I don’t understand, there’s no formal announcement here just more speculation.
That was my interpretation too.
I don’t understand, there’s no formal announcement here just more speculation.
I don’t understand, there’s no formal announcement here just more speculation.
There's also a PS at Loch Luichart, but nothing after that to Kyle. The supply to Skye crosses just North of Glenelg.Technically it's from both Beauly and Dounreay - the lines were put in to connect the nuclear reactor at Dounreay, and later various wind farms, to the National Grid. Reportedly the North of Scotland Hydro-Electric Board proposed electrification of the Highland lines to British Rail quite early on in its' existence - it would be interesting to know exactly what was proposed.
Aberdeen - Inverness would be a new commitment but you'd imagine it would be bottom of the priority list of any Seven Cities rolling electrification scheme.
It basically, at that point, becomes an "infill", albeit a rather large one. Any major physical obstacles other than the Aberdeen tunnels?Agreed, but once you have got both ends done the business case or whatever stacks up much better I would think.
Would they ever allow masts over Glenfinnan viaduct and in other scenic bits?
I think you'd still have to step up the voltage to far more than any battery could supply directly, otherwise the current needed for fast charge of a train would be enough to weld the train to the charging equipment. So you'd need a solid state DC-DC converter at the charging station and another one on the train to step it down. If you're doing that then I think it would be much easier to step up and invert the battery voltage to 25kV AC at the trackside, so the train could just use the equipment it needs anyway to charge on standard 25kV sections.A technological aspect that might need to be worked out soon is the way that trains would charge up rapidly. Where 25kV AC is available, it's the natural choice as we know it can handle the highest possible power loads without needing a fundamental re-think. However, on isolated sections of OHLE only usable for recharging rather than running, it's unclear if it's still the best option. Fast charging of cars depends on high-voltage DC going straight into the batteries rather than AC converted to DC in the onboard power electronics. Should we create a standard for high voltage DC overhead power for charging? Using 25kV AC might allow you to get the power transmission you want but then you might an issue when a charging station is powered by trickle grid or renewables into a static battery. In that case it has to convert the static battery DC to 25kV AC for the few metres of conductor, down the pantograph and into the train's electronics, where it's then turned back into DC to charge the batteries. If you're going to use a static battery you don't want to do unnecessary conversions - extra power waste and extra electronics needed at the lineside. Since this would only be for isolated sections requiring battery technology the incompatibility with existing 25kV AC or 750V DC electric stock would be irrelevant.
If they are serious about electric cars etc, then there will need to be improved grid supply to remote locations too. Now I am not suggesting OHLE on the WHL or Kyle - but at least there maybe grid connections to help with the charging etc logistics.
I think you'd still have to step up the voltage to far more than any battery could supply directly, otherwise the current needed for fast charge of a train would be enough to weld the train to the charging equipment. So you'd need a solid state DC-DC converter at the charging station and another one on the train to step it down. If you're doing that then I think it would be much easier to step up and invert the battery voltage to 25kV AC at the trackside, so the train could just use the equipment it needs anyway to charge on standard 25kV sections.
Technically it's from both Beauly and Dounreay - the lines were put in to connect the nuclear reactor at Dounreay, and later various wind farms, to the National Grid. Reportedly the North of Scotland Hydro-Electric Board proposed electrification of the Highland lines to British Rail quite early on in its' existence - it would be interesting to know exactly what was proposed.
Probably not, but if you're relying on batteries you can avoid most of those complications.
A technological aspect that might need to be worked out soon is the way that trains would charge up rapidly. Where 25kV AC is available, it's the natural choice as we know it can handle the highest possible power loads without needing a fundamental re-think. However, on isolated sections of OHLE only usable for recharging rather than running, it's unclear if it's still the best option. Fast charging of cars depends on high-voltage DC going straight into the batteries rather than AC converted to DC in the onboard power electronics. Should we create a standard for high voltage DC overhead power for charging? Using 25kV AC might allow you to get the power transmission you want but then you might an issue when a charging station is powered by trickle grid or renewables into a static battery. In that case it has to convert the static battery DC to 25kV AC for the few metres of conductor, down the pantograph and into the train's electronics, where it's then turned back into DC to charge the batteries. If you're going to use a static battery you don't want to do unnecessary conversions - extra power waste and extra electronics needed at the lineside. Since this would only be for isolated sections requiring battery technology the incompatibility with existing 25kV AC or 750V DC electric stock would be irrelevant.
