North Downs line electrification

[Feathers44]

Clockwork! Now there's a thought for discontinuous electrification.

Now you're winding us up...

As someone who crosses the line at Betchworth twice a day, driving, it always surprises me just a) how far the station is from anything useful and b) how really infrequent the service is. Even if I have to stop, 50% of trains just thunder on past.

Admittedly, this is probably another chicken and egg situation like the Overground or the Croydon trams. Give people a better service and more people will begin to rely on it. (I suspect if BR had run more trains to Croydon, the trams may never have materialised.)

 

[Philip Phlopp]

Clockwork! Now there's a thought for discontinuous electrification.

GKN's flywheel hybrid system, effectively.

It might even be possible to do something with that, replacing the concrete ballast Electrostars carry when set up for DC, but there's the existing Class 379 IPEMU design, so that's the way to go.

The distances involved aren't too dramatic, 32 miles are not electrified, in various sections, which suits the 48 miles range the Class 379 has to play with.

it might well be worth fitting a battery pack to one of GWR's incoming Class 387 units and trying it out to see if it's possible to run on a DC/battery setup.

The downside to that is you only get DMU performance on battery power, but it removes a source of emissions around Reading and at Gatwick, and allows better flighting of the stock around other electric trains, where acceleration becomes consistent.

 

[FenMan]

Claims the service is infrequent. Well on Sundays there use to be one fast service an hour and one additional slow service every two hours. This was reduced to the fast service being slow from radon to Guildford one hour and then gast and then fast reading to Guildford and slow Guildford to Gatwick the next hour.

Why did they do this if they service was to infrequent or is it the case that it's only on Mondays to Saturdays that it's infrequent?

Sent from my SM-G925F using Tapatalk

Wasn't it a DfT decision to save money?

I don't know about usage east of Guildford, but the NDL Sunday services are frequently (very) full and standing heading to and from Reading during Sunday shopping hours. The old service pattern - 1tph semi-fast to/from Gatwick and 1tp2h stopper to/from Redhill - worked and should be reinstated, but no one seems to want to address this.

 

[Bald Rick]

It might even be possible to do something with that, replacing the concrete ballast Electrostars carry when set up for DC, but there's the existing Class 379 IPEMU design, so that's the way to go.

The distances involved aren't too dramatic, 32 miles are not electrified, in various sections, which suits the 48 miles range the Class 379 has to play with.

it might well be worth fitting a battery pack to one of GWR's incoming Class 387 units and trying it out to see if it's possible to run on a DC/battery setup.

The downside to that is you only get DMU performance on battery power, but it removes a source of emissions around Reading and at Gatwick, and allows better flighting of the stock around other electric trains, where acceleration becomes consistent.

Spot on. I'd have a tenner on this happening at some point in the next 5 years or so. I know some of the TOC owning groups have been looking into the principle.

 

[jimm]

The old service pattern - 1tph semi-fast to/from Gatwick and 1tp2h stopper to/from Redhill - worked and should be reinstated, but no one seems to want to address this.

Really? The following is taken from stakeholder presentations given by GWR last April

May 2017 onwards
There will be 20 extra services on the line – made possible by the cascade of additional rolling stock from the Thames Valley (subject to electrification) and infrastructure changes
We will operate an additional second semi-fast hourly service between Reading and Gatwick. This will replace the peak only Shalford shuttles. The existing semi-fast Gatwick - Reading service and stopping Redhill -Reading services will be retained. The enhancement recognises the importance of the Gatwick market Stations benefitting from increased frequency will include Wokingham, Guildford, Dorking Deepdene, Reigate, Redhill and Gatwick Airport

Weekday number of trains
December 2014
Gatwick - Reading 39
Stopping Redhill - Reading 29
Shalford - Reading 8
Total 76

December 2017
Gatwick - Reading 67
Stopping Redhill - Reading 29
Shalford - Reading 0
Total 96

Spot on. I'd have a tenner on this happening at some point in the next 5 years or so. I know some of the TOC owning groups have been looking into the principle.

People may have been looking at it - GWR said as much in connection with the North Downs line last year - but they may also have been looking at the analysis Modern Railways did of the likely cost of such trains over their lifetime - and the numbers weren't pretty. The Class 379 trial showed it was technically feasible but that's a different matter from being affordable.

 

[DerekC]

GKN's flywheel hybrid system, effectively.

It might even be possible to do something with that, replacing the concrete ballast Electrostars carry when set up for DC, but there's the existing Class 379 IPEMU design, so that's the way to go.

The distances involved aren't too dramatic, 32 miles are not electrified, in various sections, which suits the 48 miles range the Class 379 has to play with.

it might well be worth fitting a battery pack to one of GWR's incoming Class 387 units and trying it out to see if it's possible to run on a DC/battery setup.

