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Tram-Trains for Sheffield to Rotherham


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It's "Fill your boots Monday", with two trams in action, 399202 and 399204 for those that care about these things...

 

From the far end of the line,

Parkgate:

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Rotherham Road:

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Rotherham Central station:

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Ickles, where the Old Road crosses in the background (also showing the electrical supply installation, right, and the newish biomass power station, left background):

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One of the trams (not shown here) had "Rotherham Parkgate TT" in the destination (with TT as the "route code"), but most had "Not in Service" or "Special"

Edited by eastwestdivide
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And It's "More of the same Tuesday", again two trams out.

 

One from beside the level crossing next to Booths scrapyard, showing the New York football stadium in the background. The line in the foreground is the Holmes Chord linking Rotherham Central to Meadowhall. The tram is on the original GC line:

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And two shots from the Bessemer Way bridge/Magna, looking towards Sheffield:

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With a bit of luck I might be able to get down to the Tinsley area some time this week. Back to work for now.

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And the chance of 25kVA arriving via the MML in the next 36 years is probably zero as well.

25kV (not kVA) will arrive in Sheffield as part of HS2 and probably continue through via Meadowhall so Sheffield-Leeds trains can use HS2 for part of their journeys via a northern connection.  So I think the chances of 25kV appearing in the 30ish-year lifetime of the tram-trains and the infrastructure are quite significant - after all who was to say in 2008 that the policy on electrification would reverse twice within the next decade? 

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Carrying out my threat, here are some photos from the Tinsley end of things from today, with 203 and 204 on duty.

From the Rotherham end...

View from Halfpenny Bridge showing the River Don and Tinsley viaduct:

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Tinsley N Junction is the new one where the trams peel off from the existing freight line, here taken from the lower deck of the Tinsley viaduct:

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The connecting chord on the Network Rail side:

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And the tram side:

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Also some engineering shots from today.

 

Roof detail of centre car of one of the new trams:

post-6971-0-44354600-1533135148.jpg

 

Edited to add more detailed shot of panto end:

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There was one pole visible with what looks like a double electrical feed to it.

I'd guess this is a boundary between the Supertram supply and the Network Rail supply, part of the future-proofing for potential 25kV operation. There could be another similar one hidden under the viaduct, making a switchable section where the trams would stop and change over. Only a theory - any other ideas?

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And protecting the junction onto the existing tram network was this signal, including an "end of GSM-R" sign:

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All the trams I saw today traversing the new connection paused on the chord before proceeding, even if there was no other traffic preventing their progress. I'd guess this might be to switch on/off different safety systems (such as the GSM on the sign above).

Edited by eastwestdivide
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Any future transition between 750V and 25kV would require a neutral section of a significnat length, so the "double feed" doesn't serve this purpose.  As there doesn't seem to be a substation building adjacent, I'm assuming both cables are connected by a switch at the foot of the pole, which (in conjunction with powering down the substation further towards Rotherham) will allow the 750Vdc on Network Rail to be isolated while it remains live on Supertram. 

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Any future transition between 750V and 25kV would require a neutral section of a significnat length, so the "double feed" doesn't serve this purpose.  As there doesn't seem to be a substation building adjacent, I'm assuming both cables are connected by a switch at the foot of the pole, which (in conjunction with powering down the substation further towards Rotherham) will allow the 750Vdc on Network Rail to be isolated while it remains live on Supertram. 

 

I believe that switchable sections are (or at least have been) used in stations on the continent where different electrification systems meet.

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Any future transition between 750V and 25kV would require a neutral section of a significnat length, so the "double feed" doesn't serve this purpose.  As there doesn't seem to be a substation building adjacent, I'm assuming both cables are connected by a switch at the foot of the pole, which (in conjunction with powering down the substation further towards Rotherham) will allow the 750Vdc on Network Rail to be isolated while it remains live on Supertram. 

Thanks. Yes, I was suggesting there could be another pole like this out of sight below the viaduct (or maybe towards Tinsley N Junction, which would then presumably allow for a switchable section. So going from the Sheffield end, 750V...special pole...switchable section...special pole...25kV ??

