Trivia: Trains that have/had dual mode capabilities but run/ran on one mode most of the time

Krystal · 30 Apr 2026

For example, the 377/5s with Southeastern. They have 25kV OHLE equipment and can pick up overhead power with the pantograph. But it's never used. Therefore the 377/5s only utilise their third rail capabilities because 95% of Southeastern is 3rd rail and not OHLE.
Are there any other trains that are like this? I can think of at least two/three more examples, but I'd like to hear more.

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Sorcerer · 30 Apr 2026

Would the Class 390 count? It's only 25kV overhead but it had an Eco Mode and Boost Mode for performance. If not then I think the Class 350 is another example. Not sure which units (I think /1 maybe?) but I think they could run on both third rail and overhead. I think some early Class 777s were designed for potential overhead line use as well, right? I might be misremembering a few things here.

Bletchleyite · 30 Apr 2026

350/1. Almost never used their third rail capability - only a few of the class did when temporarily used by Southern for the service via Kensington Olympia about 15 years ago.

They only have this capability because they were originally ordered for SWT and were redirected to the WCML.

stadler · 30 Apr 2026

• All 350/1 units are dual voltage but no longer get used on DC. They used to do DC work at SN.

• All 373 units are dual voltage but no longer get used on DC. They used to do DC work before HS1 was built.

• All 375/6 units are dual voltage but have never been used on AC. They used AC under testing after they were built but never again after that.

• All 377/2 units are dual voltage but no longer get used on AC. They used to do AC work at FCC/TL. Also very occassionally they still do AC work when they replace a 377/7 units on Clapham to Watford trains.

• All 377/5 units are dual voltage but no longer get used on AC. They used to do AC work at FCC/TL.

• All 387/1 units are dual voltage but many of them (101-113) no longer get used on DC. They used to do DC work at TL.

• All 387/1 units are dual voltage but many of them (114-129) no longer get used on AC. They used to do AC work at GN/TL.

• All 387/1 units are dual voltage but many of them (130-171) have never been used on DC. They used DC under testing after they were built but never again after that.

• All 387/1 units are dual voltage but many of them (172-174) no longer get used on AC. They used to do AC work at GWR.

• All 387/2 units are dual voltage but no longer get used on AC. They used to do AC work at GN/GWR/TL.

• All 387/3 units are dual voltage but no longer get used on AC. They used to do AC work at C2C/GN/GWR.

• Four 701 units (001/002/501/502) are dual voltage but have never been used on AC. They used AC under testing after they were built but never again after that.

• Two 707 units (001/002) are dual voltage but have never been used on AC. They used AC under testing after they were built but never again after that.

Kite159 · 30 Apr 2026

stadler said:
• Four 701 units (001/002/501/502) are dual voltage but have never been used on AC. They used AC under testing after they were built but never again after that.

• Two 707 units (001/002) are dual voltage but have never been used on AC. They used AC under testing after they were built but never again after that

Are they still dual voltage or did the AC equipment get removed after testing?

brad465 · 30 Apr 2026

Class 365s were a weird one: they were technically dual voltage but could only ever be fitted with one type at a time.

Class 325s also had third rail capability but only ever used it to get to/from Tonbridge's Royal Mail site. However when this closed the third rail capability was never used.

stadler · 30 Apr 2026

Kite159 said:
Are they still dual voltage or did the AC equipment get removed after testing?

That is a good question. I presumed they still had their pantographs but i am not sure. I have quickly searched online but i can not find any photos or videos taken from a footbridge or high enough where you can see the pantograph. But it would seem odd to remove the pantograph. Why go to the effort of removing it when it could easily stay on the units without any issues.

Krystal · 30 Apr 2026

stadler said:
All 373 units are dual voltage but no longer get used on DC. They used to do DC work before HS1 was built.

If I recall correctly the 373s got their shoe gear removed a while ago due to its redundancy.

bramling · 30 Apr 2026

stadler said:
• All 350/1 units are dual voltage but no longer get used on DC. They used to do DC work at SN.

• All 373 units are dual voltage but no longer get used on DC. They used to do DC work before HS1 was built.

• All 375/6 units are dual voltage but have never been used on AC. They used AC under testing after they were built but never again after that.

• All 377/2 units are dual voltage but no longer get used on AC. They used to do AC work at FCC/TL. Also very occassionally they still do AC work when they replace a 377/7 units on Clapham to Watford trains.

