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Post by programmes1 on Jun 8, 2007 15:45:56 GMT
Does anyone know what the capacity of each line is for TPH to actual capacity by the signalling system there does not appear to be any documentation. There is a document on the web for New York 1950's.
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Post by Deleted on Jun 8, 2007 17:19:36 GMT
well i believe the central line has the most capacity but couldnt tell you how many trains per hour it is capable of and this only involves ATO mode
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Post by citysig on Jun 8, 2007 17:39:25 GMT
I am not aware of any official figures, but on the Met, H&C and Circle we are generally capable of running 30-36tph in each direction between Baker Street and Liverpool Street - provided of course, there are no hold-ups.
During the peaks when this kind of service is run, there are very few "gaps" in which to slot any additional trains, so therefore you could say that the figure is both our TPH and signal capacity.
Based on experience, Hammersmith to Praed Street junction could handle 20-25tph and Praed Street though to Liverpool Street 30-36tph.
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Post by Deleted on Jun 8, 2007 18:17:08 GMT
well i believe the central line has the most capacity but couldnt tell you how many trains per hour it is capable of and this only involves ATO mode Looking at WTT64, the official maximum is 30 TPH, from White City to Leytonstone in the peaks. This is dependant on which peak (AM or PM) and the direction of travel. |
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Post by Deleted on Jun 8, 2007 19:33:25 GMT
Train every two mins White City - Leytonstone... so 30tph! Just seen the post made by Alex!  |
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Post by tubeprune on Jun 8, 2007 20:57:47 GMT
Does anyone know what the capacity of each line is for TPH to actual capacity by the signalling system there does not appear to be any documentation. The setup on each line is different. If you take the Victoria Line as an example, since it is well documented, the original signalling was designed on an 82 sec full speed headway - this means trains running at normal line speed without station stops. With station stop of 30 secs, the headway becomes 112 secs. A 10% margin gives the operating headway of 120 secs. Average dwell times have crept up over the years and now all they can manage is 126.5 secs = 28.5 tph. The other limiting factor is the termini. Brixton is limited to 109 secs headway (IIRC) so you will only get 33 tph if your dwell times are kept low enough. |
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Post by tubeprune on Jun 8, 2007 20:58:38 GMT
There is a document on the web for New York 1950's. Where? |
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Post by Deleted on Jun 9, 2007 1:26:03 GMT
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Post by Deleted on Jun 9, 2007 1:39:55 GMT
Does anyone know what the capacity of each line is for TPH to actual capacity by the signalling system there does not appear to be any documentation. The setup on each line is different. If you take the Victoria Line as an example, since it is well documented, the original signalling was designed on an 82 sec full speed headway - this means trains running at normal line speed without station stops. With station stop of 30 secs, the headway becomes 112 secs. A 10% margin gives the operating headway of 120 secs. Average dwell times have crept up over the years and now all they can manage is 126.5 secs = 28.5 tph. The other limiting factor is the termini. Brixton is limited to 109 secs headway (IIRC) so you will only get 33 tph if your dwell times are kept low enough. Interesting figures, thanks for sharing them with us. I have observed a RORIT on the Victoria Line at 60secs (I think it was either Green Park of Oxford Circus SB), but the train behind was not entering the station at full speed. Thus a higher frequency is probably possible, but with the effect of much slower journey times and increased stock requirements! I'm interested in how the figure of 109sec was derived for Brixton. It takes approx 96 secs for a train to depart from a platform, and a train waiting at the home signal to arrive (and the crossover to clear for the next departure). The 109sec figure would allow for 13 secs for door closing after a green signal is given. In reality, few termini of this design have ever operated with less than 30secs allowed for door closing and operating margin. An example being Times Square on NYC's 7 line, where the door closing signal could be given prior to a green signal. Whilst on this subject, the Central Line has pretty consistent minimum RORITs of 60secs, which I have observed with trains entering at both reduced speed and at full speed. This gives 60secs of dwell time and operating margin, which makes me think that signal capacity isn't the lines limiting factor! |
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Post by tubeprune on Jun 9, 2007 21:00:07 GMT
109s for Brixton is with a full speed run in.
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Post by Deleted on Jun 9, 2007 21:47:07 GMT
Does anyone know what the capacity of each line is for TPH to actual capacity by the signalling system there does not appear to be any documentation. There is a document on the web for New York 1950's. It should be noted that the NYC 1955 map shows maximum capacity, not signalling capacity. Signalling capacity is generally the time taken for a train to leave a platform, and the next train to arrive, also known as the roll out roll in time (RORIT), dynamic headway, or close in time. The map doesn't state how much dwell time or operating margin has been allowed for the figures given, some figures up to 40tph are unrealistic! Still, the actual frequencies run are reasonably impressive at around 28-32tph for many core lines, and 36tph on the 7 line. These lines had similar signalling to LU's speed control multiple home signalling. 109s for Brixton is with a full speed run in. Thanks. I don't think full speed run ins occur too often these days, certainly not during the peaks. I'm sure the new signalling and higher performance trains will shave quite a bit of time off the crossover capacity (maybe circa 10secs). |
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Post by tubeprune on Jun 10, 2007 6:36:55 GMT
The 109s Brixton headway is the new figure after signalling renewal. But the PPP definition is not the same as a normal one. It includes wheel stop to door opening time.
Regardless of that, the planned 33 tph will be dependent on dwell times and terminal capacity.
In New York, the No 7 Line has lower speeds over the 36tph section between Queensborough Plaza and Times Sq so the blocks are short, allowing more trains. The dwell times on these stations are also generally short as the traffic is low. They also have 3 tracks east of Queensborough Plaza.
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Post by Deleted on Jun 10, 2007 7:10:51 GMT
The 109s Brixton headway is the new figure after signalling renewal. But the PPP definition is not the same as a normal one. It includes wheel stop to door opening time. Do you happen to know the figures for a train that is waiting at the home signal as opposed to approaching at full speed? |
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Post by programmes1 on Jul 28, 2007 17:15:52 GMT
Right well I've worked out the capacity for the Northern line had some help here goes. This is how many trains the signals can handle now need a timetable to put in TPH current and past ones would be helpful I think I read somewhere the Northern had 110 trains 1970s?
High Barnet-Camden Town
NB 34
SB 27
Edgeware-Camden Town
NB 35
SB 31
Camden Town-Kennington (via CX)
NB 23
SB 24
Camden Town-Kennington (via City)
NB 26
SB 25
Kennington-Morden
NB 32
SB 36
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Post by superteacher on Sept 18, 2007 21:26:21 GMT
Central line current maximum timetabled frequency is indeed 30tph. The signalling could probably cope with 35tph. 33tph was often quoted as being the ultimate aim, but whether this will ever happen, who knows?
Reading Rails Through the Clay, reference is made to a theoretical 44tph service on the Hampstead tube! Douby they ever achieved it in practice. Am sure that the Bakerloo had 35tph in the days when it had 2 branches. Too many signalling simplifications have lowered many of the theoretical frequencies, and this was compounded by the removal of many platform staff in the years of declining traffic, thus increasing dwell time. They're getting their act together in respect of extra plafform staff, and with the provision of new signalling coupled with ATO, this should mean a return to frequencies acheived in years gone by.
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