Partly-electrified network: what would you do for stock?

[nw1]

A bit of a hypothetical discussion:

Let's say there was a network of lines, both outer-suburban and medium-distance, spreading out from a large city.

Let's say it was considered economically viable to electrify out to around 80 miles, but not beyond there, due to lower traffic.

Let's then say there were three classes of mainline service:

1. Outer-suburban stoppers, typically fast to the city boundary, then most or all stations beyond, and within the 80 mile limit of electrification;
2. Fast and semi-fast services terminating within the 80 mile limit of electrification;
3. Fast and semi-fast services extending beyond the 80 mile limit.

There are less examples of 2) than there are of 3), so most fast and semi-fast routes involve partially non-electrified track.

Let's say it was desirable to deploy 3x2 seating, high-density units for the first, but 2x2 seating, lower-density, higher-comfort units for the second and third.

Would you suggest:
- a 3x2 EMU class for the first and
- 2x2 bimodes for the second and third;

or
- a 3x2 EMU class for the first
- a 2x2 EMU class for the second and
- 2x2 bimodes for the third.

The first has the advantage of flexibility, in the sense that there are more bimodes available for the non-electrified sections in case of unit failure, so even though the plan involves running bimodes on fully-electrified routes, there is more resilience. It also allows for interworking of the fully-electrified and partially-electrified routes where this might be more efficient.
The second perhaps has the advantage that plain EMUs are cheaper compared to bimodes.

I'd guess the best overall would be the first (3x2s and bimodes only) but interested what others' opinions are.

 

[30907]

Make it 83.75 miles and you have Salisbury to a T (the outer-suburban stoppers don't get beyond Worting Jn, but they might if it was electrified)

I wouldn't opt for 3+2 for the stoppers over that sort of distance, so you could do the job with 2 types of unit. The EMU might be higher-density seating than the Bimode, or have doors at 1/3 and 2/3 while the bimode was end doors.

 

[nw1]

Make it 83.75 miles and you have Salisbury to a T (the outer-suburban stoppers don't get beyond Worting Jn, but they might if it was electrified)

I wouldn't opt for 3+2 for the stoppers over that sort of distance, so you could do the job with 2 types of unit. The EMU might be higher-density seating than the Bimode, or have doors at 1/3 and 2/3 while the bimode was end doors.

True, though we already have the 444s running the fully-electrified lines: I was thinking of the case where a complete fleet renewal was due. Basically, how acceptable is it from a financial POV to have bi-modes operating over fully electrified track, is what I'm getting at. Is it good (because the bi-modes can do both fully-electrified and partly-electrified fast routes, improving flexibility and resilience) or not so good (because bi-modes are perhaps more expensive than straight EMUs)?

So for example, regarding Salisbury, would you also have the bimodes on the fast Salisbury terminators (e.g. Clapham, Woking, Basingstoke then all) if it was electrified that far? I'd agree that the 3x2 would make sense for "true" stoppers i.e. Basingstoke stoppers extended to Salisbury, this would be comparable to the use of VEPs on Southampton or Bournemouth '93' stoppers in the days that they existed.

 

[30907]

True, though we already have the 444s running the fully-electrified lines: I was thinking of the case where a complete fleet renewal was due. Basically, how acceptable is it from a financial POV to have bi-modes operating over fully electrified track, is what I'm getting at. Is it good (because the bi-modes can do both fully-electrified and partly-electrified fast routes, improving flexibility and resilience) or not so good (because bi-modes are perhaps more expensive than straight EMUs)?

I was also assuming starting from scratch.

So for example, regarding Salisbury, would you also have the bimodes on the fast Salisbury terminators (e.g. Clapham, Woking, Basingstoke then all) if it was electrified that far?

Probably not. I would aim to use the EMU unless it was operationally useful to interwork with the long-distance Bimodes.
(I agree you would want more than the absolute minimum number of bimodes for resilience.)

I'd agree that the 3x2 would make sense for "true" stoppers i.e. Basingstoke stoppers extended to Salisbury, this would be comparable to the use of VEPs on Southampton or Bournemouth '93' stoppers in the days that they existed.

Did you mean  argue? We don't agree!

 

[HSTEd]

The TGV-M is supposedly capable of swapping out its interior inside 12 hours.
If we assume that other modern trains can be made to do likewise, I would propose a single uniform fleet of electrodiesels for all tasks.

