Thameslink Core OHLE and Third Rail operations 2012

[heart-of-wessex]

Hello all,

Just trying to add realism to the Thameslink train sim route, set in the year 2012, I can't remember but does the operation from 3rd Rail to OHLE (Northbound) and OHLE to 3rd Rail (Southbound) take place at City Thameslink or was it still at Farringdon? The simulated route has both OHLE and 3rd Rail between City Thameslink and Farringdon which I believe was the case, but I remember going on FCC units on a Sunday when the station was closed and would still stop at City Thameslink to change power, but I can't remember what year that was, but I have a hunch they changed at City Thameslink in 2012 but need confirmation!

Any help appreciated!

 

[swt_passenger]

It now normally happens at Farringdon southbound, and City Thameslink northbound. Before the extension it was Farringdon both ways. I’m not sure OHLE was live at City in 2012.

...there were some “heated” discussions about this back in 2012, around May and a June people were still talking about City T/L wires being permanently earthed and not usable. There’s probably a member who knows exactly what date the new routines became standard practice.

Aah, I’ve found a short thread about it, changeover at City T/L apparently started with the Dec 2013 timetable change according to this:

Thameslink AC/DC changeover.

I have travelled from London Bridge to St Pancras many times and the changeover has always been at Farringdon. However yesterday a northbound 8 car 377 did the swap at City Thameslink. This was about 15:30. Was there a particular reason for this or is it something that happens every now and...

www.railforums.co.uk

 

[heart-of-wessex]

It now normally happens at Farringdon southbound, and City Thameslink northbound. Before the extension it was Farringdon both ways. I’m not sure OHLE was live at City in 2012.

...there were some “heated” discussions about this back in 2012, around May and a June people were still talking about City T/L wires being permanently earthed and not usable. There’s probably a member who knows exactly what date the new routines became standard practice.

Aah, I’ve found a short thread about it, changeover at City T/L apparently started with the Dec 2013 timetable change according to this:

Thameslink AC/DC changeover.

I have travelled from London Bridge to St Pancras many times and the changeover has always been at Farringdon. However yesterday a northbound 8 car 377 did the swap at City Thameslink. This was about 15:30. Was there a particular reason for this or is it something that happens every now and...

www.railforums.co.uk

Ahh so would have still been Farringdon on both ways in 2012, thank you very much for the information and the link, it's most appreciated thank you!

 

[swt_passenger]

Ahh so would have still been Farringdon on both ways in 2012, thank you very much for the information and the link, it's most appreciated thank you!

Thanks to you for saying so...

 

[Taunton]

Interesting that much of the effort seems to have been handling what happened if the changeover didn't work, its unreliability being a key issue (as I believe it was on the GN at Drayton Park as well).

I always thought it should have been done somewhere with some room, either up at Kentish Town or down at Blackfriars, but doing so at Farringdon, already wired to there, and thence doing DC on to the Southern network, was doubtless the cheapest approach. And Thameslink was driven by being just about affordable, on the margins. Did they initially get away without building any substation at all?

 

[Bald Rick]

Interesting that much of the effort seems to have been handling what happened if the changeover didn't work, its unreliability being a key issue (as I believe it was on the GN at Drayton Park as well).

I always thought it should have been done somewhere with some room, either up at Kentish Town or down at Blackfriars, but doing so at Farringdon, already wired to there, and thence doing DC on to the Southern network, was doubtless the cheapest approach. And Thameslink was driven by being just about affordable, on the margins. Did they initially get away without building any substation at all?

It was always done to minimise the issue of interference between systems, and Farringdon / City is the best place for that. Also it needs to be some where where trains stop. And finally you want the AC as far south as possible for the power and thus acceleration. Unfortunately any further south than City and you risk earthing the whole of the inner Southern region.

What substation are you referring to?

 

[Taunton]

I was actually suspecting that an additional substation was not needed.

Thameslink came shortly after the Camden-Stratford AC electrification, alongside the DC lines, which I understand gave all sorts of AC-DC-track circuit stray current interference, even including down on the Victoria Line signalling at Highbury, so I'm sure "lessons had been learned", as the RAIB is fond of saying.

 

[Bald Rick]

I was actually suspecting that an additional substation was not needed.

Thameslink came shortly after the Camden-Stratford AC electrification, alongside the DC lines, which I understand gave all sorts of AC-DC-track circuit stray current interference, even including down on the Victoria Line signalling at Highbury, so I'm sure "lessons had been learned", as the RAIB is fond of saying.

The NLL was a different prospect - 3 or 4 3 car trains a hour, and limited on D.C. on the dual section. Rather different to the frequency and length of trains in the Thameslink core, even in 1989.

 

[Taunton]

The NLL was a different prospect - 3 or 4 3 car trains a hour, and limited on D.C. on the dual section. Rather different to the frequency and length of trains in the Thameslink core, even in 1989.

Was it the DC though - there had always been DC upper level at Highbury (long before the Victoria Line was even built), the stray currents issues arose in the 1980s when AC was put in for the freight services.

 

[Bald Rick]

Was it the DC though - there had always been DC upper level at Highbury (long before the Victoria Line was even built), the stray currents issues arose in the 1980s when AC was put in for the freight services.

It is the combination of the AC and D.C. on the same (or connected) tracks that is the biggest issue, but on dual voltage sections it is the D.C. return current that is the difficult bit and ‘strays’.

There’s rarely an issue with D.C. stray currents on the 4th rail systems.