Has the Sheffield Tram Train been a success? Could tram trains work in other places in the UK?

[SouthEastBuses]

This topic is for the discussion of the Karlsruhe model of public transport systems - basically trams and trains all combined into one (tram-train).

We know how successful tram trains have been in Karlsruhe, as shown here: https://www.railway-technology.com/projects/karlsruhe/

The success of the Albtalbahn and Hardtbahn prompted a study into how other communities around Karlsruhe might benefit from similar light rail links into the city.

(the Albtalbahn and Hardtbahn are some of Karlsruhe's tram train lines)

The UK has such system in Sheffield with a Supertram line connecting Sheffield City Centre with Rotherham Parkgate.

Has Sheffield's tram train been successful, and if yes, could tram trains work in other UK cities?

I'm thinking Plymouth is somewhere where costs could be justified such system, with a line from Gunnislake, via the current Tamar Valley Line, to Plymouth Railway Station then street running to the city centre. Another line could be implemented from Plymouth City Centre to Totnes via the existing Plymouth-Exeter railway line, encouraging new stations at large communities that don't have one (e.g. Plympton, South Brent).

The only problem I can think of is that electrification will be required for the Tamar Valley Line and part of the Plymouth-Exeter railway line unless if it would be done like Kassel or Chemnitz with bi-mode trams (electric overhead wires in the city centre and diesel power on the railway lines), or with batteries like in Cardiff.

I am also aware that a new tram train system is being built in Cardiff (South Wales Metro), and that Manchester also is considering building a tram-train system too.

@Bletchleyite I think this topic might be of most interest to you!

 

[Bletchleyite]

The Severn Beach line in Bristol is a fairly obvious candidate.

 

[Dr Day]

Success depends on whether you achieved your objectives when you started out.

I'm not familiar enough with Sheffield to know what these were for the tram-train scheme, but in terms of having proven that something is feasible then clearly it is, but not after a lot of cost and interface hassle both technically and organisationally.

https://www.nao.org.uk/reports/the-...he-modification-of-the-national-rail-network/

I'm not sure Cardiff is really a 'new system' - purely the existing heavy rail Valleys lines being electrified with mainly 25kV and operated by vehicles that also have the potential to operate on-street under battery power, with on-street only envisaged for a short section beyond Cardiff Bay (IIUI).

 

[HSTEd]

A large part of the conversion's cost was caused by the development and validation of a dual purpose 750V/25kV set of electrification equipment. The idea being to save money if someone ever wanted to convert the line to 25kV.

That technology has now been developed, and you could simply not bother with that if you wanted.


As for potential projects, there are loads of options. My personal favourite are the lines around Nottingham, including the Grantham-Nottingham line.

 

[Arkeeos]

Tram Trains have their place, whether or not they were most suitable in Sheffield, I don't think we can ever quite know. I think the fear is that they will be seen as cheap alternatives to regular rail, rather than something that has a specific purpose.

I think the best place to use tram trains would be in Cambridge and have them run to Newmarket, and then up to Ely by reinstating the curve at Newmarket. And that would run onto a greater Cambridge tram network, which we know they are pursuing. That would provide a good commuter route and would spur some development.

Tram could also takeover the Tamar valley line in Plymouth and extend to Tavistock as well, and that could also connect into a greater Plymouth tram network. Although, is it even a tram train if the tram doesn;t actually share tracks with national rail services?

Tram-Trains are best suited for areas that have (or will have) an existing tram network and have a poorly placed central station (Which 90% of british cities do not have, and as such trams trains are not suitable for the vast majority of UK cities, especially Manchester.)

 

[Dr Day]

The rationale for Cardiff vehicles appeared to be ‘we want to extend our heavy rail network so need something that can go on street but can also co-exist with a few pesky current freight trains and other heavy rail stuff at Cardiff Central’. Sheffield was more ‘we want to extend our light rail network so need something that can go on Network Rail infrastructure that can also co-exist with our on-street trams.’ Original Manchester Metrolink was ‘we want to join up two poorly performing life expired bits of heavy rail network with termini at opposite sides of the city but want to operate an independent high frequency service’ so could have ‘pure’ trams rather than need something to cope with the complexity of the greater interface with freight even though technically running on Network Rail (BR) owned track.