The downside to that is you only get DMU performance on battery power, but it removes a source of emissions around Reading and at Gatwick, and allows better flighting of the stock around other electric trains, where acceleration becomes consistent.

I make it 29 miles from a quick Quail. I love the concept of the IPEMU and it is a great solution, but it's still looking for a problem to solve and I am not sure this is it. Its day will come when diesel (or diesel plus carbon tax) really does get uneconomic. But then won't we just electrify?

 

[HSTEd]

Doubtful, electrification costs a fortune.
A ~900vDC supply at a station and a few dozen metres of sheathed third rail will be cheaper in the extreme.

 

[Philip Phlopp]

I make it 29 miles from a quick Quail. I love the concept of the IPEMU and it is a great solution, but it's still looking for a problem to solve and I am not sure this is it. Its day will come when diesel (or diesel plus carbon tax) really does get uneconomic. But then won't we just electrify?

I've 32 miles to be electrified, it might not be 32 miles which aren't electrified, with overlaps etc, it could be less for trains running.

IPEMU on the North Downs Line would almost certainly be accompanied by committed electrification. It's unlikely to feature as a straight diesel replacement with an open ended commitment to battery use because of the life expectancy of the battery packs.

 

[FenMan]

Really? The following is taken from stakeholder presentations given by GWR last April

I was talking about the Sunday service. No mention of that in the stakeholder presentation.

 

[edwin_m]

Doubtful, electrification costs a fortune.
A ~900vDC supply at a station and a few dozen metres of sheathed third rail will be cheaper in the extreme.

The IPEMU was only for 25kV, where much higher energy transfer rates are possible, and even then needed to spend a large proportion of its duty cycle under OLE to charge the batteries as well as run the motors. Use with very intermittent third rail raises a whole host of questions about how much time and how much current would be needed to grab enough charge at a station to get to the next one. There is probably a choice between lengthening the timetable and welding the train to the rail! Not to mention the question of trains not serving all the stations.

 

[jimm]

I was talking about the Sunday service. No mention of that in the stakeholder presentation.

If they think a 25 per cent increase in services on weekdays is worthwhile, I'd expect some sort of increase at the weekends is also a distinct possibility, given there was a also a general pledge on increased capacity for the route. Even if you just had one extra Turbo set in traffic that would be a clear improvement.

 

[Philip Phlopp]

The IPEMU was only for 25kV, where much higher energy transfer rates are possible, and even then needed to spend a large proportion of its duty cycle under OLE to charge the batteries as well as run the motors. Use with very intermittent third rail raises a whole host of questions about how much time and how much current would be needed to grab enough charge at a station to get to the next one. There is probably a choice between lengthening the timetable and welding the train to the rail! Not to mention the question of trains not serving all the stations.

It's been a while and my memory of IPEMU is increasingly hazy, but from what I remember of the unit, the battery charger inverter was run off the main bus, as I recall, and as a result can be fed from both AC or DC electrification systems.

 

[edwin_m]

It's been a while and my memory of IPEMU is increasingly hazy, but from what I remember of the unit, the battery charger inverter was run off the main bus, as I recall, and as a result can be fed from both AC or DC electrification systems.

That would seem a logical thing to design it. However it was only ever trialled on AC as far as I know, and I don't think 379s are fitted with shoes. As modern EMUs tend to be current-limited on the third rail I suspect the limits imposed by the infrastructure would make it much slower to charge on third rail.

 

[JamesRowden]

That would seem a logical thing to design it. However it was only ever trialled on AC as far as I know, and I don't think 379s are fitted with shoes. As modern EMUs tend to be current-limited on the third rail I suspect the limits imposed by the infrastructure would make it much slower to charge on third rail.

It is the battery which primarily limits the rate at which battery trains can be charged. Charge the battery faster and the energy capacity (the total energy that the battery is capable of storing) reduces faster and therefore the battery requires replacing more frequently, therefore producing additional costs.

 

[Philip Phlopp]

That would seem a logical thing to design it. However it was only ever trialled on AC as far as I know, and I don't think 379s are fitted with shoes. As modern EMUs tend to be current-limited on the third rail I suspect the limits imposed by the infrastructure would make it much slower to charge on third rail.

The Class 379 is still a dual voltage design, which is why it was chosen.

Third rail isn't my area, Bald Rick will know I'd guess, but there's probably enough spare capacity on the electrified sections of the North Down to allow DC EMU performance and for battery charging to take place.

You'll be lucky if the battery charger consumption is equivalent to one traction motor.

 

[Bald Rick]

More than enough; a train on this line is only drawing full power about 30% of the time. So plenty of opportunity on the electrified bits to use the other 70% to charge the batteries. Regen helps too.

