SSR Resignalling

32tph is the planned frequency once 4LM is completed in 2022.

I took your initial reply to be in the context of the current timetable.

Having looked at several sample periods in the current District line timetable, eastbound and westbound in both peaks, I keep getting 27 scheduled trains per hour (including terminators & Circles).

Should 4LM ever be completed........there is an element that insists it will never happen on Network Rail metals or indeed beyond the scope of SMA8 even though the cable management systems and new equipment rooms have been built........I'm still wondering where those extra five trains per hour will terminate either side of zone 1 as its already been said elsewhere on the forum recently that increasing conflicting moves in the wrong places can actually have a negative impact and strangle capacity.

Don't forget the current Tower Hill reversers are supposed to be extended to Barking in the new world so the only reversers at Tower Hill would be ad-hoc for service disruption / recovery purposes. Barking is already a bottle neck at times and even with CBTC, I can't see it handling much more than it already does - so the already planned extended Towers will pile the pressure on let alone adding another five trains per hour on top.

And looking to the west end of the line, there won't be any capicity increase on the Richmond or Wimbledon branches as the Network Rail signalling system isn't being replaced........and we're supposed to losing the Ealing branch (to the Piccadilly line). So before anyone tries to fit in another five trains at the west end, where are the current Ealing trains going?! Rayners Lane perhaps? Fair enough if that's the case - indeed the five extra trains per hour would pretty much maintain the current frequency.........but does the S7 fleet number enough trains to essentially facilitate an extension of the line?

Thing is, the SSR isn't like a deep tube line. We might well be getting a deep tube style signalling system but I just can't see it delivering the same type of service.

When the Olympia service ran all week long during the peak it struggled and was usually fitted in through the gaps.

Even though when everything was running to timetable it was extremely tight at Earls Court and at West Kensington East Junction

Yes, that’s exactly how the theory should work. The computer knows where each train is, and therefore the time it will reach the junction, and can manage dwell times and such like accordingly.

The experience with Edgware Road and Baker Street does not necessarily back that theory up...

Manually routing the trains across via the computer would be a very time consuming process.

The Jubilee does it - I think its Willesden Green where this is done, and it can delay the next few trains. 

That area is not in scope for CBTC and would thus need adding to the project. Although a small addition in the grand scheme of things, the extra costs etc would likely kill that suggestion before it could gain any traction.


CBTC - if it gets fitted - is not replacing the current Network Rail signalling system on the Wimbledon & Richmond branches. CBTC will be overlaid in these areas.


Dagenham East maybe, but if everything going east gets pushed beyond Tower Hill, Plaistow will have too many trains per hour passing through it.

Granted trains will cause a minimal delay when terminating, but by nature of the bay road being to one side of the running lines, departing trains delay both eastbound and westbound roads which would be self defeating.

Centre bay roads are far superior as they only cause a delay in one direction.

PICU only replaced the non safety signalling i.e the actual control circuits of the areas concerned. It has nothing to do with the safety signalling, that is still controlled locally from IMR’s. It just basically moved the affected areas out of Earls Court control room to the new control room at South Kensington. As far as the signalling on site is concerned its still connected to Earls Court

Manning IMR’s is not an option signallers are not trained to operate a local frame in a IMR. In the normal environment PG is quite quiet with just through running but when the service goes up the wall its very complex with the stabling. Remember in the control room they push a button for a route the signalling does the rest, moving the correct lever or levers. Another thing to note PG has 2 IMR’s East & West the signalling east of the station is easier but the west side of the station is complex. I don’t see this as an option realistically and don’t forget Putney Bridge yes the points have gone but the signalling is still controlled from a IMR its not automated

Well its an “ operating official “ who tells the Technical Officer what route is required from the signaller, this on the District is usually a DRM but from past experiences this is not the case and the Technical Officer does 98% of the work.

Once upon a time and I forgot to include this in my original post but Earls Court control room was in the stage of Asbestos removal and there was concerns it would of needed to be shut for a couple of weeks 24/7. As such signal ops as they were called did get training on operating a V and N style frame. They even got special stools installed in the IMR’s and a folder was produced for each site detailing how it worked manually, but it never happened and the asbestos removal was carried out in Engineering Hours only.

Interlocking Machine Room - Remotely operated control interfaces that are only staffed in emergencies/failures, lines under Automatic Train Operation tend to reclassify these as Signalling Equipment Rooms

Piccadilly Interim Control Upgrade - A fixed block signalling patch that ducks wholesale re-signalling for at least another 15 years

Duty Reliability Manager - part of Service Control staff reporting to a Service Manager

V and N Style Interlocking Frames - Types of control interfaces built by Westinghouse found in Interlocking Machine Rooms

DWS, is this a statement of fact, or are you being sarcastic? Not knowing the manpower locations and staffing levels, I'm pleading ignorance.

Thank you for that

Standard staffing for signal cabins, although I agree that DWS could have phrased it a little better.

Earl’s Court needs four staff per day to work a single shift (early, middle, late, night) - three if you made it a 12-hour job.

Staffing both IMRs instantly doubles that requirement, and introduces additional complexities involving staff welfare facilities. Whilst they’re not insurmountable, it would ultimately be easier to just retain the status quo.

Incidentally, Parsons Green is one of the only V-style frames to be routinely staffed historically; they were designed purely for remote working.

You forgot the meal reliefs 😂

Thanks for that