Plymouth station is definitely a bit of a trek from the Hoe etc, but the operation of a stopper service for new stations between Plymouth and Totnes on the existing rail corridor would face similar capacity issues whether it was operated by a tram train vehicle or a conventional train (diesel/battery/electric or combination thereof).

 

[Brubulus]

Tram Trains have their place, whether or not they were most suitable in Sheffield, I don't think we can ever quite know. I think the fear is that they will be seen as cheap alternatives to regular rail, rather than something that has a specific purpose.

I think the best place to use tram trains would be in Cambridge and have them run to Newmarket, and then up to Ely by reinstating the curve at Newmarket. And that would run onto a greater Cambridge tram network, which we know they are pursuing. That would provide a good commuter route and would spur some development.

Tram could also takeover the Tamar valley line in Plymouth and extend to Tavistock as well, and that could also connect into a greater Plymouth tram network. Although, is it even a tram train if the tram doesn;t actually share tracks with national rail services?

Tram-Trains are best suited for areas that have (or will have) an existing tram network and have a poorly placed central station.

Tram Trains in Cambridge could work with converting the busways into tram routes and using the railway as a faster route through the centre. This would be very useful for people who live on a diffrent side of Cambridge to where they work, esp as employment is no longer concentrated in the city centre. The main issue is frequency as you've got 4tph to Ely and 1tph to Ipswich plus 2tph Cambridge North terminators. Ipswich could pretty much be treated differently as it branches off halfway through but that leaves 6tph. One of the Cambridge North terminators could be cut back, which allows for 5tph trams, even if there is some irregularities. Leave the Newmarket line as heavy rail, but extend the loop at Dullingham significantly so it can handle 2tph.

 

[Bantamzen]

If the concept ever sees the light of day, tram-trains would probably be necessary to enable a West Yorkshire network. In particular being able to use sections along the Leeds-Bradford-Low Moor & Bradford-Guiseley sections which are part of the aspiration to provide a tram network between the two cities & the airport, as well as towards the Spen Valley.

 

[tbtc]

Success depends on whether you achieved your objectives when you started out

That’s the important point

Some people seem to treat the fact that a line was reopened as evidence that it was a “success” regardless of costs/ passenger numbers/ time frames etc

If the Sheffield scheme was to be assessed in terms of being delivered on time and on budget then it’s been a failure, it seems much more complicated than had been initial assumed. Whilst most other light rail systems in the UK have been able to “conventionally” extend their networks without too much complication, Sheffield got stuck in a deal where the government would only help fund expansion if we agreed to be the guinea pigs for experimental technology (in UK terms at least).

If the Sheffield scheme is being assessed in terms of opening up new areas/ regeneration etc then it’s probably a failure. There’s only one new station, the single platform Parkgate (given that Rotherham Central was an existing heavy rail station and money hasn’t been found for a new station at Magna)

If the Sheffield scheme is assessed as meeting huge local demand then it’s probably a bit of a failure. There are a lot of other routes where Supertram could have been expanded without the expensive complications of Tram Trains (e.g. beyond Herdings Park to a P&R at Meadowhead, expansion to the Hallamshire/ Northern General, the proposed route via Flat Street etc to push the Ring Road up onto the embankment currently used by trams…)

If the Sheffield scheme is assessed in terms of simplicity then… it’s a bit if a mess, three trams an hour but with ten/ twenty/ thirty minute gaps due to the lopsided Northern Rail times through Rotherham… so there’s a combined service roughly every ten minutes but badly split so that two trams run then two trains… But that’s the only real way to fit in between the trains

The Sheffield scheme

But if the Sheffield scheme is being assessed in terms of keeping Rotherham’s rail service going then it’s been a huge success, given that the long established half hourly Northern Rail service from Doncaster to Sheffield has dropped down to every ninety minutes due to staff shortages/ OLR

If the Sheffield scheme is being assessed in terms of getting additional trams for the conventional network (given that the original fleet is fairly stretched as it stories thirty years of intensive use) then it’s been a success, as the costs of just getting a couple of compatible vehicles might have been eye wateringly high otherwise

Apologies for the general cynicism but my take on it is asking the lines of “it wasn’t a big priority, and we’ve been dumped with an expensive complicated test bed so that lessons can be learned for other cities, but since we aren’t seemingly able to just expand conventional tram routes like Manchester/ Nottingham etc then it was probably worth doing since it was essentially this messy project or nothing”

 

[Iskra]

That’s the important point

Some people seem to treat the fact that a line was reopened as evidence that it was a “success” regardless of costs/ passenger numbers/ time frames etc

If the Sheffield scheme was to be assessed in terms of being delivered on time and on budget then it’s been a failure, it seems much more complicated than had been initial assumed. Whilst most other light rail systems in the UK have been able to “conventionally” extend their networks without too much complication, Sheffield got stuck in a deal where the government would only help fund expansion if we agreed to be the guinea pigs for experimental technology (in UK terms at least).

