TBTC Testing

You mean until the first motor falls off after which it'll be turned down again?

Will the Central Line ever go back to the original line speeds that the CLP was supposed to deliver?

Returning to topic I hope there is eventually some gain for all the pain.

I am informed by a very reliable source that one of the reasons for the variable speeds on the Jubilee is that the control system tries to adjust train speeds to the present timetable. So, if a train is running late, or there is a gap ahead of it, it goes full speed. If it's running to time or getting to be early, the system slows it down a bit to match. Once the whole line is turned over to ATO and de-bugged, there will be a new WTT with better runing times.

Actually, part of the increase in the number of trains per hour (tph) is, in the case of the Jubilee Line, because the new TBTC allows the removal of full speed fixed overlaps. Instead, overlaps match train speed (more or less). Hence, with overlaps matching speeds, trains can run closer together, particularly at lower speeds. Thus, you can get a more frequent service for the existing line speeds.

The other factor is ATO. If you take the judgment for driving and braking away from the driver, you can usually get a faster run in to stations and up to signals because the ATO element will take the braking rate up to the maximum possible. This alone will account for almost half the 6 more trains per hour on the new Jubilee service.

Experience will show what can be done, once the new system has settled down but the things which have to be skillfully managed are the station stop times, which must not go over 40s, crew changeovers and the tip out times for short workings like Willesden Green. This is where the 30 tph could be lost.

There are pros and cons to this style of driving though - high acceleration and maximum braking leads to more wear and tear, and power consumption, and leaves less margin for error if something goes wrong - poor adhesion, object or person seen on the track, that a human operator may be able to allow for.



This seems to be a misplaced priority: the object of the exercise is to move the maximum number of people (NOT trains) from A to B. Dwell times need to be long enough to allow anyone who can board to do so. I've been at stations where an attempt has been made to close the doors even whilst people were still getting off - let alone anyone having a chance to get on!
If dwell times are a Bad Thing, why stop at all? - you could get far more trains through the system that way!

I took a jolly on the Jubilee today from Finchley Road. Unfortunately the on-off nature of the speed control had the effect of gently rocking me to sleep and I ended up at Canning Town :S

You are right, but it depends on your priorities. LU's main one now is to manage the overcrowding. That means using the system to its maximum capability. If you buy an expensive piece of kit like a train (£6m each), you have to sweat the asset. It's built to take it. If you buy even more expensive signalling kit, you must sweat that too!

Variations for adhesion are taken into account. That's one of the reasons why the signalling is designed for trains to run at <95s headways but the timetable allows 120s headways. As for allowing for objects or persons on the track, any of the drivers on this forum will tell you that stopping before hitting anything which shouldn't be there is almost always impossible, regardless of the speed you are going.



Now, now! ;D ;D You have to remember that when a train is crowded, the rate of loading and unloading slows down and the dwell time lengthens. If the train stands at the platform too long, the following train will "catch up" and stop outside the station. When the train in front eventually leaves, the waiting train has to restart, accelerate run in and brake to a stop. This wastes more valuable seconds so that the third train will now get a slow down command etc. etc. A few seconds makes a huge difference.

If trains are allowed to wait too long at stations, the whole line suffers and passengers will have to wait longer and will travel more slowly. That's why I make such a fuss about dwell times.

Or, think of it this way: The Jubilee has 29 stations. If you waste 2 seconds at each station, you will have lost almost a minute by the end of the trip. If every train arrives a minute late at the terminus, you would quickly end up with a 20 tph service.

Stupid question, is the touch of brake necessary? In the sense that instead of a maximum speed could not a maximum speed range be developed, say -1%+3% or something? The maximum speeds on conventional lines above 5mph increase so it seems in 5mph increments, can that resolution be increased with ATO/TBTC? Or is it already done like that? Sure I read somewhere that something similar to having a range is implimented anyway in terms of repowering speed being slightly below that of maximum speed.

Finally the outright untruths about the management statistics for Jubilee Line "reliability" are starting to get noticed and revealed in the media.

www.bbc.co.uk/news/uk-england-london-12518589



It's not just weekends, of course. Look at all the days after Christmas when there was no Jubilee service. Doubtless those weren't counted as well.

For the information of the Jubilee Line management, the "schedule" is actually posted up on every platform. This shows that trains start early in the morning 7 days a week, run the full length of the route from Stratford to Stanmore at all times, and finish late evening. This is the definition of "scheduled services" you will find from the dictionary.

Auntie Diana has noticed on several occasions three adjacent posters on the platform at Canning Town. The first shows this generous schedule, the second gives details of yet more continuing closures and shutdowns on weekends way into the future, and the final self-congratulatory one says how nearly 100% of trains are being run .......

Being that the Jubilee line's stock (1996) has effectively stepless control, you would have thought that TBTC could use this to set the speed, as there is going to be a position somewhere that holds the speed steady.

A skilled human driver could do this. I think TBTC can do things similar but it's nowhere near as crude as the go/anchors method used on the Central..

This YouTube clip demonstrates the announcements being played twice:

The original plays 3 quarters of the way through the tunnel, whilst the new TBTC triggered one plays just as the train is pulling into the stations (similar to the 1995/2009/S stocks)

Nothing can beat the skilled input of a human, simple as!

I'd say part of the reason the 67 ATO is so smooth is the crudeness of the traction systems taking so long to respond. You do make a fair point about rail gaps, as they are of varying length for say pointwork, or some for isolation gaps. Nothing other than a busline would solve the jerkiness from that, and two problems there; a) not permitted b) unsafe.

Give a driver a DTG display and a time either side of timetable and problem solved.

This is nothing new, on most lines the T/Op can judge how close the train in front is due to the numbers of people on the platform, and the dot-matrix gives an indication of the gap behind.

As I've said before, a decent Train Operator can do everything ATO can do.

If its dead its too late for the doctor, the undertaker more like it!