temporary measure during the 70's oil crisis and has no scientific basis
30 limits however are massively more important and sticking to them is a seriously good idea
here, here!, although...and being picky, GPS should NOT be used as an "accurate" measure of position let alone speed. Its only accurate to a percentage (usually 95%) in a given period of time, dependant on how many birds you are actually locked on to, the ionoshpere that day and multipath errors.
Why do you think we still are not landing planes automatically with GPS...
My personal pref is a camera database on a GPS device
Posted on: 17 January 2008 by Jim Lawson
quote:
Its only accurate to a percentage (usually 95%) in a given period of time, dependent on how many birds you are actually locked on to, the ionosphere that day and multi path errors.
Excellent point.
Jim
Posted on: 21 January 2008 by living in lancs yearning for yorks
quote:
Originally posted by AV@naim:
quote:
Originally posted by living in lancs yearning for yorks:
Nobody's bothered to mention that the indicated speed per your speedo is usually inaccurate - my last couple of cars have exaggerated the true speed by around 7%. (This is identifiable by using a GPS sat nav or camera database such as Road Angel.) Up to 10% exaggeration is legal I think. So 80 indicated is actually nearer 74
A GPS unit is very helpful in indicating precisely what speed you are travelling at - can't recommend any current models as I don't have one, although have in past used Road Angel
The "10% + 2mph" is I understand a recommended guideline, so not any kind of hard and fast rule. The motorways are by far the safest roads and exceeding the limit on them is not the heinous activity some seem to consider it to be. The limit was only introduced (by Barbara Castle I think) as a temporary measure during the 70's oil crisis and has no scientific basis
30 limits however are massively more important and sticking to them is a seriously good idea
here, here!, although...and being picky, GPS should NOT be used as an "accurate" measure of position let alone speed. Its only accurate to a percentage (usually 95%) in a given period of time, dependant on how many birds you are actually locked on to, the ionoshpere that day and multipath errors.
Why do you think we still are not landing planes automatically with GPS...
My personal pref is a camera database on a GPS device
Still more accurate thsan my car speedo though
Posted on: 21 January 2008 by John Channing
quote:
Its only accurate to a percentage (usually 95%) in a given period of time, dependant on how many birds you are actually locked on to, the ionoshpere that day and multipath errors.
The accuracy is actually better than that at less than +/-1% error.
quote:
Why do you think we still are not landing planes automatically with GPS...
Probably because the system is operated by the American millitary and therefore we don't get full resolution positional triangulation.
John
Posted on: 21 January 2008 by prowla
90 on a clear motorway is perfectly safe, and at that speed a crash is pure chance anyway.
The speed limits were defined by a combination of the 70s oil crisis and the manoevurability of a Morris Minor; a modern car is so much better than what was available back then.
The zealots who claim a moral superiority by saying anybody who exceeds the speed limit is a criminal have closed minds.
However, there is also a choice as to whether you choose to obey the law of the land or not.
That is both a matter of conscience, and a rationalisation of what it means to be a member of society.
(Note that I also believe that 30 may be too high on urban roads, and certainly near schools and suchlike - the American dead slow limit near schools is something we should consider.)
Regarding accuracy, those local signs that clock your speed and flash up a warning 30/whatever are surprisingly precise, almost overly so!
Posted on: 21 January 2008 by Andy Kirby
Funny you should comment on speedo accuracy, here in the US I find my cars are pretty much spot on, +/- 1% whilst motorcycles are always showing +10%, no idea why??
I use a couple of GPS's and a Bel radar detector whilst out riding in various events, LD Rallies etc and the 'laser' feature on the RD is simply a 'ticket indicator'. You may get lucky from time to time and get a stray hit, plus the cops here do seem to target the idiots weaving from lane to lane, undertaking etc. but on the whole it's a policeman pointing his 'gun' at you and reading off exactly how fast you are moving.
The best protection here is to use a CB, as long as there are plenty of truckers around you'll know exactly where the 'smokies' are, it's illegal for a commercial vehicle driver to posses a radar detector so they have a pretty well developed 'system'. On the whole though I stick to '10 over' with the cruise control firmly set and rarely have a problem.