 

[swt_passenger]

True, though we already have the 444s running the fully-electrified lines: I was thinking of the case where a complete fleet renewal was due. Basically, how acceptable is it from a financial POV to have bi-modes operating over fully electrified track, is what I'm getting at. Is it good (because the bi-modes can do both fully-electrified and partly-electrified fast routes, improving flexibility and resilience) or not so good (because bi-modes are perhaps more expensive than straight EMUs)?

So for example, regarding Salisbury, would you also have the bimodes on the fast Salisbury terminators (e.g. Clapham, Woking, Basingstoke then all) if it was electrified that far? I'd agree that the 3x2 would make sense for "true" stoppers i.e. Basingstoke stoppers extended to Salisbury, this would be comparable to the use of VEPs on Southampton or Bournemouth '93' stoppers in the days that they existed.

If on a network like SWR‘s where they have less than 30 DMUs, but the equivalent of about 325 4 or 5 car EMUs, (counting 701/0 twice), it would be fairly ridiculous to make a full fleet replacement all bi-mode, no matter what minor tweaks to service patterns you made, the vast majority of trains will never need the capability.

In past discussions people have suggested a joint replacement of just 444 and 158/9 ‘when they are both due’, simply because a supposed bimode equivalent would be good for Exeter. But the lifespan of the trains just doesn’t fit, 444/450 will be in service 20 years longer than the DMUs.

 

[nw1]

Did you mean  argue? We don't agree!

Ah, sorry, I misunderstood what you were implying here. I thought you meant use the 3x2 for some kind of Salisbury extension of the existing Basingstoke stoppers.
Salisbury fasts/semi-fasts I'd definitely work with some kind of 2x2, for comfort reasons.

If on a network like SWR‘s where they have less than 30 DMUs, but the equivalent of about 325 4 or 5 car EMUs, (counting 701/0 twice), it would be fairly ridiculous to make a full fleet replacement all bi-mode, no matter what minor tweaks to service patterns you made, the vast majority of trains will never need the capability.

In past discussions people have suggested a joint replacement of just 444 and 158/9 ‘when they are both due’, simply because a supposed bimode equivalent would be good for Exeter. But the lifespan of the trains just doesn’t fit, 444/450 will be in service 20 years longer than the DMUs.

To be fair I wasn't thinking of something like SWR, where fully electric is dominant, and where the 444s are still only mid-life. I am not suggesting SWR fleet replacement!

I was thinking of a smaller network, something like:

Route A - fully-electrified: has fasts and stoppers. Something like the Portsmouth Direct.
Route B - electrified to 80 miles, fasts terminating at the electrification limits, and other fasts extending beyond. Also stoppers extending out to 40 miles. This would be something like Salisbury and Exeter if we imagine electrification to Salisbury, only.
Route C - electrified to 80 miles. Stoppers, plus fasts, where all fasts extend beyond the electrification limit

So on Routes A and B, you have fasts on fully-electrified track, but on B and C, fasts on partly-electrified track. All three routes have stoppers.

I picked this kind of scenario because I thought it would be most interesting, regarding the question.

 

[I'm here now]

Some class 769s should do your first type of traffic.

Ah, sorry, I misunderstood what you were implying here. I thought you meant use the 3x2 for some kind of Salisbury extension of the existing Basingstoke stoppers.
Salisbury fasts/semi-fasts I'd definitely work with some kind of 2x2, for comfort reasons.



To be fair I wasn't thinking of something like SWR, where fully electric is dominant, and where the 444s are still only mid-life. I am not suggesting SWR fleet replacement!

I was thinking of a smaller network, something like:

Route A - fully-electrified: has fasts and stoppers. Something like the Portsmouth Direct.
Route B - electrified to 80 miles, fasts terminating at the electrification limits, and other fasts extending beyond. Also stoppers extending out to 40 miles. This would be something like Salisbury and Exeter if we imagine electrification to Salisbury, only.
Route C - electrified to 80 miles. Stoppers, plus fasts, where all fasts extend beyond the electrification limit

So on Routes A and B, you have fasts on fully-electrified track, but on B and C, fasts on partly-electrified track. All three routes have stoppers.

I picked this kind of scenario because I thought it would be most interesting, regarding the question.

Class 769s for route B&C - they're capable of 3rd rail, which I haven't seen on any other trains, for the Exeter services. They could be modified in a class 159 style to accommodate Intercity travel.