pt_mad
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Anyone know whether the top speed of the record run from Glasgow to Euston on 22nd September 2006 achieved in 3 hours 55 minutes 27 seconds was 125mph or higher?
The top speed would have been 125mph
Not necessarily, it's not unheard of for record runs to have speed restrictions relaxed (but I don't know for sure either way in this case).
Such as on 26 September 1991 when 91012 did the 393 miles between King's Cross and Edinburgh in 3 hours 29 minutes!...it's not unheard of for record runs to have speed restrictions relaxed...
Looking at aforementioned book, it is showing speeds such as 125/128 through Tring, though not sure exactly what this is denoting.
There is a note at the bottom though saying that unlike on previous record attempts, the permitted top speed could not be allowed due to TASS as it would have kicked in.
From what I understand though, it allows a small percentage overspeed so 128 is plausible, though not much, if anything, above that as the electronics then interject.
'Railway Magazine' did a 'cab ride' DVD which came with one of their magazines. According to the commentary it did reach 127 mph at one point but this was only very brief.
Such as on 26 September 1991 when 91012 did the 393 miles between King's Cross and Edinburgh in 3 hours 29 minutes!
I was on board, and managed to record the time to the nearest 1/100th of a second (somehow).
How fast would it be if the train was going at 140 mph or even travel via HS2?
Out of curiosity, how would you do that given there is no obvious start point or finish line? Was it doors locked in London to doors open in Glasgow? Was it wheels rolling in London to at a stand in Glasgow? Was it something else?
None stop at 140mph (assuming that it had a totally clear run and that it could actually do 140mph all the way) then it would have been just under three hours. I'm not sure what you mean by travelling via HS2, do you mean a 390 using HS2 (in which case no faster as a 390s top speed is 140) or do you mean using HS2 Classic Compatible stock (in which case the estimate is that when phase one is open London to Glasgow will be 4 hours).
BR proposed Euston to Glasgow journey times of 3 hours 52 minutes with 140mph running with APTs, so your calculations sound plausible.I did some guesswork and calculations on that, firstly, taking out the slight delays and minor signal checks we had in Scotland to give a 'perfect' run, and that would have shattered the record at 3hrs 49. Allowing 140 running south of Crewe, but including the minor checks would have given 3hrs 45 almost precisely, which might just make a 4hr dead scheduled service possible with stops at Carlisle and Preston only (both have speed restrictions anyway).
As I'm sure you are aware, there would never be a possibility of a 140mph start to stop average speed for a run limited to a 140mph maximum on the existing infrastructure, as it simply isn't possible to travel at 140mph all the way! It would probably be more realistic to consider the average speed of the 125mph Pendolino record run and to extrapolate a value from that: The stop to start average for the Pendolino record run was 102.25mph, which represent 81.8% of the 125mph maximum that was allowed.None stop at 140mph (assuming that it had a totally clear run and that it could actually do 140mph all the way) then it would have been just under three hours. I'm not sure what you mean by travelling via HS2, do you mean a 390 using HS2 (in which case no faster as a 390s top speed is 140) or do you mean using HS2 Classic Compatible stock (in which case the estimate is that when phase one is open London to Glasgow will be 4 hours).
As I'm sure you are aware, there would never be a possibility of a 140mph start to stop average speed for a run limited to a 140mph maximum on the existing infrastructure, as it simply isn't possible to travel at 140mph all the way!
I was on board, and managed to record the time to the nearest 1/100th of a second (somehow). Highest I timed was 129 mph between Acton Bridge and Winsford, but that's slightly suspect, being over seven miles without a proper timing point (I lost my place and don't know the line well). I also got 127 mph at Hemel Hempstead and 126 mph at Wolverton. All on my little stopwatch with a broken strap, and scribbled on a timing sheet we were handed out.
He's clearly not a physicist. A physicist would understand that just because the stopwatch has extra digits on the right doesn't mean it's actually measuring it to ±0.01 seconds. Human reaction times would make it ±1 second at least. Without the stopwatch being calibrated against a source based on an atomic clock (like a GPS receiver) beforehand, you can't even guarantee ±1 second precision.Out of curiosity, how would you do that given there is no obvious start point or finish line? Was it doors locked in London to doors open in Glasgow? Was it wheels rolling in London to at a stand in Glasgow? Was it something else?
He's clearly not a physicist. A physicist would understand that just because the stopwatch has extra digits on the right doesn't mean it's actually measuring it to ±0.01 seconds. Human reaction times would make it ±1 second at least. Without the stopwatch being calibrated against a source based on an atomic clock (like a GPS receiver) beforehand, you can't even guarantee ±1 second precision.
Likewise, measuring it "at a station" also impacts the precision of timing measurements - is the stopwatch clicked when the station comes into view, when you pass the start/middle/end of the platform, when you pass a sign on the platform or just some random point somewhere in the rough vicinity of the station? How precise is the distance given to the relevant point, is it just in miles and chains (i.e. ±20.12 metres) or is it accurate to the nearest metre? Is the exact track to be followed the source of distance measurements, or is it some approximate distance applied to all tracks on the route?
A physicist would understand that the various errors in precision (stopwatch calibration, inaccurate distances, inconsistent measurement points, reaction times, calculation mistakes such as imprecise conversion) are all multiplied together, not added. I've just done a few quick sums and found that you're dealing with potential errors of anywhere between 2-6% on a given interval from one station to the next, easily enough to account for pulling a figure like 129 mph out of the air.
Without having a motorsport-style transponder on the train and timing beacons placed at locations previously surveyed for the exact distance on the track path to be used, you can't expect to get anything within ±5 mph for the average speed over a given interval, especially not distances shorter than about 10 miles. His accuracy claims are not to be taken seriously.