As ever YMMV
Andy
Posted on: 21 January 2008 by rackkit
quote:
Originally posted by GFFJ:
The last time I listened to the radio in the car was one summer Saturday in 1982, when there was deferred relay of a Wagner opera from Bayreuth, and it has started to rain. Apparently auto-pilot had put the wipers on, but I failed to realise how slippery the road was. I spun the car on a quite sharp bend [on the A 49 going towards Shrewsbury from Ludlow] without hitting anything, but facing the wrong way round exactly on the other side of the road facing Ludlow again. Quite a moment, and in a Renault 12, quite a chance I could have tipped the car over.
I have never listened to music in a car since!
ATB from George
Now that's what i'd call dangerous.
Posted on: 22 January 2008 by Derek Wright
Re Satnav speed accuracy
I have found that the offset between the SatNav indicated speed and the speedo indicated speed remains consistent for a given car, set of wheel/tyres over the period of ownership of the car. So while there is the concerns re accuracy of Satnav speed it does have a constant error rather than a variable error. Now as to which is more accurate - car or Satnav - I think Satnav - well it gives me an extra 2mph.
Posted on: 22 January 2008 by Derek Wright
And to go back to Jonathan's original question - he could adopt the alleged technique of the truck drivers in a nearby nation - they drive with the rhs wheels on the rumble stripped white line of the motorway sensing the noise/vibration. This enables them to read, play games watch TV while using cruise control to maintain speed. If the vibration ceases they have to look up from whatever thy are doing and correct the steering.
Posted on: 22 January 2008 by u5227470736789439
Satnat gave me a consistent 3 mph more on two occasions in the old Volvo. When the speedo read 30 I was doing 27 and at 60 it gave 57 etc.
Nice to now the needle can be just above the line and still be legal for any given speed limit.
A funny 1948 Autocar review of the MO Series Morris Oxford tells a funny story. On the timed speed runs the car achieved its claimed top speed of 67 mph half a dozen times, but the speedo was reading just shy of 80! I guess MO drivers were not too worried by the speed limits in the rural setting! Also interesting is that 0 to 50 [not 60] acceleration was tested at 48 seconds! My kind of car! Especially as once you had found top gear there was little need to change again, except to restart after a junction or whatever! Column shift as well and a proper six seater. Two bench seats!
George
Posted on: 22 January 2008 by domfjbrown
quote:
Originally posted by prowla:
90 on a clear motorway is perfectly safe, and at that speed a crash is pure chance anyway.
The speed limits were defined by a combination of the 70s oil crisis and the manoevurability of a Morris Minor; a modern car is so much better than what was available back then.
Reaction times are still the same as in the 70s though.
Honestly, you lot should think yourself lucky you CAN drive - even at a measly 70 mph.
No sitting around on cold railway platforms waiting for late and overpriced trains for you.
Think yourselves lucky you've got enough eyesight to drive!
Gripe over. ...until the next tosspot tries to run me over on a pelican when the green man's lit... No "safety cameras" THERE I notice!
I can see the point re >70mph at 4am though.
Posted on: 22 January 2008 by Duncan Fullerton
quote:
Originally posted by AV@naim:
Why do you think we still are not landing planes automatically with GPS...
We will be shortly. Well the Yanks will be anyway, as usual the CAA are about a decade behind. The FAA expect that semi-precision (LPV) approaches for GPS will outnumber ILS approaches in 2008. See
here for numbers. Also approval for the first CAT III GPS approach (in Memphis) is expected later this year.
Personally I'd be lost (!!) without my GPS when flying and its accuracy is way better than the 95% you proffer. Appreciate the bit about "birds in sight", but what is your source for that number?
Duncan
Posted on: 22 January 2008 by Jonathan Gorse
Well chaps, this has turned into quite an interesting thread and you'll no doubt be interested to hear I have ordered a Garmin 710 which has all the bells and whistles. I was tempted by other models like the MyMichelin 970X and some of the Sony models but in the end after being a Garmin user for so long (in the air) and finding their after sales support excellent I decided to stay loyal to them.
The MyMichelin at £120 ish does everything the £225 Garmin does but the difference is that in 5 years time I know Garmin will still be supporting the product. Nowadays I always buy from manufacturers who stand behind their product.
Jonathan
Posted on: 24 January 2008 by Don Atkinson
quote:
Also approval for the first CAT III GPS approach (in Memphis) is expected later this year.