The line speed on the rural lines will always remain low, so I assume that simpler OHLE structures will suffice. I can see a problem crossing the Rannoch Moor bogs, though.
Doesn't necessarily require fast charging. Cars do it because they don't/can't charge whilst moving.
The extra expense of more complex equipment would cover some length of standard OHLE, & you could always charge whilst on the move. There's also regen braking.
eg. electrify the 58miles of Montrose-Inverurie*, & that covers the power need for accelerating out of Aberdeen & the stations at each end, & about an hours running under OHLE. That gives a long time for charging. (* currently the section with more intensive use)
It's then 30miles to Dundee, which may well be doable on battery.
Even hydrogen trains are electric, so could use OHLE to save on fuel.
The second level is probably how you'd handle the low frequency (<1tph) stretches of the WHL, Far North and Stranraer lines. Here you'd have to make the decision about how much overhead line to provide versus the amount of battery storage required and the rate of charge. If you just put up charging points at stations, you'd need to be able to refill enough power to get to the next charger without requiring a longer stop. When the most difficult/sensitive sections can now be handled by battery power alone, your cost of electrification would be much more linearly proportional to the length of track you want to cover. Time under electrical power is more important than the distance. You'd need to build many kilometres of OHLE to provide the same amount of charging time as a few hundred metres around the station could. Shorter charging sections would indeed necessitate more expensive lineside equipment and power supplies, but you'd save on the cost of installing the OHLE.
I wonder how feasible a half way system would be, where a station, and say the first mile of track either side of the station has OHLE. That would allow charging to occur during station dwell time, and also provide power for the initial acceleration out of a station to get up to line speed, which takes a lot of energy. Obviously steep gradients and increases in line speed would drain batteries just as significantly, but it would provide both increases time charging while (somewhat) reducing the energy required from the battery
Another issue with short sections of OLE around stations (or elsewhere) is supply redundancy. Linking the sections together would need a high voltage cable along the entire route, which is unlikely. So either each electrified section needs dual supplies (which could at a stretch be mains or battery) or the trains need to have the battery capacity to cover two dead sections. With continuous electrification this isn't really a problem because they are designed so if one feeder goes offline the sections can be switched to be supplied from other feeders.
25kV feeders are expensive items, although the current ones are designed to feed a large number of trains. One to feed just one or two trains ought to be cheaper and possibly need a lower voltage supply (for example with rectifiers, DC link and inverters so the load is balanced across the supply phases).
Now I am not suggesting OHLE on the WHL or Kyle.....
In terms of visual impact I am not sure it would be too great unless they were to opt for a GW-type overkill. There is plenty of OHLE in mountainous areas of Europe such as the Alps and Pyrenees, and it is not generally obtrusive.
But you might need GW type masts to ensure the OLE stays up rather than it fall doen in a Scottish Gale. It would be quite exposed there as well and difficult to maintain / repair in case of failure.
Agreed. Don't think we need GWML style because of this. I suppose Rannoch Moor would need something akin to Chat Moss style- but I suppose will not fully be know until/if/when a geological survey is done. Anyway 7 cities will be first so point is moot.It would be almost entirely single track, so the heaviest types of OHLE (multi-track spans) would have no reason to be there. The speed of the trains using the wire would also be pretty low compared to the GWML project.
The mast types used are academic if the foundations are the problem. One shudders to imagine how much concrete would need to be used to get masts up on Rannoch Moor...But you might need GW type masts to ensure the OLE stays up rather than it fall doen in a Scottish Gale. It would be quite exposed there as well and difficult to maintain / repair in case of failure.
Easy enough to sink piles in those conditions they just have to be long / deep larger diameter so a larger vibrating piling head which then needs a bigger excavator (RRV or not) to mount it onThe mast types used are academic if the foundations are the problem. One shudders to imagine how much concrete would need to be used to get masts up on Rannoch Moor...
Driving piles would be a complete non-starter too as the equipment (usually a Movax) would need sufficiently strong ground beneath the rails to drive them, I would've thought.
Easy enough to sink piles in those conditions they just have to be long / deep larger diameter so a larger vibrating piling head which then needs a bigger excavator (RRV or not) to mount it on