 

I'll have a closer look next time I'm down there. I did see a "section break" near the Meadowhall S tram stop, but not sure if I have a detailed photo.

Edit again: 3rd photo in this post shows some form of section break.

Edited by eastwestdivide
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I believe that switchable sections are (or at least have been) used in stations on the continent where different electrification systems meet.

 

 

The capability to switch from the 3kV Italian supply to the 15kV Swiss supply exists at Chiasso on the Swiss/Italian border and traditionally needed a locomotive change. The use of multi-voltage traction will no doubt make this procedure redundant sooner or later.

 

John

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The capability to switch from the 3kV Italian supply to the 15kV Swiss supply exists at Chiasso on the Swiss/Italian border and traditionally needed a locomotive change. The use of multi-voltage traction will no doubt make this procedure redundant sooner or later.

 

John

Tram-trains can switch between AC and DC systems using the same pantograph.  However they need a long neutral section because the absence of volts for a certain period configures the traction equipment to detect the voltage and close the correct breaker rather than just assuming it's still on the voltage it was before.  I'm told feeding AC into the DC circuit or vice versa would cause serious damage. 

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25kV (not kVA) will arrive in Sheffield as part of HS2 and probably continue through via Meadowhall so Sheffield-Leeds trains can use HS2 for part of their journeys via a northern connection. So I think the chances of 25kV appearing in the 30ish-year lifetime of the tram-trains and the infrastructure are quite significant - after all who was to say in 2008 that the policy on electrification would reverse twice within the next decade?

That's why I said MML.

 

Much as I support the building of HS2, I still believe that it, or at least its extensions beyond Birmingham will be cancelled due to a fall in tax revenues over the next 10 years, and I can't see it being "rescued" by a PPI scheme.

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I believe that switchable sections are (or at least have been) used in stations on the continent where different electrification systems meet.

If you mean a section of catenary that csn be switched between low voltage DC and higher voltage AC, then they do exist. There's one such section on the RhB in Pontesrina station to allow either the DC Bernina line units or AC main line traction to use the same stretch of track.
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Tram-trains can switch between AC and DC systems using the same pantograph. However they need a long neutral section because the absence of volts for a certain period configures the traction equipment to detect the voltage and close the correct breaker rather than just assuming it's still on the voltage it was before. I'm told feeding AC into the DC circuit or vice versa would cause serious damage.

Feeding DC into AC is, in IMHO, very unlikely to do any damage to AC circuits. How can it, the only difference between AC and DC electricity is that the polarity of DC is fixed.

 

Feeding AC into DC is different, though. The changing polarity does the damage to solid state electronics as circuits designed for DC use won't have a rectification bridge included on the supply side to protect against a power source at the opposite polarity. Motors with permanent magnets will burn out.

 

Voltages applied to circuits way above their design voltage will damage those circuits even if it's AC to AC, or DC to DC.

 

So a lower voltage DC supply to a high voltage AC loco is very unlikely to cause any harm. But high voltage AC supply to lower voltage DC loco or EMU is bad news. Even if the polarity change doesn't damage it, the much higher voltage will, unless the circuit has been specifically designed to cope with such circumstances.

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Feeding DC into AC is, in IMHO, very unlikely to do any damage to AC circuits. How can it, the only difference between AC and DC electricity is that the polarity of DC is fixed.

 

Feeding AC into DC is different, though. The changing polarity does the damage to solid state electronics as circuits designed for DC use won't have a rectification bridge included on the supply side to protect against a power source at the opposite polarity. Motors with permanent magnets will burn out.

 

Voltages applied to circuits way above their design voltage will damage those circuits even if it's AC to AC, or DC to DC.

 

So a lower voltage DC supply to a high voltage AC loco is very unlikely to cause any harm. But high voltage AC supply to lower voltage DC loco or EMU is bad news. Even if the polarity change doesn't damage it, the much higher voltage will, unless the circuit has been specifically designed to cope with such circumstances.