If the Sheffield scheme is being assessed in terms of opening up new areas/ regeneration etc then it’s probably a failure. There’s only one new station, the single platform Parkgate (given that Rotherham Central was an existing heavy rail station and money hasn’t been found for a new station at Magna)

If the Sheffield scheme is assessed as meeting huge local demand then it’s probably a bit of a failure. There are a lot of other routes where Supertram could have been expanded without the expensive complications of Tram Trains (e.g. beyond Herdings Park to a P&R at Meadowhead, expansion to the Hallamshire/ Northern General, the proposed route via Flat Street etc to push the Ring Road up onto the embankment currently used by trams…)

If the Sheffield scheme is assessed in terms of simplicity then… it’s a bit if a mess, three trams an hour but with ten/ twenty/ thirty minute gaps due to the lopsided Northern Rail times through Rotherham… so there’s a combined service roughly every ten minutes but badly split so that two trams run then two trains… But that’s the only real way to fit in between the trains

The Sheffield scheme

But if the Sheffield scheme is being assessed in terms of keeping Rotherham’s rail service going then it’s been a huge success, given that the long established half hourly Northern Rail service from Doncaster to Sheffield has dropped down to every ninety minutes due to staff shortages/ OLR

If the Sheffield scheme is being assessed in terms of getting additional trams for the conventional network (given that the original fleet is fairly stretched as it stories thirty years of intensive use) then it’s been a success, as the costs of just getting a couple of compatible vehicles might have been eye wateringly high otherwise

Apologies for the general cynicism but my take on it is asking the lines of “it wasn’t a big priority, and we’ve been dumped with an expensive complicated test bed so that lessons can be learned for other cities, but since we aren’t seemingly able to just expand conventional tram routes like Manchester/ Nottingham etc then it was probably worth doing since it was essentially this messy project or nothing”

But, that's actually a big thing for Rotherham. That's where the main economic activity of Rotherham takes place, rather than the town centre. Parkgate has effectively replaced the traditional Town Centre and is incredibly popular, so people being able to get from there to Sheffield is quite important and a tram stop there is very useful. Plus there's the park and ride potential for Rotherham-Sheffield.

 

[tbtc]

But, that's actually a big thing for Rotherham. That's where the main economic activity of Rotherham takes place, rather than the town centre. Parkgate has effectively replaced the traditional Town Centre and is incredibly popular, so people being able to get from there to Sheffield is quite important and a tram stop there is very useful. Plus there's the park and ride potential for Rotherham-Sheffield.

Unfortunately Parkgate don’t seem particularly bothered about their busy car parks being used by lots of people dumping cars there to go work/ socialise/ spend in Sheffield, so the P&R aspect is very token

It’s a shame as a regular service to Sheffield (and Tinsley, which is essentially the back door of Meadowhall, or will be once someone occupies the Debenhams site) plus plenty of dedicated parking would be very useful and remove a lot of journeys from our roads

Due to the way that heavy industry created a lot of separate “pit villages” etc there’s a lot of communities in the Dearne Valley which public transport struggles to serve well, especially given the sutras of demand between Barnsley/ Doncaster/ Parkgate/ Rotherham/ Meadowhall/ Sheffield etc - a “railhead” At Parkgate could unlock this

Instead we have a limited number of parking spaces (for P&R) and half hourly gaps in the frequency which make the tram train a lot less attractive

But the spread of Northern Rail paths (even if they don’t use them all…) means that there’s no scope for the tram to run at a frequent/ balanced timetable… for that to happen we’d need those passenger trains to run the Masbrough route (maybe with trams extending to Swinton to connect to heavy rail there?), but that’d mean no passenger trains in central Rotherham which is generally seen as unacceptable