 

[edwin_m]

So it might be possible to use a battery EMU with partial electrification of the North Downs, but unlikely if the "partial" was as little as a bit of third rail in each station.

 

[RichardN]

So it might be possible to use a battery EMU with partial electrification of the North Downs, but unlikely if the "partial" was as little as a bit of third rail in each station.

Isn't it partially electrified anyway? Reigate to Gatwick, Guildford to near Aldershot, then the last bit to Reading.

 

[greaterwest]

Isn't it partially electrified anyway? Reigate to Gatwick, Guildford to near Aldershot, then the last bit to Reading.

Reading to Wokingham, Aldershot South Jn to Shalford Jn, Reigate L/C to Gatwick to be precise.

 

[Philip Phlopp]

Reading to Wokingham, Aldershot South Jn to Shalford Jn, Reigate L/C to Gatwick to be precise.

And with the way a battery IPEMU would operate on the North Downs line, it benefits from longer continuous operation on third rail, with Wokingham-Reading-Wokingham and Reigate-Gatwick-Reigate on each round trip.

 

[Bald Rick]

And with the way a battery IPEMU would operate on the North Downs line, it benefits from longer continuous operation on third rail, with Wokingham-Reading-Wokingham and Reigate-Gatwick-Reigate on each round trip.

Not forgetting it can be charging at full power draw whilst it is stationary at Reading or Gatwick/Redhill.

And there's another thing in its favour. For third rail systems now you need security of supply in a 'first emergency feeding' scenario, ie if any one substation trips out, the immediately adjacent substations can pick up the load without any restriction on power draw. In practice this means a HV feeder cable parallel to the line, with a substation or switching station (Track Parallelling Hut) at the end of the electrification to feed that 'end' if the next substation along goes off line. This is all the expensive stuff in a DC electrification. The con rail itself is relatively cheap.

With an IPEMU, that security of supply is not so critical, as the train can get itself across a gap. So the conductor rail can be extended a short distance from the existing end of the electrification (perhaps a mile or so) without the need for the expensive parallel HV route or another substation / TP Hut. Thus making the non-electrified gap a couple of miles shorter.

Under normal operation, the IPEMU sees the extended con rail as a normal con rail, and draws power accordingly. If the last substation goes off line for any reason, then the last mile is dead, and the IPEMU has to get the extra mile on battery.

Similarly, a short electric 'island' could be provided with only one substation and no back up, to cover a couple of miles if the total distance off the juice was at the limit of the battery. The best example of this would be Uckfield to Buxted.

All perfectly doable. And much cheaper than full electrification. Not, however, cheaper than diesel trains when oil is $45 a barrel.

 

[Philip Phlopp]

Not forgetting it can be charging at full power draw whilst it is stationary at Reading or Gatwick/Redhill.

And there's another thing in its favour. For third rail systems now you need security of supply in a 'first emergency feeding' scenario, ie if any one substation trips out, the immediately adjacent substations can pick up the load without any restriction on power draw. In practice this means a HV feeder cable parallel to the line, with a substation or switching station (Track Parallelling Hut) at the end of the electrification to feed that 'end' if the next substation along goes off line. This is all the expensive stuff in a DC electrification. The con rail itself is relatively cheap.

With an IPEMU, that security of supply is not so critical, as the train can get itself across a gap. So the conductor rail can be extended a short distance from the existing end of the electrification (perhaps a mile or so) without the need for the expensive parallel HV route or another substation / TP Hut. Thus making the non-electrified gap a couple of miles shorter.

Under normal operation, the IPEMU sees the extended con rail as a normal con rail, and draws power accordingly. If the last substation goes off line for any reason, then the last mile is dead, and the IPEMU has to get the extra mile on battery.

Similarly, a short electric 'island' could be provided with only one substation and no back up, to cover a couple of miles if the total distance off the juice was at the limit of the battery. The best example of this would be Uckfield to Buxted.

All perfectly doable. And much cheaper than full electrification. Not, however, cheaper than diesel trains when oil is $45 a barrel.

I was thinking much the same, but at the same time, wouldn't want to count on the two 15 minute turn around periods being available on a day to day basis when there's late running.

The question I'd guess with late running is do you miss stops to make up time and provide 15 minutes of on juice recharging, or do you plan for missing out on one or two 15 minute charging periods in your battery capacity, whereby you allow the battery to drain more than it's recharged if it doesn't have the two 15 minute periods at Reading and Gatwick, and it charges more than it needs if the two 15 minute periods are available (which would cover the loss of the two recharging periods in a previous circuit between Reading and Gatwick and get the battery back to being fully charged).

Extending third rail when there's no additional switchgear needed was another thought, I'd even said a little prayer of forgiveness to the track circuit gods.

