Woodhead Third Rail?

[kermit]

Here's a quote from the excellent Disused Stations website;

"When electrification of the line was planned the twin-bore Woodhead tunnels were too narrow and low to allow for the overhead electric cables. Rather than enlarge these tunnels, it was decided to create a new tunnel, immediately to the south of the old ones; this was opened in 1953."

Anyone know why a third rail system was not adopted for the tunnels? Much cheaper to fit the Tommies with shoe gear - a centre third rail for the tunnel portion would not have needed any extra space? OHLE had obvious advantages for the extensive and complex sidings either side of the pennines - but a dual system would have been feasible?

 

[John Webb]

It may be that this was a partial excuse to boost the building of the larger tunnel to improve the gauge available for the more modern rolling stock that then existed compared to that which existed in the 1840s when the original tunnels were built.
It is possible too that the technology available when electrification was being considered pre-WW2 was not sufficient to allow dual systems of current collection to be part of the equation.

 

[Cowley]

It may be that this was a partial excuse to boost the building of the larger tunnel to improve the gauge available for the more modern rolling stock that then existed compared to that which existed in the 1840s when the original tunnels were built.
It is possible too that the technology available when electrification was being considered pre-WW2 was not sufficient to allow dual systems of current collection to be part of the equation.

Either that or they're kicking themselves now and saying "Why didn't we think of that"!?

 

[Ash Bridge]

Would the harsh Pennine winter climate have caused problems for a 3rd rail DC system?

 

[kermit]

Would the harsh Pennine winter climate have caused problems for a 3rd rail DC system?

Not inside a tunnel, surely!

 

[billh]

The old tunnels were falling to bits anyway , caused by continuous exhaust blast from steam locos. Also there was a lot of water entering the tunnels which would not have mixed well with third rail. I don't think a 1500v (as per overhead) 3rd rail system would have been at all practical and switching down to 750v would have limited the power available to the locos too much. CEGB or National Grid had to spend a lot of money repairing one of the old tunnels just to make it suitable to run high voltage cables through.They did install a two foot gauge railway as well.
Bill

 

[kermit]

I don't think a 1500v (as per overhead) 3rd rail system would have been at all practical and switching down to 750v would have limited the power available to the locos too much.
Bill

Class 76, OHLE, 1500v DC, 1300hp.

Class 71, 3rd rail 660 - 750v DC, 2300hp.

If the old tunnels had been repaired, and third railed, further damage from exhaust blast would no longer be an issue.

 

[Greybeard33]

I don't think a 1500v (as per overhead) 3rd rail system would have been at all practical and switching down to 750v would have limited the power available to the locos too much.

The Manchester Victoria to Bury line was electrified at 1200V DC third rail, side contact, from 1916 to 1991. https://en.wikipedia.org/wiki/British_Rail_Class_504

Not much difference between 1200V and 1500V, practicality-wise.

 

[edwin_m]

Class 76, OHLE, 1500v DC, 1300hp.

Class 71, 3rd rail 660 - 750v DC, 2300hp.

Class 76 frequently ran in multiple.

 

[AM9]

Class 76, OHLE, 1500v DC, 1300hp.

Class 71, 3rd rail 660 - 750v DC, 2300hp.

There's a slight difference between a long (unfitted) freight train slogging up to the Woodhead portals with a low voltage supply that really sags under load compared to a heavy boat train on relatively flat tracks picking-up speed.

 

[lightning76]

The old tunnels were falling to bits anyway

Specifically, according to the excellent "The Age of the Electric Train" by JC Gillham (Ian Allan, 1987),

"...the mortar in the joints of the stone lining of the two Woodhead tunnels had badly deteriorated... it was decided to close them permanently and build a new double track tunnel alongside, with enough clearance for overhead catenary."

Apparently electrification plans had existed for some time, suggesting that either modifications to the old tunnels or some other current collection system would have been required, but this was rendered unnecessary due to the decision made to build a new tunnel, as described.

 

[Bevan Price]

l Believe that the Woodhead electrification (and the London Liverpool Street - Shenfield scheme) were considered in part as "test beds" for possible future LNER main line electrification schemes. However, WW2, and then the formation of BR in 1948 put a stop to further electrification schemes (and delayed completion of the Woodhead electrification scheme by about 10 years)

 

[billh]

Class 76, OHLE, 1500v DC, 1300hp.

Class 71, 3rd rail 660 - 750v DC, 2300hp.

