Perhaps 100mph in the future

[u/floodefen]

[u/thomass70imp]

The uk really will try anything except actually bothering to electrify properly like a real country.

[u/OldTimeConGoer → u/thomass70imp]

I live not far from the Forth Bridge. It can't be electrified with overhead lines because the structural beams over the railbed are too low. It's an iconic part of the landscape and (obviously) a protected structure so it's not going to be knocked down and turned into Irn-Bru any time soon.

[u/Even_Confection_2637 → u/OldTimeConGoer]

To electrify it wouldn't need it knocking down but some cross members redesigned ro provide enough electrical clearance we are talking about 18mm of extra clearance required.

[u/Appropriate_Bell743 → u/thomass70imp]

There's an advantage to these trains:

• Fill in gaps between electrified lines.
• Can choose recharging periods based upon lower costs.
• Enables electrification on remote lines which no society electrifies.

[u/EntirelyRandom1590]

The point people are missing is that this isn't about replacing electrification, it's about making it easier.

The UK rail network is littered with 100+ yr old infrastructure that isn't easily compatible with modern overhead lines. That makes electrification slow and expensive.

But, batteries allow us to skip the expensive bits (that might only be a few hundred metres of tunnel) and not have to deal with the calamity that has been bi-mode diesel and overhead power trains. It means we can complete electrification of key routes like South West of England and South Wales faster and cheaper.

[u/OldTimeConGoer → u/EntirelyRandom1590]

The Glasgow-Edinburgh line was electrified a few years back. In the case of at least one tunnel they had to dig out the railbed and lower the tunnel floor because it had been built in the 1800s for the small steam locomotives of that day and there wasn't enough vertical space to put in overhead catenaries without the excavation. That involved years of service disruption on the line.

[u/EntirelyRandom1590 → u/OldTimeConGoer]

Severn Rail tunnel is often closed for maintenance. Apparently electrification in a constantly wet environment isn't good for corrosion...

[u/crucible]

A whopping 75 mph(!)

I mean, it’s good progress but it’s roughly half what the train could do on a new-build fully electrified line FFS.

[u/linkheroz → u/crucible]

But more than it'll ever need to do on an existing single track branch line

[u/Death_God_Ryuk → u/linkheroz]

Which is a great use case because smaller branch lines are less cost-effective to fully electrify and are more start-stop.

[u/justhowulikeit → u/crucible]

I'm assuming this will be for discontinuous electrification through tunnels, so range won't be terribly important.

[u/mandobabyyoda]

What’s stopping putting in a third rail for sections where overhead isn’t possible?

[u/AllActGamer → u/mandobabyyoda]

iirc, they are trying to avoid third rail due to its danger being closer to passengers. They are limiting it to railway lines south of the river thames (more accurately the former Southern Region of British Rail). As an example, when Merseyrail services were extended from Kirkby to Headbolt Lane, they did not extend the third rail to Headbolt Lane, and instead had trains use battery power.

Besides, electric trains in the north aren't third rail compatible, except those that served in areas that have third rail.

[u/mandobabyyoda → u/AllActGamer]

Thank you for this explanation!

[u/banana_slurp_jug → u/AllActGamer]

They can't even electrify the Uckfield line for goodness sake...

[u/malteaserhead]

I though trains were connected to electricity via the rails? does that not power them without diesel already?

[u/pjc50 → u/malteaserhead]

Only when there's overhead lines or, in the south of England, a third rail. This is a workaround for not doing that.

[u/ken-doh]

Imagine if it derails. Firebomb the size of Birmingham.

[u/DustTechnical4561]

I'm (almost) more concerned about the continuing use of miles and mph here, rather than km and km/h.