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DC+ 3rd rail speed limit

Started by Vladki, May 03, 2020, 09:31:15 PM

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Vladki

Electrification speed limits seem to be inconsistent:
DC = 200 km/h
3rd rail = 200 km/h
DC + 3rd rail = 160 km/h
why is there a lower limit if they are used both? I would expect the same. Or maybe 3rd rail alone was also supposed to allow only 160 km/h?
But then:
AC = 400 km/h
AC + 3rd rail = 400 km/h

fam621

#1
In the UK, the max. speed of each electrification is of the following:
On their own
3rd rail - DC = 160km/h
3rd rail - DC with 4th rail - DC = 160km/h (operating on 3rd rail), 112km/h (operating on 4th rail)
OHLE - AC = 320km/h
OHLE - DC = 160km/h
Mixed
OHLE - AC + 3rd rail - DC = 320km/h (operating on OHLE), 160km/h (operating on 3rd rail)
OHLE - DC + 3rd rail - DC = 160km/h (operating on both)
OHLE - AC + 3rd rail - DC with 4th rail - DC = 320km/h (operating on OHLE), 160km/h (operating on 3rd rail), 112km/h (operating on 4th rail)
OHLE - DC + 3rd rail - DC with 4th rail - DC = 160km/h (operating on OHLE and 3rd rail), 112km/h (operating on 4th rail)

OHLE = Overhead Line, DC = Direct Current, AC = Alternating Current

NoMorePacers

Quote from: thegamer7893 on May 03, 2020, 10:12:02 PM
In the UK, the max. speed of each electrification is of the following:
On their own
3rd rail - DC = 160km/h
3rd rail - DC with 4th rail - DC = 160km/h (operating on 3rd rail), 100km/h (operating on 4th rail)
OHLE - AC = 320km/h
OHLE - DC = 160km/h
Mixed
OHLE - AC + 3rd rail - DC = 320km/h (operating on OHLE), 160km/h (operating on 3rd rail)
OHLE - DC + 3rd rail - DC = 160km/h (operating on both)
OHLE - AC + 3rd rail - DC with 4th rail - DC = 320km/h (operating on OHLE), 160km/h (operating on 3rd rail), 100km/h (operating on 4th rail)
OHLE - DC + 3rd rail - DC with 4th rail - DC = 160km/h (operating on OHLE and 3rd rail), 100km/h (operating on 4th rail)

OHLE = Overhead Line, DC = Direct Current, AC = Alternating Current
You could do 70mph on 4th rail (or 112km/h).

jamespetts

Thegamer - that is interesting. May I ask what the source for that information is?
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fam621

James - This is as according to how fast trains run on those systems irl

Quote from: NoMorePacers on May 03, 2020, 11:03:19 PM
You could do 70mph on 4th rail (or 112km/h).

NoMore - I forgot that A Stock trains use to run at 70mph (112km/h) xD

Sirius

#5
I am challenging the stated speed limit of AC overhead wires. Do you have any sources for that speed limit?
HS1 is designed for a maximum speed of 300 km/h. HS2 operation speed is designed at 330 km/h, maximum speed will however be 360 km/h.
Quote1.63 HS2 is designed to operate at 330kph routinely, with a maximum speed of
360kph. HS2 trains will run up to 177kph on the conventional network. Faster
trains will deliver more frequent and reliable services between more locations
https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/879445/full-business-case-hs2-phase-one.pdf

I did not find any sources explicitly stating a maximum speed for the electrification itself, so the following is about the maximum speed of tracks equipped with a specific electrifications and vehicle maximum speeds under a specific electrification.

Abouth fourth rail:
QuoteWith the old A-stock trains [...] speeds of around 70mph have been allegedly recorded in running service – the allegedly is important, though. None of this is official test conditions...
https://www.citymetric.com/transport/which-london-underground-line-fastest-3322
Official maximum speed of A stock is 70 mph; ~113 km/h


About 750V DC 3rd rail:
160 km/h maximum speed sounds quite reasonable to me as the low Voltage is rather not sufficient to supply a train with enough power to reach 200 km/h or even more.
Any multi electrification train capable of more than 160 km/h seems to be limited to 160 km/h under 750V DC 3rd rail, so it's quite reasonable to assume a maximum of 160 km/h for this type of electrification.
For example class 395 Javelin


About DC, it's more difficult:
Most 1.5 kV DC catenary electrified tracks were replaced by AC or 3rd rail before fast electric trains played a role in the UK.
Technically, both Eurostars can reach speeds of 220 km/h under 1.5 kV DC.
In France such lines exist, e.g. Paris-Bordeaux Railway (not to be confused with LGV Sud Europe Atlantique) is electtrified with 1.5kV DC catenaries for speeeds of 220 km/h.
The fastest speed actually reached in the UK under 1.5 kV DC catenary electrification was 90 mph; ~145 km/h by Class 77 trains, also known as Class EM2 Co-Co

About combination of these:
I did not dig deep into that topic. In the quick run I could not find any tracks permitting faster speeds than (our assumed) maximum speed of the slowest installed electrification.
However, that might be due to the tracks themselves rather than technical or legal restrictions of the combined electrification.

Would be nice to get any sources of railway laws or existing railway lines that have a higher maximum speed than the slowest installed electrification.

NoMorePacers

There are some cases where the line speed is higher than the electrification is designed for. On the Midland Main Line between London St Pancras and Bedford, the diesel trains on that line can reach the maximum line speed (which is 200kph), however the electrification on that line can only support trains going 160kph at most (which has only now become a problem given the plans to run electric trains at a higher speed on that section due to wires reaching further north). Also of note, the GEML just north of Maryland on the fast line has a differential speed limit, where all electric trains can reach 128kph, whereas diesel multiple units are permitted to reach 145kph, due to tensioning in the wires. The conversion of the West Coast Main Line from Mk1 and Mk3a OHLE to the UK1 OHLE equipment was done to make the line 200kph-ready, as neither of the two types could support the increased speed required. There's an interesting document on OHLE that can be read here if you wish to find out further.

In short, I would think that, if it were to be considered, AC OHLE's maximum speed should be dictated by type of variant that the player can purchase if such a level of gameplay were to be added to Extended.

Sirius

Quote from: NoMorePacers on May 06, 2020, 07:39:00 AMThere are some cases where the line speed is higher than the electrification is designed for.
If that's true, we should IMHO set none of electrifications maximum speeds below 200 km/h.
Apart from multi electrification vehicles, the vehicle itself will be the limiting factor anyway. Multi electrfification vehicles currently have their issues anyway, e.g. they can run on any electrification instead of only two.

That means:
AC catenary and AC catenary+DC 3rd rail: 400 km/h
any DC electrification: 200 km/h
optionally, DC caterany 220 km/h, depending on wha texactly it aims to represent.

Quote from: NoMorePacers on May 06, 2020, 07:39:00 AMIn short, I would think that, if it were to be considered, AC OHLE's maximum speed should be dictated by type of variant that the player can purchase if such a level of gameplay were to be added to Extended.
That's what most standard paks actually do. These, however, don't have constraints to differ electrification types, so they don't add combinations of these.

In the long term, I agree, extended should simulate different generations of electrification but that would first require a feature to allow eletrifications only affecting vehicles that actually use these AND a feature to allow placement of multiple different electrifications on a single tile.
Otherwise all these electrification types would blow up the menu.

jamespetts

I have now increased the maximum permitted speed of the slower electrification types to 200km/h.
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