.

The 76s one hour rating was over 1800hp and they would have been using all of that in the tunnel. At 750v , assuming there was a means of switching the motors, the current would be double that from the 1500v overhead. If double heading then four times the number of amps for a single loco on the overhead. The 3rd rail would be glowing in the dark.

eta, there was a signal box inside one of the old tunnels for a short while, also regular inspections by Pway staff- I'm not sure I'd be happy wandering around in the dark with a wet floor and high voltages. As it was, corrosion of rails was also a problem , their replacement was required every 3 years, with DC voltages around electrolytic action would destroy rails even quicker.

 

[Cowley]

Maybe not such a good idea then.

 

[kermit]

Maybe not such a good idea then.

I expect they knew what they were doing. Would be interesting to know if they considered and discarded the idea though. Did I ever mention my idea to create DEMUs from ex LU stock with Ford diesel engines?

 

[Cowley]

I expect they knew what they were doing. Would be interesting to know if they considered and discarded the idea though. Did I ever mention my idea to create DEMUs from ex LU stock with Ford diesel engines?

Just spat my tea at the screen!

 

[kermit]

Just spat my tea at the screen!

Sorry!

 

[edwin_m]

I expect they knew what they were doing. Would be interesting to know if they considered and discarded the idea though. Did I ever mention my idea to create DEMUs from ex LU stock with Ford diesel engines?

It may well have been considered. There would have been people around at the time who remembered the NER's proposal to electrify York to Newcastle at 1500V with a mixture of overhead and third rail.

https://books.google.co.uk/books?id...trification york newcastle third rail&f=false

 

[Greybeard33]

As it was, corrosion of rails was also a problem , their replacement was required every 3 years, with DC voltages around electrolytic action would destroy rails even quicker.

There were DC voltages around - that would be what caused the electrolytic corrosion of the rails.

For both DC OLE and DC third rail, the DC return is through the running rails.

Edit: I have since realised that you were probably referring to rail corrosion in the old tunnels, rather than the new one as I assumed above. Sulphur dioxide emitted from the steam engines would have dissolved in the groundwater in the old tunnels to create highly corrosive sulphuric acid. Maybe a switch to electric traction would have reduced rail corrosion despite the electrolytic effects?

 

[randyrippley]

according to http://www.forgottenrelics.co.uk/tunnels/woodhead.html the old tunnel linings were knackered - presumably there had been no attention or maintenance during WWII and a new bore was cheaper in the long run. To quote the site

"Conditions aside, there was no denying Woodhead’s success. An average of 80 trains daily - the majority of them carrying coal westwards or empties back to Yorkshire - made the journey through the hill. But their impact on the tunnels’ lining was severe, eroding the mortar holding it together. The route’s electrification had been given the green light in 1936 and, once hostilities with Germany had come to an end, a substantial programme of renovations was initiated, conducted within overnight and weekend possessions. The decline though proved too great. In 1946, the civil engineering department was granted nine-month occupations of each bore in turn - single line working was instituted through the other tunnel whilst some traffic was diverted via alternative routes. Even then, when these periods were over, it was realised that a more radical solution would have to be implemented to avoid a repeat of the exercise."

 

[contrex]

Not much difference between 1200V and 1500V, practicality-wise.

The PLM electrified Modane - Chambéry at 1500 V third rail in 1925. It remained during SNCF days until 1975 when the line was converted to overhead. The side-contact juice rail was completely encased in wooden shielding except for a narrow slot for the shoe. From 1958 a 3 loco subclass of CC 7100 (CC 7124, 7125 and 7138) were equipped with shoes as well as pantos. From 1969-76 a subclass of CC 6500 (CC 6539 to 6559) were used also.

 

[kermit]

The PLM electrified Modane - Chambéry at 1500 V third rail in 1925. It remained during SNCF days until 1975 when the line was converted to overhead. The side-contact juice rail was completely encased in wooden shielding except for a narrow slot for the shoe. From 1958 a 3 loco subclass of CC 7100 (CC 7124, 7125 and 7138) were equipped with shoes as well as pantos. From 1969-76 a subclass of CC 6500 (CC 6539 to 6559) were used also.

Thank you - very interesting! Essentially then, my idea wasn't completely stupid, but the condition of the old tunnels precluded the option of shoegear on the Tommies as a solution to the problem of clearance. Query thoroughly answered, thanks for your contributions everybody!