Great Western Coffee Shop

A "High level" question about electric freight haulage on UK railways - triggered by an article in Railway Gazette (https://www.railwaygazette.com/uk/class-90s-support-freightliner-decarbonisation-objectives/57095.article)


What proportion of freight is electric hauled on the UK network at present?

How does electric haulage work when loading/unloading containers or stone?

Where is the infill needed?  `

Scope for more bimode for freight?

I'm coming from real basics on this one - "ask a silly question" day, but really "ask a newbie question set that is far from silly".  Anyone help me by addressing it?

I can’t give you percentages but conversations with others suggest the amount of rail-borne freight in the UK is quite low compared to many other countries. One of the reasons for this is the relatively short distances much of it travels.

Having observed the number of diesel hauled freight under the wires, however, I have thought for some time that perhaps a way needs to be devised to use bi-modal locomotives. As this hasn’t been done already, when so much bi-modal passenger stock exists, leads me to the conclusion that it isn’t an easy thing to do.

Does perhaps the heavier loading of freight trains have something to do with it?

There isn’t enough physical space in a normal GB gauge loco to include a big enough Diesel engine and generator along with all the electrical stuff you’d need anyway, including a pretty massive transformer.

This is why the class 88 only has short range slow speed diesel capability, what’s known as a “last mile diesel”.

Maybe they could do it in a lengthened but articulated loco, perhaps with three bogies...

Paul

It's a bit different the other way round. If you build a powerful electric loco, and the available supply and motor ratings allow that to be a lot more powerful than a diesel, it's too light to give the adhesion you need. You can avoid the lightweight bits used on passenger trains, and older heavier designs may well be more efficient, but it's still hard to get enough weight. So you may as well put in a small diesel - it's a better selling point than a lump of concrete. But it is still only a small diesel.

I'm not sure at what point axle loading becomes the factor that limits the worthwhile power. After all, big four-axle wagons have high axle loads anyway. But I have wondered if it makes more sense to use locos in pairs, either permanently coupled (allowing sharing of electric and diesel bits) or not (and of one or two kinds). Of course in much of the world, where freight trains are very much longer and heavier, multiple locos is the norm.

One problem is that docksides and other freight terminals often can not be readily electrified due to the presence of cranes, gantries, and overhead conveyers.
Attaching a diesel engine for such circumstances finds little favour as cost, complexity and risks of delay are increased.

A hybrid locomotive that is primarily 25 Kv powered but with limited battery or diesel power would seem advantageous. A few hundred horsepower of diesel should be able to move the same weight as several thousand horsepower of electric power, but only at very low speeds. (at low speeds the limit is adhesion, not installed power)

Another more radical suggestion is to permanently couple together a diesel and an electric locomotive, forming in effect a single articulated bi-mode loco.
This would not be a simple case of multiple operation, but both units would be modified to improve performance.

In diesel mode, the diesel unit would provide traction power to the motors in the electric unit. At low speeds or when starting, this would roughly double the tractive effort due to more weight carried on motored axles.

In electric mode, the electric unit would power the motors in the diesel unit, thereby again increasing low speed tractive effort. If the existing transformer in the electric unit can be uprated (forced cooling ?) or replaced by a larger capacity transformer, then the total continuous power output can be increased. No uprating of traction motors required as the total power is now spread between the motors in both units.
In electric mode, auxiliary power would be supplied to the diesel unit so as to keep the engine warm, the batteries fully charged, and heat or air condition the drivers cab.

A traction current jumper would be required between the two units, and the inner cabs taken out of use, or even removed.
A trial could be conducted making use of existing locomotives. If successful then new build bi-mode articulated units could be built. For main line use I suspect that an articulated design would be required, I doubt that a single locomotive of acceptable weight and length could incorporate both diesel and electric equipment of sufficient power for heavy trains at 60MPH or more.

For very low speed operation, a small diesel engine could probably be added to an existing design of electric locomotive.

The following (ill informed?) thoughts-

1 - What is the usual weight of container trains? I am familiar with the long mineral trains running past me at Reading with their gross and tare weights marked on each wagon. Could electric locos cope perfectly adequately with them, or are they still heavy enough to cause adhesion problems?

2 - What would be the impact of splitting the current long heavy and relatively slow diesel hauled trains and replacing them with more frequent faster but shorter electric trains?

3 - If Freightliner can persuade NR to infill gaps - perhaps from Felixstowe to Birmingham, Southampton to Birmingham and connections to Immingham and the Trent Valley could all be on the list, this would benefit others as well (dream on?)

4 - And if it does all happen, there will be plenty of redundant class 66s to propel the containers under the cranes to and from the docks without OHL.

Glad to see at least 23 class 90's might have a future.

