Think that’s it. Unless you close Severn Beach and divert services round the Henbury loop, any sensible continuation of Henbury services westwards is going to have significant impacts on those two crossings.
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Future of the GWR electrification
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Annetts key
Established Member
The three road level crossings are:
Avonmouth Dock Junction - West Town Road.
Avonmouth Station - Gloucester Road, somewhat busy, but only local traffic.
St. Andrews Junction - King Road - main docks entrance and by far the busiest crossing for road vehicles.
Currently there is no provision for a train terminating at Avonmouth Station to turn back north.
brad465
Veteran Member
Perhaps the DfT could approve a Go-Op operation in the area and then make them crowdfund the cost to have those crossings upgraded
The other alternative if it was somehow cheaper/easier is to have a station at Chittening, that acts to serve the northern industrial estates and act as an interchange for Severn Beach and Avonmouth.
There is currently a train that terminates at Avonmouth - I had always presumed the Loop proposal would see this service extended.
Of course whether running it "around the loop" would be more useful than increasing service to St Andrews Road and Severn Beach to half-hourly, I don't know.
Of course whether running it "around the loop" would be more useful than increasing service to St Andrews Road and Severn Beach to half-hourly, I don't know.
Annetts key
Established Member
You could keep the Severn Beach service. The current Avonmouth terminator would be the service you would extend through to Henbury.
Yes, the level crossings would have more trains travelling over them, but I don't think an extra train per hour is going to make that much difference.
In an ideal world (ie one where awkward things like track and junction capacity didn’t feature), I’d go for Temple Meads (or beyond in all 3 cases) - Clifton Down - Severn Beach, alternating with TM - Clifton Down - Henbury - Bristol Parkway and Temple Meads - Ashley Down - Henbury
== Doublepost prevention - post automatically merged: ==
Whoever now operates the docks did, though.
zwk500
Veteran Member
As would I, although the TM-Henbury service would be at least 2tph.
We’re getting dangerously speculative….
It would be a shame if the Henbury station isn't built with at least passive provision for becoming a through station.
Operationally and technically, the difference is negligible. The procedures and engineering requirements are the same.
I agree. A secondary line cutting across from one mainline trunk to another is a very plausible use case.
Annetts key
Established Member
Project Churchwood (the complete renewal of the GWR diesel fleet) is very likely to use battery electric multiple units (BEMU).
New overhead line equipment (OLE) will therefore be needed to support their operation.
An extension of the current OLE from the existing OLE on the Charfield lines near Westerleigh Junction to Berkley Road is proposed. At Bristol, part of sidings at Pyle Hill (just west of BTM) is also proposed to be electrified.
Filton Bank: electrification is a stand-alone project that is currently at strategic business case submission. This would be the installation of OLE from Stoke Gifford/Patchway to Dr Days Junction.
Strangely, there do not appear to currently be any plans to install OLE at Bristol Temple Meads Station under either of the above project proposals.
New overhead line equipment (OLE) will therefore be needed to support their operation.
An extension of the current OLE from the existing OLE on the Charfield lines near Westerleigh Junction to Berkley Road is proposed. At Bristol, part of sidings at Pyle Hill (just west of BTM) is also proposed to be electrified.
Filton Bank: electrification is a stand-alone project that is currently at strategic business case submission. This would be the installation of OLE from Stoke Gifford/Patchway to Dr Days Junction.
Strangely, there do not appear to currently be any plans to install OLE at Bristol Temple Meads Station under either of the above project proposals.
Showing my ognorance here: Why is OHLE needed to support battery operation?
OHLE per se isn’t- but you’ve got to have some way of charging the batteries and doing it while the train is moving has quite a few advantages.
Annetts key
Established Member
If the trains will already be operating under some existing OLE, it makes sense to add in some extra OLE to allow the battery to be recharged at more locations / lines.
The overall range of a battery powered train depends on how long and how often it can be charged by an external electricity supply.
And of course if the sections of OHLE “happen” to be bits where power requirement will be high (ascending Filton Bank for example) it cuts down on battery drain.
Possibly packaged with Chippenham - Bristol later, perhaps after final west end layout changes at Temple Meads? Likely not necessary for the partially wired scheme for battery trains, but useful in the long run to maintain off-wire battery range elsewhere and to cut pollution from bi-mode trains.
zwk500
Veteran Member
New battery stock would almost certainly be better than the Turbos. Although whether it'd be better than a new DMU such as a FLIRT I don't know.
Depends how much grunt you put in the power pack! I rode a FLIRT in the Cardiff valleys a few weeks ago for the first time. Acceleration on battery was sprightly, and to me was indistinguishable from when under wires.
Trainbike46
Established Member
A FLIRT on electric has much better acceleration than the same FLIRT on diesel, and I would expect a FLIRT on battery to be more similar to a FLIRT on OHLE, so presumably so.
And this confirms it!
Depends how far it'll have to go on a charge, I'd have thought. If it's only a short hop then more energy will be available.
Snow1964
Established Member
It rather depends on the power rating of the trains.
The current diesels generally have 350hp rated engines, (although some of that is powering other things, eg generators, air conditioning), and as engines are not normally thrashed at full power rating, probably got nearer 200-250hp max actually accelerating the train per vehicle.