Meanwhile, Manchester/ Nottingham just get on with building conventional extensions to their light rail, allowing frequent services to penetrate each new branch

 

[Iskra]

Unfortunately Parkgate don’t seem particularly bothered about their busy car parks being used by lots of people dumping cars there to go work/ socialise/ spend in Sheffield, so the P&R aspect is very token

It’s a shame as a regular service to Sheffield (and Tinsley, which is essentially the back door of Meadowhall, or will be once someone occupies the Debenhams site) plus plenty of dedicated parking would be very useful and remove a lot of journeys from our roads

Due to the way that heavy industry created a lot of separate “pit villages” etc there’s a lot of communities in the Dearne Valley which public transport struggles to serve well, especially given the sutras of demand between Barnsley/ Doncaster/ Parkgate/ Rotherham/ Meadowhall/ Sheffield etc - a “railhead” At Parkgate could unlock this

Instead we have a limited number of parking spaces (for P&R) and half hourly gaps in the frequency which make the tram train a lot less attractive

But the spread of Northern Rail paths (even if they don’t use them all…) means that there’s no scope for the tram to run at a frequent/ balanced timetable… for that to happen we’d need those passenger trains to run the Masbrough route (maybe with trams extending to Swinton to connect to heavy rail there?), but that’d mean no passenger trains in central Rotherham which is generally seen as unacceptable

Meanwhile, Manchester/ Nottingham just get on with building conventional extensions to their light rail, allowing frequent services to penetrate each new branch

We should probably be happy that there has been an attempt to acknowledge the reality of the shift of demand from the traditional centre of Rotherham, to the real area where people want to be. We've also seen a genuine attempt to deliver something to cater for that demand in an era where most things get rubbished very easily as 'too difficult' or 'too expensive.' You are right that the P&R aspect is token, but it's a start.

 

[javelin]

The Sheffield tram-train is a pilot. The whole point was to make mistakes now so that future tram-train projects had many of the risks mitigated. Cost overruns were effectively baked in due to it being a learning process, so the usual complaints about cost are a bit misguided. This is especially true given that some of it had nothing to do with the project itself but the faffing around when the government announced electrification through Rotherham only to then drop it again. Hence designing NR-spec wiring for 25kV only to then run DC along it.

A more relevant criticsm is that as a pilot it wasn't effective. For example GM is looking to run its own pilots before using tram-trains. This shouldn't have been deemed necessary if the Sheffield pilot was a comprehensive test of tram-train operation in the first place.

 

[Meerkat]

The Severn Beach line in Bristol is a fairly obvious candidate.

To go where? My crayoning used to roughly follow the old freight line and tunnel from Temple Meads to join the harbour railway alongside the Floating Harbour and join up with the Portishead line, but I think the developments have now blocked access to Temple Meads. Or are you thinking of linking Clifton Down to the centre down the A-road?

Tram Trains in Cambridge could work with converting the busways into tram routes and using the railway as a faster route through the centre.

Can't use just use the busway to Cambridge North then get the train to Cambridge South (eventually)?

 

[willgreen]

money hasn’t been found for a new station at Magna

Minor point - IIRC money has now been found? Agree with the rest of the post though, as a standalone scheme Rotherham wasn't hugely impressive but it's the theoretical technology boost which could be helpful. Sheffield-Doncaster is probably more likely now (starting from a low base admittedly).

 

[Bletchleyite]

To go where? My crayoning used to roughly follow the old freight line and tunnel from Temple Meads to join the harbour railway alongside the Floating Harbour and join up with the Portishead line, but I think the developments have now blocked access to Temple Meads. Or are you thinking of linking Clifton Down to the centre down the A-road?

I hadn't thought it through in depth to be honest, only that the line loops round Bristol in a very useful fashion but then terminates at Temple Meads half an hour's walk from the centre. Some way of connecting that segregated loop to a city centre tramway would be very useful.

Can't use just use the busway to Cambridge North then get the train to Cambridge South (eventually)?

Both Cambridge stations are a similar distance from the centre.

 

[YorksLad12]

If the Sheffield scheme is being assessed in terms of opening up new areas/ regeneration etc then it’s probably a failure. There’s only one new station, the single platform Parkgate (given that Rotherham Central was an existing heavy rail station and money hasn’t been found for a new station at Magna)

Preparatory work on Magna is about to start. A new stop with park & ride should be open in the second half of next year.

