Can drivers drive in TBTC

On the Jubilee Line it is frowned upon, however the Northern Line seems so far to have taken a softer line.

In reality most drivers prefer to leave the train in ATO because driving in PM is frankly a hurrendous experience. "Overspeed immiment" warnings coming up when you're 5 mph under the target speed and coasting on a 1 in 50 uphill gradient for example, or imposing a ridiculously slow approach to platforms.

What amuses me is when passing from the manual section to the TBTC migration point, the difference in driving technique is enourmous! In manual mode the trains accelerate down the hill from Belsize Park and the drivers tend to just apply a light brake to keep the speed constant if necessary, then full brake into the platform, stopping with a brake release for smothness. *Switch over to TBTC in Chalk Farm platform* until Euston its power on, brakes on, power on brakes on... its rather crude to say the least, the ATO also seems to bring the trains to a hault with a noticeable jolt, whereas drivers stop a lot more prodessionally giving you a smooth ride. I swear at one point I felt motion sickness setting in, after a bevvy or two anyway.

Humans 1, computer 0, huraaah!

TBTC is the system type of ATO that is all.

LT/LU so far has had 4 line wide ATO systems

Old type Victoria line ATO before VLU,
Central Line ATO,
VKU Victoria line ATO (DTG),
Jubilee/Northern lines ATO (TBTC)


TBTC can also be called CBTC; the brand name of J/N TBTC is Seltrac S40 (from Thales).

Some will insist TBTC and CBTC are different things, but usually those difference are down to the detail of how a particular maker implements some of the details thats all.


It could be argued in some respects Central Line ATO is a CBTC/TBTC system - on the Central your train code frequencies are superimposed on jointless track circuit frequencies, but on J/N they are in a seperate carrier cable loops in the four foot and there are no track circuits. But at low level their ain't a lot of difference once you see through all the makers jargon. Both involve carrier frequencies with superimposed commands.

SSL will be yet different again ATO but is also generically a CBTC/TBTC - Bombardier Cityflo 650.


The other thing to these systems are the other elements. ATC is made up of up to 4 elements ATO ATP ATR ATS.

ATO is only one element, but TBTC is a system with all 4.







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Nick

I would have said that the DTG-R system drives the train harder, despite coasting.

On the Northern Line between KX and Angel s/b, the speed profile is currently as follows - this is from memory so the details might not be quite spot on. Up to 20 mph. Then up to 35 mph. Down to 20 mph. Up to 35 mph. Down to 28 mph. Up to 35 mph. Down to 28 mph. Stop at Angel platform. When TBTC was commissioned, overnight section this went from a section which was plain 35 mph and through which trains routinely used to run at 30 to 35 mph. Noone seems to be able to give a consistent answer as to why the change. Other sections give similar crazy speed profiles. Measurements show the TBTC is actually achieving worse run times in some sections than under previous manual driving.

There is currently a massive difference in driving profile between the Northern and Victoria lines - on the Vic line generally the train goes straight up to line speed and then at some point coasts (which appears to vary depending on whether the train is running late). The Northern Line's driving profile is simply all over the place. Motoring up hill, then the VOBC thinks 'I'm going too fast so I need to brake now even though I'm on a 1 in 50 uphill gradient', 'Oops I've overbraked now so I need to motor'. Driving in PM allows the Train Operator to smooth out some of this without losing time, but the cost is the unfortunate Train Operator has to listen to constant beeping noises in the cab telling him the train is about to overspeed when it most certainly isn't!

Granted TBTC is in its infancy on the Northern Line, however the way I see it the DTG-R system has delivered a genuine improvement on the Victoria Line in terms of speed and reliability, the Jubilee Line is hard to compare because the old signalling on that line provided a very low TPH anyway, but on the Northern Line at the moment all I see is money spend to deliver a slow and poor ride. If a Train Operator drove as badly as the Northern Line ATO currently does, they would fail a driving assessment.

i'll second that, first time on the northern line since i moved to the district line a year ago. that ride was the first time i've suffered from motion sickness in over 20 years, the TBTC upgrade provides a terrible ride

Double post removed by Londonstuff