Another S stock....(arrivals)

Not sure about humans, but 10 headless chickens were seen in a cab outside uxbridge last week.. ;D

MetControl, don't worry, it's only the forum's answer to Lord Haw-Haw making a fool of himself again.

MPH or years? ;D

Line speed on the met is as high as 60 in some places and if you class north of Amersham to Mantles wood where BR takes over as the met, there are 70mph linespeeds too!

That's on the shared section though isn't it.

Mmm I posted a rant about GPS Thingies in another A Stock Speed related thread recently - I've got a trace from my GPS thingy from when I left it in it's charger. It bobbled about over a 200m radius, not staying still for more than 10-20s at a time. Or what about the other time when I had it switched on on a flight to guernsey, the ATR72 I was on slowed from 350 to 45mph over the english channel, then sped back up again without any apparent change of altitude or engine setting. Or what about the 73TS doing 90mph on the Uxbridge branch... All using different GPS enabled devices. (2 Sat Navs and my Phone, respectively)

The simple fact is that it's not possible to obtain the level of accuracy needed to measure speed in a commercially available GPS device - the resolution allowed by the US government (who operate GPS) to comemrical GPS license holders simply isn't high enough for anything more than basic navigation / direction finding.

Truth be told what I believe is actually happening, and I completely understand it and have been guilty of it in the past, is a lot of enthusiasts are upset to see the A Stock go, and in their desire to see it off in a good light are exaggerating what it is doing in it's final months of service. Train drivers are far too professional to exceed restrictions that are in place for their saftey and the safety of the 7 or 8 hundred passengers on their train.

Show me some proper proof that an A Stock was doing 70mph (picture of a speedo reading, photographs time stampted against a known distance...) and I'll eat a printed out copy of this post. But as long GPS speed traces cannot be relied upon in a court of law I refuse to believe anyone posting such reports.

I have a Garmin Nuvi in my car and it's extremely accurate when measuring speed. I've monitored it on many journeys, some exceeding 300 miles, and it doesn't deviate by more than a mile per hour from the speed indicated on the car instruments. Maybe it's an exception to the rule.

I wouldn't suggest car instruments as a precision reference point - I've always read of car speedos being around +/- 5mph, sometimes more. Top end road testing certainly doesn't rely on the speedo when recording actual performance figures. Not sure but I think this may also have something to do with why there is a slight margin over the actual limit allowed before you get flashed by speed cameras.

More to the point, I'd imagine that occasionally a driver or two goes a bit too quick, but I'm sure it's not common. Having travelled more frequently on the Met in slightly faster days of yore, I find it noticeably slower on the Harrow-Finchley section these days (with less associated trampoline action on the inside of course). Disappointing - whilst the Met was basically my only route into/out of town back then it always stood out to me as it seemed so fast! Not so anymore.

What I don't get though is people moaning about 'EU, H&S blah blah' and all those tired old world's gone mad cliches when it comes to the A stock's speed. What has the EU got to do with the bogies breaking?! Surely the imposition of speed restrictions was engineering based (be it the fault of the train, or the track, doesn't matter) and not the result of maintenance cuts as has also been trotted out. As far as I gather from this forum, the maintenance cuts issues related to the stock have been in the very recent past, with replacement impending. The most readily apparent indication of this is that the trains are kept in a horrible looking state, which I must say is a bit rubbish. Impending replacement or not, I don't recall the corporate image-era LU ever running such shabby looking trains. It's like they've been made to look bad on purpose they look so scabby! I should like to see one returned to the original, venerable state.

I think that's enough of a debate about what A stocks are or are not doing in terms of speed. None of you are A stock drivers so that actually means you are not in a position to legally be in a train cab (train cabs are a safety critical environment and there are rules in place for a reason), nor are any of you in a position to be able to officially state the claims that have been made (ie, an LU employee) - in fact some of you are not even old enough to be employed by LU [assuming the age shown in your profiles is correct].

Furthermore, none of you are road trained on the Metropolitan line so what you think you may know about the line, including permitted line speeds and the capabilities of the rolling stocks, and what happens to be fact are likely to be two different things.

Contrary to what's been said in this thread, trains are driven to the supplied and fitted speed measuring device in the train cab, and in accordance with written instructions, signalling and signed speed limits. As per the rule book, train speeds are monitored using an approved and calibrated hand held speed gun of the type used by police officers. We do not rely on hand held GPS devices nor mobile phone apps.

As stated earlier in this thread, it will be locked soon. In fact I will be creating a new thread regarding S stock delivery and it's introduction to service as part of our tidying up of the Metropolitan and SSR areas of the forum later on tonight - you can have a bit of grace until then if you wish to post a response.....

I know what you mean, but the indicated speed on the Garmin is the same as that on the car. In fact it's the same on my wife's car and another vehicle I use from time to time as well as my mate's car where I've also used it. This is what leads me to believe it's accurate. The chances of all four vehicles and the Garmin being wrong to the same margins are slim. I do suspect however that on a train with a powerful electrical field not far below your feet, or above your head for that matter, all sorts of discrepancies could be induced into the device.

Has anyone tried the same experiment on a DMU with no overhead or live rail?

plus 5 mph yes, but not minus.


Type approval requirements are that the indicated speed must never be less than the actual speed (i.e. it should not be possible to go faster than the indicated speedometer reading) and not more than 110 percent of the true speed plus 4 km/h

Thus at a true 60kph the speedo must read somewhere between 60 and 70kph.

Ah OK I am quite happy to be corrected on that; by no means knew the ins and outs I just knew speedos aren't generally bang on!

Re the GPS though, yes, I would imagine that in a car (certainly in my experience even though I've never owned a sat nav) they are pretty damned close, was just making the point that this doesn't qualify them as any more or less useful for what was being discussed.... Which we agree on anyway... This really has got tangenty; night!

ps certainly didn't mean to contribute to the more dimly viewed elements of this thread - I think my comments were fairly uncontroversial and quite clearly the observations of a passenger, nothing more!