Many modern suburban electric trains have motors that are rated at nearer 500hp per vehicle, and the auxiliaries can draw power without sapping power from the drive motors.
Battery trains are somewhere between the two, unlike drawing power from a feeder wire (where ultimately the power limit is how hot you are prepared to allow it to run, and there will be both a short term and a lower continuous rating reflecting this), the battery might have an output rating. As an example if you have a 500hp motor, but battery can only deliver 400hp then going to be limited by battery.
At this stage there are no published specs of proposed project Churchward trains, so acceleration rates are not known. However most BEMUs in Europe have lower acceleration or top speed on battery than on the wires.
Unless they are fitted with enormous batteries, there is going to be a range vs max power trade off. If they did have huge batteries then a short spell on the wires might not be able to fully recharge them.
In reality is is daft considering batteries for a section like Bristol-Bath-Bathampton with 4-5 trains (sometimes 6 with ECS and freight) per hour. They are better suited to the low frequency sections.
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There's no reason battery trains can't be faster than OHLE (in the practical applied sense) in the medium term. Battery cooling is an increasingly solved problem. The Tesla car batteries/motors can do >1000hp for short periods of time, on a vehicle which is 5% of the weight of a single EMU car.
So there is no reason why battery trains cannot for 10-60s initial acceleration put out an insane amount of power to get the train going, more so even than OHLE could realistically do given substation constrains.
I expect over the next 5-10 years we'll see enormous improvement in batteries. Railway industry (understandably) is not at the cutting edge of this, but all the improvements in BEVs will filter down eventually.
Unfortunately the UK rail industry/network rail had multiple chances to get electrification costs down but failed.
So there is no reason why battery trains cannot for 10-60s initial acceleration put out an insane amount of power to get the train going, more so even than OHLE could realistically do given substation constrains.
I expect over the next 5-10 years we'll see enormous improvement in batteries. Railway industry (understandably) is not at the cutting edge of this, but all the improvements in BEVs will filter down eventually.
Unfortunately the UK rail industry/network rail had multiple chances to get electrification costs down but failed.
Well, I'll believe it when I see serious plans for high-speed battery trains.
The thing is that batteries still need to charge, if the length is the OHLE isn't long enough then battery trains aren't going to work.
If the requirements for batteries is that they end back at the wires with limited range, then they increases the risk of things going wrong. For example if you get to the wires with just 10 miles then if there's a fair with the wires that train isn't going further, conversely get then to the worst with 25 miles left, there's a good chance you could get them to the next station even if the wires are off.
HSTEd
Veteran Member
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Every pantograph can pull down 2MW in essentially all conditions, more if the train is moving.
I suspect you'd probably standardise most units at 2MW to reduce transformer weight and avoid any need to control power based on whether the pantograph is moving.
Of course if we get really aggressive we can go to high frequency transformers and cut weight further.......
If you select your charging points properly a surprisingly short amount of overhead wiring can get you a long way.
But I think we will need trains designed from the ground up for this operation to get anywhere.
EDIT:
As a somewhat relevant example for GWR, going from Penzance to St Erth, a significant portion of which is single track, gets you 20 minutes of charging plus layover. Even with a ten minute layover it will be a whole megawatt hour per pantograph.
EDIT #2:
For 11 route kilometres (around 20 track kilometres) you can get to Hayle, providing a wire in the bay for charging the Ives Shuttle at St Erth. The line is within ~1200m of the 132kV Hayle substation which would easily support a suitable Static Frequency Converter.
I suspect you'd probably standardise most units at 2MW to reduce transformer weight and avoid any need to control power based on whether the pantograph is moving.
Of course if we get really aggressive we can go to high frequency transformers and cut weight further.......
If you select your charging points properly a surprisingly short amount of overhead wiring can get you a long way.
But I think we will need trains designed from the ground up for this operation to get anywhere.
EDIT:
As a somewhat relevant example for GWR, going from Penzance to St Erth, a significant portion of which is single track, gets you 20 minutes of charging plus layover. Even with a ten minute layover it will be a whole megawatt hour per pantograph.
EDIT #2:
For 11 route kilometres (around 20 track kilometres) you can get to Hayle, providing a wire in the bay for charging the Ives Shuttle at St Erth. The line is within ~1200m of the 132kV Hayle substation which would easily support a suitable Static Frequency Converter.
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Snow1964
Established Member
I'm not so sure, might be a bit lighter and more tightly packaged for road vehicles. But unless there is a step change in cost of the raw materials, allowing new types of battery then going to be only slightly improved compared to now. You cannot rewrite the chemical properties and laws of physics to get significantly better from similar makeup.
Ultimately, also cannot add too many batteries unless want track unfriendly heavy vehicles (and adding batteries pushes up the purchase cost).
Don’t forget the comparison is between a BEMU and a DMU, and a DMU at gross weight has engine, cooling system, exhaust system with treatment, full fuel tank, etc. To get a track unfriendly BEMU you would be looking at over 10 tonnes of battery per vehicle, which means 40 tonnes on a 4 car unit. That’s enough battery for a comfortable 4-5MWh, and that’s enough juice to take that 4 car unit from Penzance to Newbury… and back.
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