Duncan, is that CAT IIIa or b? Will the associated a/c equipment generally be fail passive or fail operational? and will the flare commands and auto-throttle commands be GPS inspired or continue to be radio-altimeter inspired?
Cheers
Don
Posted on: 28 January 2008 by Duncan Fullerton
quote:
Originally posted by Don Atkinson:
Duncan, is that CAT IIIa or b? Will the associated a/c equipment generally be fail passive or fail operational? and will the flare commands and auto-throttle commands be GPS inspired or continue to be radio-altimeter inspired?
No idea Don. I don't aspire to flying Cat anything equipped aircraft! VMC 4ME! I mention the point to demonstrate that if the FAA think it's accurate enough for CatIII approaches then it's good enough for most other uses. There's tons of FAA stuff out there on this if you care to Google it.
As for the other stuff; if the ILS currently handles the approach and the RA handles the flare/AT, then I suspect (but don't know) that GPS will take over just the role of the ILS. That would seem to make sense.
The neat bit about this is that if it works(!) then having to space out approaches in CatIII conditions so as to clear the landed craft from the "interference zone" of the LOC will be a thing of the past.
Duncan
Posted on: 28 January 2008 by Jonathan Gorse
Don,
I'm afraid I can't answer your query either but the latest info I have is from this presentation:
http://www.navcen.uscg.gov/cgsic/meetings/47thMeeting/%...AS-LAAS-CGSIC-07.pdfIn essence the FAA aren't being too specific about anything beyond Cat 1, although they do seem to intend Cat 3a/b/c operation in the longer term, albeit some years out beyond 2014.
If they intend to implement a LAAS based Cat 3b or c capability then under current regulations it must be fail operational.
In any event I would I would be surprised if they switch off ILS systems very quickly even when LAAS comes in, even if the ILS is only in place as a fallback! Amazing to think ILS was invented back in the 1930's and yet we're struggling to figure out how to better it!
Brg,
Jonathan
Posted on: 28 January 2008 by Don Atkinson
Thanks Duncan, thanks Jonathan,
I had to struggle to read the link posted by Jonathan (limitations of my dial-up web service), but I have got the gist of the presentation. many thanks.
Unfortunately, my main recollection of the presentation is dominated by the thought that if they can't get the date on the front cover right, what else can't they get right?
Grossly unfair comment, but.........
Cheers
Don
Posted on: 28 January 2008 by Martin D
"Hope you get put away"
from mr d
and
"perception of revenue raising....."
from mr c
come off it guys, in 5% of accidents is speed a cause so get your heads out of the sand and lets concentrate on the other 95% that DO cause the problems - I'm all for that, but that would mean variable limits with a realistic max that could be at least 85 in some circumstances. I regularly drive early down in the south west and on the continent where you could cruise at 90 no problem and see the next vehicle on the horizon, and more traffic cops which I'm all in favor of not the pathetic traffic wombles appearing everywhere. Either the above or the chance to turn into a revenue raiser err I think I know what's happening
Posted on: 28 January 2008 by Duncan Fullerton
Don,
Interesting to think that in todays' higher levels of expectations that a small mistake in a presentation may cause consternation when we remember that in an older world the ADF was the bees knees as far as Navaids went!
Hadn't realised the ILS was so old BTW, however I remember from my PPL that that the Yanks invented the VOR yonks ago. For GA we haven't come a long way since it seems ... and I especially include the engines in that.
Jonathan ... Don's points about fail passive/fail operational (and I'm not sure what that really means), maybe you can explain ... is that something mandated by various authorities, or is that a matter of implementation by the aircraft manufacturers?
Duncan
Posted on: 29 January 2008 by Don Atkinson
quote:
Don's points about fail passive/fail operational (and I'm not sure what that really means),
It basically boils down to whether you have three auto pilots or two auto pilots.
With three, and one fails, you can continue the approach with the other two auto pilots. With two and one fails, you have to go around and basically do a manual ILS.
To a certain extent, what you do (or what the system does), depends on when a failure occurs.
Obviously landing in Cat IIIc (zero decision height and zero RVR) doesn't give you (m)any options, so fail-operational makes good sense.
Cheers
Don
PS I'll now go away and read my teaching notes before Jonathan, with his more recent operational experience, corrects me.
