Service Frequency

[Andyh82]

The majority of Underground lines or combinations of lines in Central London seem to have an off peak service frequency of 24 trains per hour which gives a train every 2.5 minutes (Victoria Line is more than this, and I’m excluding the W&C)

But the Bakerloo Line only has 19 trains per hour, both Northern Line branches 20 trains per hour and the Piccadilly Line is 21 trains per hour.

Is the reason for this lower frequency a lack of rolling stock, signalling or operational limitations or perceived lower usage on those lines compared to the rest?

 

[si404]

Is the reason for this lower frequency a lack of rolling stock, signalling or operational limitations or perceived lower usage on those lines compared to the rest?

First two for all three, additionally demand for the Bakerloo.

 

[NSE]

With regard to the Piccadilly and Northern, they both have branches so service frequencies will have to work with them. For example 30 trains per hour through each Northern branch would be great, but that means Morden and the Kennington loop will need to handle 60 tph. Nor could the signalling I should think! With regards to the Bakerloo, it’s not the busiest line. I’d wager that all lines are running virtually up to a limit in some way shape or form. Whether it’s stock limit, signal capacity or no more drivers etc.

 

[Mikey C]

The Northern Line signalling would surely be able to cope with a higher frequency, it's the restrictions at Camden Town I assume which reduce the frequency

 

[TheDavibob]

I believe the plan for the Bank closure will lead to 30tph from Camden Town to Morden, so clearly there is the capacity to run such a service (south of Camden Town) if stock/demand called for it, with the caveat that this would only be (30+16)tph through Camden Town.

Wikipedia quotes a potential for 36tph with full segregation (i.e. splitting at Camden Town) this gets into a snarl of insufficient stock. There's a(n out-of-date) London Reconnections on Northern line capacity.

 

[Tetchytyke]

For example 30 trains per hour through each Northern branch would be great, but that means Morden and the Kennington loop will need to handle 60 tph. Nor could the signalling I should think!

30tph on each branch just means 30tph at the end of each of the branches?

The issue on the Northern is Camden Town. You see this in the AM peak; northbound trains are segregated and so AIUI there are more northbound trains than southbound ones, which are not segregated.

Segregation would increase capacity, except Camden Town couldn't cope with the level of Interchanges needed to make it work.

 

[Lewlew]

A big issue on the Bakerloo is the amount of trains reversing at Queen's Park, to up the frequency in the tunnel then more trains would need to run north of Queen's Park but then you would also need more trains and for somewhere for them to go.

 

[NSE]

30tph on each branch just means 30tph at the end of each of the branches?

The issue on the Northern is Camden Town. You see this in the AM peak; northbound trains are segregated and so AIUI there are more northbound trains than southbound ones, which are not segregated.

Segregation would increase capacity, except Camden Town couldn't cope with the level of Interchanges needed to make it work.

My point was more having Charing Cross and Bank capable of 30tph is fine, but it has to take into account that that would be 60 from Kennington southwards. Or whatever the split between Morden and the Kennington Loop is. Essentially, trying to say that just because it can be handled through one section of the line doesn't mean it can on every section! I knew what I meant haha

 

[Tetchytyke]

My point was more having Charing Cross and Bank capable of 30tph is fine, but it has to take into account that that would be 60 from Kennington southwards. Or whatever the split between Morden and the Kennington Loop is.

Apart from at peaks, everything from Charing Cross just goes round the loop and back where it came from. And during peaks you do get 30tph Kennington-Morden (and heaven knows it needs it south of Stockwell).

You're right that the two branches both north and south of Camden Town complicates things, which is why the morning peak service is better than the evening peak. In the morning there's a definite contra-peak north of Euston so the service can be segregated at Camden Town, but in the evening it can't be.

 

[Domh245]

My point was more having Charing Cross and Bank capable of 30tph is fine, but it has to take into account that that would be 60 from Kennington southwards. Or whatever the split between Morden and the Kennington Loop is. Essentially, trying to say that just because it can be handled through one section of the line doesn't mean it can on every section! I knew what I meant haha

As it stands at the moment (and for the forseeable), apart from a few workings in the peak everything on the bank branch runs through to Morden, everything on the Charing + branch runs round the loop (and in the near future to Battersea) - both of which should be capable of sustaining 30tph

 

[LU_timetabler]

As it stands at the moment (and for the forseeable), apart from a few workings in the peak everything on the bank branch runs through to Morden, everything on the Charing + branch runs round the loop (and in the near future to Battersea) - both of which should be capable of sustaining 30tph

And then you need extra rolling stock. There's always a limiting factor. Either signalling or rolling stock. Current plans for Battersea opening will not send all Charing + trains to Battersea, some will complete the loop at Kennington.

 

[Trevor Yerlett]

Another consideration when increasing the service frequency is capacity of the power supply system - it could become overloaded.

 

[philthetube]

I don't think this is an issue on the Underground, is cases of disruption the system seems to be able to cope with as many trains as arrive into a given area.

It used to be an issue travelling north from Baker St. on the Met, controllers have occasionally been heard to start trains moving one at a time in order to prevent the power tripping out

 

[Trevor Yerlett]

Short term disruption may be ok, but it is an issue if there is a change in the working timetable to higher frequency and/or higher speeds - I speak as a rail professional who has been involved in computer modelling of such scenarios.

 

[Mojo]

I don't think this is an issue on the Underground, is cases of disruption the system seems to be able to cope with as many trains as arrive into a given area.

It used to be an issue travelling north from Baker St. on the Met, controllers have occasionally been heard to start trains moving one at a time in order to prevent the power tripping out

It’s quite often the case that too many trains in the section can momentarily cause traction current blips.

It’s also occasionally the case that equipment within substations is temporarily limited or switched off for maintenance or repairs, which can be another limiting factor.