• All 377/5 units are dual voltage but no longer get used on AC. They used to do AC work at FCC/TL.

• All 387/1 units are dual voltage but many of them (101-113) no longer get used on DC. They used to do DC work at TL.

• All 387/1 units are dual voltage but many of them (114-129) no longer get used on AC. They used to do AC work at GN/TL.

• All 387/1 units are dual voltage but many of them (130-171) have never been used on DC. They used DC under testing after they were built but never again after that.

• All 387/1 units are dual voltage but many of them (172-174) no longer get used on AC. They used to do AC work at GWR.

• All 387/2 units are dual voltage but no longer get used on AC. They used to do AC work at GN/GWR/TL.

• All 387/3 units are dual voltage but no longer get used on AC. They used to do AC work at C2C/GN/GWR.

• Four 701 units (001/002/501/502) are dual voltage but have never been used on AC. They used AC under testing after they were built but never again after that.

• Two 707 units (001/002) are dual voltage but have never been used on AC. They used AC under testing after they were built but never again after that.

A tenuous one, but class 700/0 units do not use their DC whilst on diagrams solely on the GN side, of which there are a few. From May 18 about 10 units were fully captive on the GN for a while, though after that GTR made an effort to rotate them round.

Paul AC · 30 Apr 2026

stadler said:
• All 373 units are dual voltage but no longer get used on DC. They used to do DC work before HS1 was built.

A gross oversimplification.

All class 373s were built with the capability to run on 750 V dc third rail, 25 kV 50 Hz overhead and 3 kV dc overhead. These were known as "Three Capitals" sets for obvious reasons.

Some were modified to also run on 1.5 kV dc overhead, these were known as "South of Paris" sets.

Some were built for operation "North of London", these had fewer trailer cars, and different power car internal equipment to be compatible with UK 25 kV infrastructure.

Later all had their shoegear removed when they no longer needed to run on 750 V dc third rail.

There were different subclass numbers but to an engineer involved with the project, as I was, what equipment they had was more important than subclass number details.

Even the above is a simplification.....

JohnMcL7 · 30 Apr 2026

The Caledonian Sleeper 73/9's come to mind, they don't have their third rail shoes but I believe they still have that capability but only run on diesel in Scotland.

richard1976 · 30 Apr 2026

Class 399
The class 399 tram/trains used in Sheffield are have both 750V DC & 25 KV AC but have only ever used the 750V.

norbitonflyer · 30 Apr 2026

I think most modern 3rd rail units were built with the capability to operate on AC, so the leasing company had more flexibility if a new franchise decided they wanrted something else. However in most cases the pantographs, transformer and rectifiers were supplied but not fitted.

Very few Class 73s use their 3rd rail capability now - especially those on the Caledonian Sleeper: apart from the Glasgow Subway, on which they can't operate for at least two very good reasons, the nearest 3rd rail to them is at Kirkby.

I don't think the Class 92s use their 3rd rail capability much either

43096 · 30 Apr 2026

stadler said:
• All 373 units are dual voltage but no longer get used on DC. They used to do DC work before HS1 was built.

They still do DC work under 3000V DC catenary in Belgium.

frankmoh · 30 Apr 2026

I don't imagine the 313s assigned to the Watford DC route back in the day used the 25kv capacity very much.

Krystal · 30 Apr 2026

Could one argue that 755 spends most of their days running on diesel, with electric running only happening where they can (and the odd 755 Norwich<->London diagrams)?

LNW-GW Joint · 1 May 2026

frankmoh said:
I don't imagine the 313s assigned to the Watford DC route back in the day used the 25kv capacity very much.

I did once watch a 313 unit move from the DC lines to the main line at Watford, up pantograph and set off south ECS on AC.

Tester · 1 May 2026

frankmoh said:
I don't imagine the 313s assigned to the Watford DC route back in the day used the 25kv capacity very much.

Whilst a small proportion of the total, they used AC regularly as they were based at Hornsey.

And, whilst not regular, the ability to use Euston platforms other than 9/10 was a handy 'get out of trouble' move.

Merle Haggard · 1 May 2026

frankmoh said:
I don't imagine the 313s assigned to the Watford DC route back in the day used the 25kv capacity very much.

