Re: [LEAPSECS] No leapseconds on trains
On 20 Nov 2011, at 1138, Poul-Henning Kamp wrote: > In message <4528db27-ce6e-4d72-84b3-72d3ef210...@batten.eu.org>, Ian Batten > wri > tes: > >> Anyway, the average freight train in the USA is 6500 feet long (ie >> substantially over a mile) and travels at an average of around >> 20mph, or at most 30mph. > > I would expect the relevant technical case to be high-speed passenger > trains, travelling at up to 90m/s and where the entire train can > pass over a point on the track in as little as two and a half second. Which isn't a use-case for passing times being measured manually at manual signal boxes and manually written onto paper sheets for manual analysis, of course. ian ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] No leapseconds on trains
Poul-Henning Kamp said: > For further reading, I can recommend the ERTMS(2) family of standards, > they integrate all trains in a control-domain in a wireless network > and does away with red/green lamps. When it works. The trial setup on the Cambrian lines doesn't seem to be going well - it can't cope with two trains requesting authority from the same track section in close succession, which is a problem on a line that divides trains! -- Clive D.W. Feather | If you lie to the compiler, Email: cl...@davros.org | it will get its revenge. Web: http://www.davros.org | - Henry Spencer Mobile: +44 7973 377646 ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] No leapseconds on trains
Ian Batten said: >>> This wasn't the timetable. Its main purpose, as I understood it, was to >>> provide a record of where trains were, or where the dispatchers thought >>> they were, in the event of an accident. >> Hmm, they may well be logging each track circuit transition > Track circuits? In manually-signalled USA? The USA had track circuits well before the UK. Read Rolt. I thought it was fairly usual to track circuit at least sections of lines - for example, in remote areas signals were approach-lit to save battery life, so that implies several TCs in rear of the signal. > Anyway, the average freight train in the USA is 6500 feet long (ie > substantially over a mile) and travels at an average of around 20mph, or at > most 30mph. So it takes around two minutes to pass a point. Timing that to > a precision of a second seems a excessive. True. -- Clive D.W. Feather | If you lie to the compiler, Email: cl...@davros.org | it will get its revenge. Web: http://www.davros.org | - Henry Spencer Mobile: +44 7973 377646 ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] No leapseconds on trains
In message <4528db27-ce6e-4d72-84b3-72d3ef210...@batten.eu.org>, Ian Batten wri tes: >Anyway, the average freight train in the USA is 6500 feet long (ie >substantially over a mile) and travels at an average of around >20mph, or at most 30mph. I would expect the relevant technical case to be high-speed passenger trains, travelling at up to 90m/s and where the entire train can pass over a point on the track in as little as two and a half second. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
Re: [LEAPSECS] No leapseconds on trains
On 18 Nov 2011, at 16:48, Clive D.W. Feather wrote: > Paul J. Ste. Marie said: >>> Hmm. In the UK the working timetable (not the public one) is written to a >>> precision of half a minute. >> This wasn't the timetable. Its main purpose, as I understood it, was to >> provide a record of where trains were, or where the dispatchers thought they >> were, in the event of an accident. > > Okay. > >> The logged locations weren't stops on the lines. > > Hmm, they may well be logging each track circuit transition Track circuits? In manually-signalled USA? Anyway, the average freight train in the USA is 6500 feet long (ie substantially over a mile) and travels at an average of around 20mph, or at most 30mph. So it takes around two minutes to pass a point. Timing that to a precision of a second seems a excessive. Each vehicle is of the order 20m long, so at those sorts of speed is going to take over a second to pass. ian ___ LEAPSECS mailing list LEAPSECS@leapsecond.com http://six.pairlist.net/mailman/listinfo/leapsecs