If the Sheffield scheme is assessed in terms of simplicity then… it’s a bit if a mess, three trams an hour but with ten/ twenty/ thirty minute gaps due to the lopsided Northern Rail times through Rotherham… so there’s a combined service roughly every ten minutes but badly split so that two trams run then two trains… But that’s the only real way to fit in between the trains

That's down to pathing. Thanks to the pandemic and reduced passenger numbers it's down to two evenly-spaced departures, but the aspiration has always been for three evenly-spaced departures. Changes to heavy rail timetables might yet facilitate this.

Apologies for the general cynicism

It's a Monday, it's allowed.

Unfortunately Parkgate don’t seem particularly bothered about their busy car parks being used by lots of people dumping cars there to go work/ socialise/ spend in Sheffield, so the P&R aspect is very token

A new, dedicated P&R site is coming for Parkgate, linked to the development that's just started off Aldwarke Lane.

But the spread of Northern Rail paths (even if they don’t use them all…) means that there’s no scope for the tram to run at a frequent/ balanced timetable… for that to happen we’d need those passenger trains to run the Masbrough route (maybe with trams extending to Swinton to connect to heavy rail there?), but that’d mean no passenger trains in central Rotherham which is generally seen as unacceptable

There have been murmurings of extending tram train to Mexborough and possibly on to Doncaster, either on the current, shared route north of Rotherham or via the freight line (which would require at least one new stop for Swinton, possibly also Kilnhurst - both had "-Central" stations on that line). Couldn't say how far those murmurings have got. Were I to speculate, you could have every 15 minutes to Rotherham, two terminating at Parkgate, two extending to Doncaster but coming off the track and onto a road terminus outside the station, and removing Northern's heavy rail service. That's just me speculating though. Also, a plan for a Rotherham Mainline station, though I can't work out exactly where.

 

[johnnychips]

Please leave the stopper from Sheffield to Doncaster alone, or indeed restore it to its two-per-hour frequency. At worst it takes 44 minutes; the tram takes 27 minutes just to get from Sheffield to Parkgate.

 

[Iskra]

Please leave the stopper from Sheffield to Doncaster alone, or indeed restore it to its two-per-hour frequency. At worst it takes 44 minutes; the tram takes 27 minutes just to get from Sheffield to Parkgate.

Agreed

 

[JonathanH]

I hadn't thought it through in depth to be honest, only that the line loops round Bristol in a very useful fashion but then terminates at Temple Meads half an hour's walk from the centre.

Half an hour? It is no accident that the commercial activity has been edging closer to Temple Meads in recent times which has increased the relevance of the railway for local use. Using the railway to get from Clifton Down to Temple Meads for Cabot Circus or the Harbourside probably doesn't happen admittedly.

Lawrence Hill is also (just about) within walking distance of the centre of Bristol as well, as is Clifton Down itself, depending on where you want.

A tramway in Bristol wouldn't use the Severn Beach line inside Clifton Down.

 

[Shaw S Hunter]

The trouble with this discussion is that it's based on a false premise, namely that the Rotherham/Meadowhall extension of the South Yorkshire Supertram network uses tram-trains. The electrification of the NR tracks involved is to tram standards: a true tram-train would be using heavy-rail (ie 25kV AC) electrification on the NR tracks. The only sense in which the vehicles are bi-systemic is their ability to cope with both street running tram rails and also the slightly different rails used on NR. And it would appear the forthcoming South Wales Metro vehicles will also not be genuine tram-trains. Some may say I'm quibbling about "engineering semantics" but IMO opinion we will only have genuine tram-trains in this country when they come kitted out with the ability to run both as fully electrified street runners and under 25kV mainline OHLE. As such speculating about where else they could be introduced is somewhat jumping the gun. Let's get the concept genuinely proven to British operating standards first.