If I were FL, I would look at a new build of an unpowered vehicle like:

http://www.rvp-ltd.org.uk/projectx/

and commission a design for fitting it with an MTU diesel alternator set (or two!), common to other units such as the 802's, with a SR style power train line connection to the locomotive.

The Brake Tender profile is low enough for sufficient view ahead, so wouldn't need running round..

However, I wouldn't inflict an IEP seat on the driver!

Just a thought in lock-down.

OTC

1 - You can make electric locos as heavy as you need, the addition of concrete ballast weights, however its unlikely needed; modern 3 phase A/C traction motors and power control allows electric locos to haul heavy freight.  The limitation is the max current than can be drawn from the OLE.  There are some issues on the WCML North of Preston and over the boarder with circuit breaker tripping's due to the double headed 90's
The UK operates a mixed traffic railway, and has done for over a centaury, this a compromise between the need for high speed over heavy freight.

2 - efference the FoC wants to put a traction unit on the head of the train that will do the entire trip with as few crew changes as possible, so a diesel loco for a Scotland to Dollands Moor trip can make more sense to them than uncoupling and coupling locos at Wembley

3 - UK PLC or should I say UK Government need to decide that is where it wants to spend UK tax payers money, NR does not fund enhancements it would be up to the FoCs to make the case to DfT which I am sure NR would support, the ToCs would need to buy into it as well local Authorities and business along the entire route especially if the electrification work leads to disruption, noise etc where there is no local benefit 

I thought that was what the Cl92 were for. To avoid the change at Wembley

Perhaps the link below might help. Figure 2.1 in Section 2, p 17, gives a map of the required network. P19 gives a road/rail comparison. P 20 gives total annual movements.

Thanks for Tuesday, Grahame, and our splendid companions.

OTC


https://www.networkrail.co.uk/wp-content/uploads/2017/04/Freight-Network-Study-April-2017.pdf

Perhaps some infill electrifiction around London such as:

Acton - Acton Wells
Acton Wells - Mitre Bridge Jn/WCML
Acton Wells - Cricklewood (Neasden?)
Acton Canal Wharf - WCML
Carlton Road Jn - Junction Rd Jn
Is spur to RCML electrified?

Kew Triangle from NL - Hounslow Loop (Class 92s)

They were, not fully utilised as there are limited routes in Kent they can be used on due to the high current.

I think that the problem is in the specification of the class 92. 4MW off the third rail!

What might have been done is to provide emulator software like the class 91's (they can pretend to be any of the class 8X's!) so that they could substitute easily. If a 92 could pretend to be one or perhaps two 73's at most....

There's something called conductor line index, basically one unit per EE507 /185kW motor, so a 12 car unit = 12 (a REP consist = 14), a 73 = 8. The maximum allowed was 16 - a 92 powering would be over 32!

Perhaps there turned out to be too little freight to bother.

OTC

Basically yes.

There are areas in the Southern where double head 73 on third rail is not permitted.

The typical route setting (DC Protection setting) is for 4kA (3MW) High current railway can go to 6kA (4.5MW) the former Eurostar routes are high current railways.

High current railway needs to have 4kA rated circuit breakers with impedance protection the old falling voltage protection is not adequate, the track feeder cables need to be doubled to two 1000mm sq aluminium cables and the hook switches removed.  The rectifiers also need uprating to 3.5MW class G

There are still a lot of the older 2.5kA rated DC circuit breakers on the network these in the most part are ok at 4kA route setting

You can see why people think 25kV OLE is the future

Agreed, but there is still a limitation on the current draw through the OLE, 300A 7.5MW which is the typical rating, bare in mind OLE electrical section are much longer than DC so the number of trains in section become the limit

As the channel tunnel only generated about 20% of the freight forecast, perhaps we should look to Southampton's 21 daily departures, many times that of Dollands Moor.

The idea of 25kV to Basingstoke was a very narrowly focused idea, neglecting the existing dc infrastructure. This dated firstly from the 1967 Pirbright Jn (a reasonable boundary for local trains) - Bournemouth dc scheme and was/is questionable for such a fast, long, high capacity line and has limitations in  powering services at its extremity. Wiring it would involve about c300km of track, £600M, and would also need to go North from Didcot.

Decarbonising freight means sorting out lots of other services.

Lateral thinking needed.

OTC

Southampton deals mainly with deep sea container traffic the Channel Tunnel deals mainly with "local" European freight which tends to be road hauled; there are plans to repurpose Dollands Moor into RoRo terminal for ET the haulier drops off / collects a trailer from the RoRo terminal, this saves the need for driver to travel with the load.   

There are few direct fright through the Tunnel and on to HS1.