SSR Resignalling

Going back to the Met line area, SM8/9, once these are done, I am hoping that the max speed trains currently achieve on the fast routes, routinely around 62-65mph (especially northbound between Finchley road and Wembley Park and Southbound fast Moor Park - Harrow - Finchley) are not slowed down. I am taking example from from the route between Finchley and Baker street which now seems slower overall than pre
re-signalling.

Does the reason above also have anything to do with why trains do not run as fast as they could between Finchley and Baker St (particularly on departing Finchley Road)

CBTC can afford to be more generous with limits since they are verified and enforced by the system. That is not generally the case with conventional signalling, although a speed-controlled trainstop will do that.

I did think it might be something to do with that, however, no matter when you travel, be it off peak, rush hour, late night etc, the departure leaving Finchley is very slow until a little while after the Swiss Cottage crossover. I am sure that pre CBTC, this was not the case. The same applies to just after you depart baker street going northbound, where it seems much slower then it was pre CBTC.

I compared two videos of a northbound journey, baker street to Finchley road (drivers eye view), one being a current video depicting an s8 stock doing the journey in 2023 and the other being an A Stock doing the same journey in 1992 (great watch btw). I put these two videos next to each other to see which one got to Finchley first. Now, unless the video in 1992 skipped part of the journey, the A stock got there a minute or so before the s8 stock did. I cannot understand why this is slower****. It has been 4.5 years since cbtc came in.

By contrast, the jubilee line looks like an ideal example of running automated signalling to its peak, where the trains are generally quicker almost everywhere then pre automation.

****I agree that in all other areas where CBTC is on the met, it seems to be quicker than under conventional signalling and I am generally happy it replacing the old and outdated signalling. However, I just hope we dont see trains being slower in other areas, especially on faster sections.

DStock’s post does back this up - there is a lower speed on leaving Finchley Road station (12mph) and then 19mph on Swiss Cottage Crossover (I presume this is the normal route and not when the crossover is being used?)

Incidentally Colin mentioned a similar thing up-thread where CBTC is slower over Embankment crossover than manual driving


Could the Finchley Road case be a temporary speed restriction related to track?

Update: I’ve tracked down a quote from goldenarrow which seems to explain this Finchley Road southbound situation:

Perhaps I can comment as a recently retired District Train Operator, who commenced my career working CO/CP and R Stock, the CBTC system has its foibles and is generally very good doing what it is designed for in normal operation.

PM Protected Manual is quite difficult get on with, as you (in my opinion) constantly looking down at the SID Signal Interface Display which is the only reference for the state of the road ahead. There are audible prompts for potential overspeed violations etc. and changes in status which can be quite distracting. All changes in maximum speed are mandated by the system and the driver has to react to these promptly to avoid an emergency brake, especially when the limits are reduced.
Entering a platform under conventional signals the driver is just trying to align the cab with the stopping markers at the far end of the platform. Under PM driving the system is continually warning about potential over-speeding when entering a platform and reducing the maximum permitted speed every few seconds. This can be disconcerting while the driver is looking down and then up to see the progress into the platform.

Until the recent publication of mandatory PM driving at certain locations and at certain times on SSR it has been the individual driver choice as to whether conduct the train in ATO or manual, many of my former colleagues preferred not to use PM driving as it was perceived as being too much faff to bother with!

Perhaps, making it ‘awkward’ to operate was the aim, therefore keeping most trains within the system.

Not quite that simple:

As Dstock7080 says, driving in PM is quite disconcerting.

Because it's a moving block style system you never quite know what it's going to do next. It'll drop the speed limit on you and expect an instant response - if it doesn't get one it'll throw overspeed imminent warnings, then before you know it the emergency brakes have been applied.

I find as an experienced driver, it's doubly hard to drive in PM because I knew where I could coast or motor, what the line speeds were in any given area and how far it was to the next signal (therefore how far I was clear to drive my train). With CBTC I only know what the in cab signalling is telling me......and again with the moving block nature sometimes the target speed and distance to go are constantly changing quicker than my brain can compute the information. I hate PM driving and I can confidently state the vast majority of my colleagues hate it too.

However, with my instructor's hat on, I find trainee's get on with PM driving quite well. Because they don't know the line they find it easier to go with what the system is telling them as they don't know any different.

We are now targeting SMA8 (Finchley Road and Preston Road ) to go live in early 2025 and the final section of signalling, SMA14 (Rayners Lane to Uxbridge) to go live in 2026. Commissioning of the signalling on all our Engineering Vehicles is planned to be completed alongside the go live of the final signal migration area.

But, "further optimisation of the commissioned signalling software is required in certain areas". Achievement of a reliable 32 trains per hour service level is also dependent on the renewal and remodelling of Aldgate Junction, currently targeted for summer 2027.

The Heavy Maintenance Facility upgrade works at Neasden Depot remaining packages for the Heavy Lifting Shed and the new Staff Accommodation building, once complete in 2025 will enable the planned overhaul of the new trains.

(TfL Programmes and Investment Committee meeting 26 June 2024)

Re Aldgate Junction remodelling what is the plan for this.

sorry for being somewhat cynical but possibly this means 'reducing flexibility'

Several 'End-State Track layout' changes got dropped, but I don't recall Edgware Road being somewhere planned for more changes. The two sidings were reduced to one, long enough for an S7 train instead of a 6 car C stock as part of the S stock enabling work quite a few years ago now.

There was talk of a P&C renewal at Edgware Road for 2020/21 but it never took place, and from memory the scope was renewal (with electric point machines replacing air) rather than remodelling. I remember being asked to look at the Testing and Commissioning requirements not long after joining 4LM.


Yes and no. The two single slips are planned to be removed, which removes the possibility of reversing a Met or Circle train in Aldgate OR platform, but in practice it's not possible to berth an S8 in there and get all doors open (they have to draw forward into the trap road) and it doesn't get used a lot even for an S7. This has been compensated for by the provision of additional reversing capacity at Tower Hill (using the middle platform).

There are plans to add an extra crossover to permit parallel met arrivals/departures which compensates for the removal of the other single slip. It should be noted that slips are bespoke and generally disliked from a reliability perspective and this should aid reliability with a slight trade off with the loss of one seldom-used reversing move.

I am surprised that this is not already possible. Even though it very much depends on which platforms the two trains are using it does sound like a welcome added benefit.