 

[edwin_m]

The trouble with this discussion is that it's based on a false premise, namely that the Rotherham/Meadowhall extension of the South Yorkshire Supertram network uses tram-trains. The electrification of the NR tracks involved is to tram standards: a true tram-train would be using heavy-rail (ie 25kV AC) electrification on the NR tracks. The only sense in which the vehicles are bi-systemic is their ability to cope with both street running tram rails and also the slightly different rails used on NR. And it would appear the forthcoming South Wales Metro vehicles will also not be genuine tram-trains. Some may say I'm quibbling about "engineering semantics" but IMO opinion we will only have genuine tram-trains in this country when they come kitted out with the ability to run both as fully electrified street runners and under 25kV mainline OHLE. As such speculating about where else they could be introduced is somewhat jumping the gun. Let's get the concept genuinely proven to British operating standards first.

The Sheffield scheme was designed to allow for the route to be converted to 25kV, which was quite likely to happen at the time though I believe it wasn't one of the routes that was approved and then cancelled. Hence the tram-trains have a 25kV capability, carrying a transformer that isn't used and possibly never will be. The OLE is also designed to be convertable, hence looks more like 25kV equipment than 750V tramway overhead. Interestingly one of the conclusions from the trial was that it would have been better just to install standard tramway overhead and replace it if 25kV was ever needed - though I suspect this is just a case of "the grass is greener on the other side of the fence" and they'd have had just as many approval issues if they'd done that.

 

[Greybeard33]

The Sheffield scheme was designed to allow for the route to be converted to 25kV, which was quite likely to happen at the time though I believe it wasn't one of the routes that was approved and then cancelled. Hence the tram-trains have a 25kV capability, carrying a transformer that isn't used and possibly never will be. The OLE is also designed to be convertable, hence looks more like 25kV equipment than 750V tramway overhead. Interestingly one of the conclusions from the trial was that it would have been better just to install standard tramway overhead and replace it if 25kV was ever needed - though I suspect this is just a case of "the grass is greener on the other side of the fence" and they'd have had just as many approval issues if they'd done that.

Furthermore, tram-trains in other European countries routinely switch between DC tramway and AC mainline OLE. I fail to see what exceptional features of "British operating standards" require a local demonstration of this switchover capability.

The TfW Class 398s are based on the same Stadler Citylink platform as the Sheffield Class 399s, but I believe TfW has opted for the standard heavy rail wheel profile rather than the special hybrid tram-train profile developed for the 399. This avoids the need for fitting raised check rails to all switches and crossings throughout the Core Valley Lines, as was done in Rotherham. However, the TfW units will consequently require grooved rail with a wider and deeper groove than normal tramway rail on any future street running sections. I fear this might prove hazardous to pedestrians and cyclists (risk of tripping/cycle wheels becoming trapped).

 

[Bletchleyite]

Furthermore, tram-trains in other European countries routinely switch between DC tramway and AC mainline OLE. I fail to see what exceptional features of "British operating standards" require a local demonstration of this switchover capability.

The TfW Class 398s are based on the same Stadler Citylink platform as the Sheffield Class 399s, but I believe TfW has opted for the standard heavy rail wheel profile rather than the special hybrid tram-train profile developed for the 399. This avoids the need for fitting raised check rails to all switches and crossings throughout the Core Valley Lines, as was done in Rotherham. However, the TfW units will consequently require grooved rail with a wider and deeper groove than normal tramway rail on any future street running sections. I fear this might prove hazardous to pedestrians and cyclists (risk of tripping/cycle wheels becoming trapped).

How much of an issue that is depends on what street running is proposed. If it's possible to have semi-segregated right of way (as per parts of Blackpool, say, which is definitely a street tramway but has quite long sections with barriers on both sides) then it may not be an actual issue. If Cardiff ends up with a proper street tramway then the decision can presumably be revisited; swapping the wheelsets is likely to be a tiny part of the cost of building a full street tramway network, and in the meantime not having wear and terrible side to side hunting like Metrolink does is a great benefit.

 

[Peterthegreat]

Agreed

Also agreed.

 

[MarkyT]

The Sheffield scheme was designed to allow for the route to be converted to 25kV, which was quite likely to happen at the time though I believe it wasn't one of the routes that was approved and then cancelled. Hence the tram-trains have a 25kV capability, carrying a transformer that isn't used and possibly never will be. The OLE is also designed to be convertable, hence looks more like 25kV equipment than 750V tramway overhead. Interestingly one of the conclusions from the trial was that it would have been better just to install standard tramway overhead and replace it if 25kV was ever needed - though I suspect this is just a case of "the grass is greener on the other side of the fence" and they'd have had just as many approval issues if they'd done that.

