Slow stretch on the Metropolitan line

[Metrider]

As my name suggests, I'm usually riding into town on the Metropolitan line, which is usually a very good service. However, I was wondering why it seems to take so long to get between Finchley Road and Baker Street? This is timetabled as 7 minutes (even for "Aldgate (fast)" trains), even though there are no stops between Finchley Road and Baker Street.

For comparison, the Jubilee Line also takes 7 minutes to get between Finchley Road and Baker Street, with two stops on the way (Swiss Cottage and St John's Wood)!

Does anyone know the explanation for this? Is there any chance of an improvement in the future (e.g. when the 4LM is complete)?

There's probably nothing to be done about it, but it's just a bit vexing for my journey to take 20 minutes to Finchley Road (which covers a large distance of around ten miles!), then another 7 minutes just to go that final short stretch into Zone 1.

 

[Dstock7080]

Track geography is the main limitation for the MET, passing through 3 closed stations.
Off peak scheduled 5¾min for both between Finchley Road and Baker Street.
Both are CBTC/TBTC.

 

[A60stock]

So this is my take on things since the area was re signalled (happy to be corrected by the experts):

The southbound journey between Finchley and Baker St is quicker, and generally runs to full line speed. The Northbound is slower than under pre CBTC. I don't get why this has not been addressed as the area has been under CBTC for close to 6.5 years now.

More recently, the run between Finchley and Wembley was converted to CBTC. I believe the Northbound run is close to running at full line speed in all areas but could be improved in a few sections.
However, the southbound journey, originally, trains were pelting at full speed the full way post CBTC until recently, when the run was changed to quite a leisurely pace between Wembley and close to Kilburn. I believe the reason was due to an issue with the track at Willesden Green. Why the trains cannot run quicker (as they were before), until just before Willesden Green is something I do not get and I am not sure why they have been slowed for almost the entire leg, only going to full speed around Kilburn.

I am hoping speeds are improved as the full benefits of CBTC running at full line speed can be realised, like is done on the Jubilee , where trains are running to their full benefit and speed the entire way. CBTC on the Met Main (asides from Finchley to Baker St) is in its infancy so I am hopeful there is much more to come performance wise.

 

[Metrider]

So this is my take on things since the area was re signalled (happy to be corrected by the experts):

The southbound journey between Finchley and Baker St is quicker, and generally runs to full line speed. The Northbound is slower than under pre CBTC. I don't get why this has not been addressed as the area has been under CBTC for close to 6.5 years now.

More recently, the run between Finchley and Wembley was converted to CBTC. I believe the Northbound run is close to running at full line speed in all areas but could be improved in a few sections.
However, the southbound journey, originally, trains were pelting at full speed the full way post CBTC until recently, when the run was changed to quite a leisurely pace between Wembley and close to Kilburn. I believe the reason was due to an issue with the track at Willesden Green. Why the trains cannot run quicker (as they were before), until just before Willesden Green is something I do not get and I am not sure why they have been slowed for almost the entire leg, only going to full speed around Kilburn.

I am hoping speeds are improved as the full benefits of CBTC running at full line speed can be realised, like is done on the Jubilee , where trains are running to their full benefit and speed the entire way. CBTC on the Met Main (asides from Finchley to Baker St) is in its infancy so I am hopeful there is much more to come performance wise.

Thanks for the info! I couldn't find much information on 4LM actually reducing journey times (it seems more focussed on allowing more trains to run closer together?), but it would be a nice bonus of course.

 

[BanburyBlue]

What is CBTC and TBTC?

And what are the closed stations?

Thanks.

 

[150219]

What is CBTC and TBTC?

And what are the closed stations?

Thanks.

Communication/Transmission based train control.

From Finchley Road, they are Swiss Cottage, Marlborough Road and Lords.

 

[BanburyBlue]

Communication/Transmission based train control.

For the uninitiate, what does this mean (in simple terms), and why does it affect train spee?

 

[Pegpilot]

Hi Banbury. In simple terms CBTC/TBTC is a computer based train control system. The train knows its position by various means, like fixed lineside position beacons, wheel rotation counters, counting signal cable loop crossovers in the track, and send this back to a central computer that therefore knows the positions of all trains on the line. The system then sends back a Limit of Authority signal to the train (i.e. how far the train is allowed to advance until it needs to stop) and the train works out its speed profile and will automatically brake to that point. The train's own computer also has a line speed profile uploaded (i.e. speed limit at every point on the line) and if the train tries to exceed that speed then the brakes are applied. Huge over-simplification but that's the bare bones. On LUL the following lines have some form of CBTC/TBTC

Central - a bit of an antiquated system dating back to the 1990s
Jubilee - Very similar system to DLR, same supplier, installed in the noughties
Northern - ditto
Sub Surface - currently being installed
Victoria - Now on its second generation ATO system fitted in the noughties

The means of communication to/from the train varies. On the Jubilee it's done through a radiating cable system in the track. The cable loop crosses over every 20 metres or so, and the train count these loop reversals to work out where it is. Other systems use radio based transmission. Clearly radio can be a bit tricky underground but the disadvantage of the track loop system is that you need to be very careful not to damage the cable when you do track maintenance. Of course these systems are designed to facilitate automatic driving, but trains can be manually driven in PM (Protected manual) with the CBTC system ensuring that speed profiles and LOA's are not exceeded and overruling the driver. It's been a few years since I was involved with all this and I'm sure those with more recent knowledge will correct me if I've made any mistakes. Oh, and when I got involved in the initial testing of trains on the Jubilee in ATO the accuracy of the trains' speed control was simply stunning - we were replicating the same speed/distance curve with every test.

Hope that helps

A retired train performance wonk

 

[BanburyBlue]

Hi Banbury. In simple terms CBTC/TBTC is a computer based train control system. The train knows its position by various means, like fixed lineside position beacons, wheel rotation counters, counting signal cable loop crossovers in the track, and send this back to a central computer that therefore knows the positions of all trains on the line. The system then sends back a Limit of Authority signal to the train (i.e. how far the train is allowed to advance until it needs to stop) and the train works out its speed profile and will automatically brake to that point. The train's own computer also has a line speed profile uploaded (i.e. speed limit at every point on the line) and if the train tries to exceed that speed then the brakes are applied. Huge over-simplification but that's the bare bones. On LUL the following lines have some form of CBTC/TBTC

Central - a bit of an antiquated system dating back to the 1990s
Jubilee - Very similar system to DLR, same supplier, installed in the noughties
Northern - ditto
Sub Surface - currently being installed
Victoria - Now on its second generation ATO system fitted in the noughties

The means of communication to/from the train varies. On the Jubilee it's done through a radiating cable system in the track. The cable loop crosses over every 20 metres or so, and the train count these loop reversals to work out where it is. Other systems use radio based transmission. Clearly radio can be a bit tricky underground but the disadvantage of the track loop system is that you need to be very careful not to damage the cable when you do track maintenance. Of course these systems are designed to facilitate automatic driving, but trains can be manually driven in PM (Protected manual) with the CBTC system ensuring that speed profiles and LOA's are not exceeded and overruling the driver. It's been a few years since I was involved with all this and I'm sure those with more recent knowledge will correct me if I've made any mistakes. Oh, and when I got involved in the initial testing of trains on the Jubilee in ATO the accuracy of the trains' speed control was simply stunning - we were replicating the same speed/distance curve with every test.

Hope that helps

A retired train performance wonk

Thanks - that’s very informative- appreciated