 

[hwl]

I was thinking much the same, but at the same time, wouldn't want to count on the two 15 minute turn around periods being available on a day to day basis when there's late running.

The question I'd guess with late running is do you miss stops to make up time and provide 15 minutes of on juice recharging, or do you plan for missing out on one or two 15 minute charging periods in your battery capacity, whereby you allow the battery to drain more than it's recharged if it doesn't have the two 15 minute periods at Reading and Gatwick, and it charges more than it needs if the two 15 minute periods are available (which would cover the loss of the two recharging periods in a previous circuit between Reading and Gatwick and get the battery back to being fully charged).

Extending third rail when there's no additional switchgear needed was another thought, I'd even said a little prayer of forgiveness to the track circuit gods.

Replacing the induction motors with permanent magnet ones to improve low speed regenerative braking looks interesting and it would help extend the range slightly and reduce the penalty for stopping.

A few small 3rd rail extensions where they could be easily fed like Shalford and Ash - Farnborough North would help battery operational flexibility.

 

[Deepgreen]

All very interesting but also all just speculation as clearly none of this will ever happen if the business case is as poor as has been pointed out on this thread already. It's somewhat frustrating that technical solutions such as battery/electric hybrid units, which seem more or less exactly right for this situation will not be implemented because the pure financial case is seemingly absent. However, if the current train lengths and frequencies have to be maintained then the only benefit to be derived would be slightly newer rolling stock. Without re-signalling, platform extensions, etc., the same old three car trains at an absolute maximum of 3TPH will have to continue ad infinitum. The other issue would be the lack of opportunuities/paths (or so we are told) for through workings, making electrification pointless.

 

[Taunton]

So the conductor rail can be extended a short distance from the existing end of the electrification (perhaps a mile or so)

Surely the 25Kv zealots at NR who are dead against any third rail extension would not allow even this; the mile extensions would each be required to use 25Kv overhead

 

[GRALISTAIR]

Surely the 25Kv zealots at NR who are dead against any third rail extension would not allow even this; the mile extensions would each be required to use 25Kv overhead

Looks like you said that slightly tongue-in-cheek but I was thinking exactly the same. Even our erstwhile engineer(s) on this thread are known to really want 25 kV AC OHLE.

 

[Tio Terry]

Surely the 25Kv zealots at NR who are dead against any third rail extension would not allow even this; the mile extensions would each be required to use 25Kv overhead

I think you need to look further than Network Rail. The ORR are not very keen on extending 3rd rail electrification and the Energy Technical Standard for Interoperability says that, for 3rd rail systems, Network rail can apply it's National Network Technical Rules for the maintenance, renewal and enhancement of EXISTING systems. It does not allow the installation of new systems other than minor infills. I doubt the ORR would consider North Downs a minor infill!

 

[Bald Rick]

I think you need to look further than Network Rail. The ORR are not very keen on extending 3rd rail electrification and the Energy Technical Standard for Interoperability says that, for 3rd rail systems, Network rail can apply it's National Network Technical Rules for the maintenance, renewal and enhancement of EXISTING systems. It does not allow the installation of new systems other than minor infills. I doubt the ORR would consider North Downs a minor infill!

But of the infills possible in 3R land, this is the most minor!

(I'm not counting the Kew curve).

 

[HowardGWR]

This is most interesting. Let's take a step back. The chief reason for establishing strategic comumunications between Reading and Gatwick, is the future of Gatwick as a strategic airport. There are other reasons for North Downs update that include better connectiviy fom Brighton and commuting capacity improvements.

Staying with the first strategic issue, direct links from the Midlands and Wales / West of England mean that trains would need to wizz through Reading onto the North Downs link and that would indicate dual units that can can use 25k overhead and third rail 750 DC,

Thus a pragmatic solution could see a competition between bi-modes and the dual volyage units, for use over that trajectory. I am just pointing out that it is the future strategic use of Gatwick, with its possible extension to two runways in 2019 (end of the covenant), that is very important in deciding railway enhancement issues.

 

[Class 170101]

I was thinking much the same, but at the same time, wouldn't want to count on the two 15 minute turn around periods being available on a day to day basis when there's late running.

The question I'd guess with late running is do you miss stops to make up time and provide 15 minutes of on juice recharging, or do you plan for missing out on one or two 15 minute charging periods in your battery capacity, whereby you allow the battery to drain more than it's recharged if it doesn't have the two 15 minute periods at Reading and Gatwick, and it charges more than it needs if the two 15 minute periods are available (which would cover the loss of the two recharging periods in a previous circuit between Reading and Gatwick and get the battery back to being fully charged).

How about just swapping out the unit?

One would hope the same type of unit would run semi fast services between London and Reading (not Crossrail services) and between Reading and Gatwick. Therefore the unit would have a charge with a return trip under the OLE between Paddington and Reading.