I had this from someone heavily involved in the tram-train project.  I think it was something to do with the high current possible on the DC system, exceeding the rating of the high voltage AC system which only needs much lower currents because of its voltage.  The low impedance of the transformer to DC may have come into it too. 

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That's why I said MML.

 

Much as I support the building of HS2, I still believe that it, or at least its extensions beyond Birmingham will be cancelled due to a fall in tax revenues over the next 10 years, and I can't see it being "rescued" by a PPI scheme.

The tram-train is a short distance from the MML itself.  However if Sheffield to Swinton is electrified for HS2 then it's not a big stretch to imagine that infill schemes for local services will follow sometime before the tram-trains are scrapped in perhaps 2048, including the loop through Rotherham Central. 

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I had this from someone heavily involved in the tram-train project.  I think it was something to do with the high current possible on the DC system, exceeding the rating of the high voltage AC system which only needs much lower currents because of its voltage.  The low impedance of the transformer to DC may have come into it too. 

If that's your source, then it must be true, and I bow to your better information.

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The tram-train is a short distance from the MML itself.  However if Sheffield to Swinton is electrified for HS2 then it's not a big stretch to imagine that infill schemes for local services will follow sometime before the tram-trains are scrapped in perhaps 2048, including the loop through Rotherham Central. 

That assumes HS2 is continued north from Birmingham. If the politicians ever get round to finding the money for that, self-driving cars may be posing a much more significant challenge to the concept of railways.

 

There was many years ago a proposal to create self-driving vehicles that would automatically keep station much closer to the vehicle in front than would be safe if under manual control, effectively forming uncoupled "trains". The driver would resume control at their desired slip road. This idea has been mentioned in the present debate over self-driving vehicles, but only for lorries, not cars. But once self-driving is widely accepted, it is quite possible to see this becoming a reality for cars also. It has huge potential benefits in reducing journey times and accidents, not to mention the potential to vastly increase the capacity of our motorways in the same way that computer control allows trains to run with a much shorter headway than is possible with traditional block signalling. 

 

If there is even a hint of this materialising, I really can't see politicians putting any more money into long distance rail travel. 

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Here is a link to the Network Rail guide to Overhead Electrification. http://www.bathnes.gov.uk/sites/default/files/sitedocuments/Planning-and-Building-Control/Planning/nr_a_guide_to_overhead_electrification.pdf

 

I assume that when/if the main line through Rotherham is electrified the section from Meadowhall to Parkgate will be permanently at 25Kv. The tram-trains are designed to switch to 25Kv and there will be a neutral section at the change in the overhead line at the new Meadowhall cord. This is to allow the tram-trains to switch between voltages.

 

This type of switching has been used before as the early West Coast electrification had some stations powered at 6250V AC due to low clearances. I believe that E3001 and E3002 caught fire due to  slow switching of the changeover equipment. 

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As well as the remaining work to be completed on the platforms at Parkgate and Rotherham, work has been going on for a few weeks on a safety parapet for the wall that divides the cutting on the Parkgate side of Rotherham Central from the canal towpath.

In this photo from 30 July, they've fitted the light-coloured parapet to most of it, but were still working near the station end (and the towpath is blocked, although they don't tell you in advance!)

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Earlier shots of the same location here and here

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Was on 399 205 this afternoon from Cathedral to Meadowhall Interchange and the auto announcement system was talking garbage. As we approached various stops, the announcement correctly stated that "This is a yellow route service to Meadowhall Interchange", but on several occasions as we arrived at a stop, for example Attercliffe, the system announced, "This is a yellow route service to Attercliffe", much to the amusement of the passengers.

 

John

Edited by JJGraphics
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Even with that parapet it looks quite easy to use that gate as a ladder to climb over the wall, should someone wish to. 

Not only that, but the ground rises up to the right of the gate. Here is where you can stand...

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...for this picture. I wasn't standing or climbing on anything other than the ground, and I'm not 6ft tall:

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It's a long drop to rail level. 

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