A late change no doubt contributing heavily to project completion delay and cost overrun was the reconstruction of the deck of a road overbridge at Rotherham Central station. That it was not done earlier suggests it was only required for the 25kV futureproofing, itself also a late change I believe, and may not have been needed for a simpler trolley wire electrification scheme solely for lower DC voltage. I don't know if there were any other structures affected by this. As with most projects, clearly agreed objectives and specs and avoidance of their change during implementation are key to success.

How much of an issue that is depends on what street running is proposed. If it's possible to have semi-segregated right of way (as per parts of Blackpool, say, which is definitely a street tramway but has quite long sections with barriers on both sides) then it may not be an actual issue. If Cardiff ends up with a proper street tramway then the decision can presumably be revisited; swapping the wheelsets is likely to be a tiny part of the cost of building a full street tramway network, and in the meantime not having wear and terrible side to side hunting like Metrolink does is a great benefit.

Agree with that. If rail/road lane intersections are always at a fairly large angle and there aren't any shared lanes, especially those likely to be used by cycles, then the risks to the public of wider and deeper flange gaps are minimised. In Zwickau, Germany there's a 'train-tram' system employing standard gauge heavy rail diesel units sharing part of an urban street track route with electrified metre gauge city trams. The dual gauge section must have flange gaps to accomodate the mainline trains' wheel profile, although the limited range of dedicated heavy rail stock that uses this section could mean they have a special compromise wheel profile similar to the 'Karlsruhe model' employed in Sheffield.

Zwickau Model - Wikipedia

en.wikipedia.org

 

[dosxuk]

IIRC it was quite late in the day when there was a decision made to use 750V DC tram style OHLE, but it then became clear that Network Rail had no 750V DC standards and that they weren't willing to use the existing tram network operators knowledge to form the basis of their own standards - so faced with another big delay while NR worked out how to erect 750V catenary, it was decided to switch back to using the 25kV standards but only feed them at 750V.

The decision not to use 25kV was down to the issues of getting a grid supply - 750V could be fed off the existing grid supplies in the area relatively cheaply and quickly - but it has all been designed to be able to be switched to 25kV in the event of electrification in the wider area.

 

[MarkyT]

IIRC it was quite late in the day when there was a decision made to use 750V DC tram style OHLE, but it then became clear that Network Rail had no 750V DC standards and that they weren't willing to use the existing tram network operators knowledge to form the basis of their own standards - so faced with another big delay while NR worked out how to erect 750V catenary, it was decided to switch back to using the 25kV standards but only feed them at 750V.

The decision not to use 25kV was down to the issues of getting a grid supply - 750V could be fed off the existing grid supplies in the area relatively cheaply and quickly - but it has all been designed to be able to be switched to 25kV in the event of electrification in the wider area.

As a new technology pilot scheme, Rotherham tram-train was probably always going to be rather risky and subject to some unforeseen changes. Project finance planning should have recognised this and had various levels of contingency funding available for anticipated scenarios. A big lesson learned for any future implementations must be to avoid these kinds of uncertainties.

 

[Greybeard33]

IIRC it was quite late in the day when there was a decision made to use 750V DC tram style OHLE, but it then became clear that Network Rail had no 750V DC standards and that they weren't willing to use the existing tram network operators knowledge to form the basis of their own standards - so faced with another big delay while NR worked out how to erect 750V catenary, it was decided to switch back to using the 25kV standards but only feed them at 750V.

The decision not to use 25kV was down to the issues of getting a grid supply - 750V could be fed off the existing grid supplies in the area relatively cheaply and quickly - but it has all been designed to be able to be switched to 25kV in the event of electrification in the wider area.

Although the OLE is based on 25kV standards, with 25kV main insulators on the cantilevers, it is bespoke in having additional small 750V insulators in the catenary supports and registration arms. These provide compliance with the tramway DC OLE requirement for double insulation from earth.

 

[GingerSte]

Although the OLE is based on 25kV standards, with 25kV main insulators on the cantilevers, it is bespoke in having additional small 750V insulators in the catenary supports and registration arms. These provide compliance with the tramway DC OLE requirement for double insulation from earth.

Would that allow for conversion to 25kv then?

(Forgive me - I don't know too much about the elastic trickery.)