In a different world from now - but seemingly (to me) not that long ago , I (and quite a few others) were waiting late at night on the down platform at Leighton Buzzard when a 313 stopped, the doors opened and the driver said he was going to Bletchley and we were welcome to catch it. Presumably ecs to the DED for maintenance.

stadler · 1 May 2026

There was also the 319 which were dual voltage. During their earlier Connex South Central / South Central / Southern / Thameslink / First Capital Connect days they used both voltages. But in their later years at London Midland / London North Western Railway / Northern they solely AC power and their DC capability was no longer used.

tfw756rider · 2 May 2026

Krystal said:
Could one argue that 755 spends most of their days running on diesel, with electric running only happening where they can (and the odd 755 Norwich<->London diagrams)?

And 756s are the opposite, as the discontinuous electrification in the South Wales valleys charges the batteries, and then only if the battery level drops too low does the single diesel engine kick in (I think that's right, would be embarrassing if I got that wrong!)

saismee · 2 May 2026

Krystal said:
Could one argue that 755 spends most of their days running on diesel, with electric running only happening where they can (and the odd 755 Norwich<->London diagrams)?

The 755s run on electric quite frequently actually. Ipswich to Haughley Junction, Ely to Cambridge, Ipswich to Colchester to name three areas where electric is used. It's very important on the GEML to get Cambridge/Peterborough trains out of Stowmarket with the electric acceleration. A lot of the Peterborough services are extended to Colchester in the evenings, and Felixstowe/Lowestoft services rotate their units a lot.

tfw756rider said:
And 756s are the opposite, as the discontinuous electrification in the South Wales valleys charges the batteries, and then only if the battery level drops too low does the single diesel engine kick in (I think that's right, would be embarrassing if I got that wrong!)

Still using multiple modes there, battery and 25KV.

Taunton · 2 May 2026

frankmoh said:
I don't imagine the 313s assigned to the Watford DC route back in the day used the 25kv capacity very much.

When the same sets ran the Richmond to North Woolwich service there was a stage when they did both ends on DC but there were two separate, unconnected 25kV sections in the middle, leading to changing supply four times on each trip.

Brightonboy · 3 May 2026

saismee said:
The 755s run on electric quite frequently actually. Ipswich to Haughley Junction, Ely to Cambridge, Ipswich to Colchester to name three areas where electric is used. It's very important on the GEML to get Cambridge/Peterborough trains out of Stowmarket with the electric acceleration. A lot of the Peterborough services are extended to Colchester in the evenings, and Felixstowe/Lowestoft services rotate their units a lot.

Still using multiple modes there, battery and 25KV.

Presumably the 755s also run on electric Ipswich/Manningtree to Harwich - there is a daily return service Lowestoft-Ipswich-Harwich which, I assume, would swap mode at Ipswich.

saismee · 3 May 2026

Brightonboy said:
Presumably the 755s also run on electric Ipswich/Manningtree to Harwich - there is a daily return service Lowestoft-Ipswich-Harwich which, I assume, would swap mode at Ipswich.

I knew I was forgetting something.

BrianB · 29 Jun 2026

saismee said:
I knew I was forgetting something.

Brightonboy said:
Presumably the 755s also run on electric Ipswich/Manningtree to Harwich - there is a daily return service Lowestoft-Ipswich-Harwich which, I assume, would swap mode at Ipswich.

Does the hourly Norwich - Cambridge/Stanstead service also run on electric south of Ely?

saismee · 29 Jun 2026

BrianB said:
Does the hourly Norwich - Cambridge/Stanstead service also run on electric south of Ely?

Yes.

Some other services will also run on electric around Ipswich occasionally, such as 2R19. It depends on the driver, but they may switch to electric when waiting outside the station, then it shunts on electric to P1.

Islineclear3_1 · 29 Jun 2026

Historical perspective in terms of "have had"

The MLVs on the former Southern Region were equipped for both 3rd rail operation and batteries for shunting around dockyards/unelectrified depot sidings but they ran off 3rd rail most of the time. Similarly, the Class 71s were equipped for both 3rd rail operation and overhead wire collection in depots. They ran off the 3rd rail most of the time. Then there were Class 74s which had a diesel engine for working away from electrified lines, but they ran off 3rd rail most of the time. Class 73 has already been mentioned.

Perhaps these were "bi-modes" of their day

Trivia: Trains that have/had dual mode capabilities but run/ran on one mode most of the time

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