Great Western Coffee Shop

From the  BBC (http://www.bbc.co.uk/news/uk-england-london-25576100)

Seems this is only unusual in that someone managed to get a photo into the paper.   

Discussions elsewhere suggest it has happened many times in the past, both on T/L and on a variety of routes with AC/DC changeover, such as the WLL on the way to Shepherds Bush and on the Northern City line at Drayton Park.   

In this particular case there are now some reports that this may have been the pan on the second unit of two, and almost certainly a train fault rather than an error.

At least the BBC haven't actually headlined it as a 'train crash', although they have used the word in the text...

Paul

I was Duty Manager at Reading a few years ago when a container train passing through the old platform 9 at speed hit the canopy, sending bits of wood flying all over the place. Fortunately, no one was hurt. Turned out that a few containers were out of gauge (they had been loaded on the wrong wagons) and, with the help of a slight dip in the track just ahead of the platform, had bounced up enough to take out a hundred yards of facia boards.

Didn't make the news, though!

Indeed. This kind of event with pantographs happens a few times a year across the network.

Pantographs have a thing known as the ADD (automatic dropping device). Pantographs are kept raised using the train's air supply. There are carbon rods inside the hinge of the pantograph. When there are no wires the pantograph fully raises because of the air pressure and breaks the carbon rods causing an air leak and for it to collapse.

In this case the ADD can't operate because the pantograph doesn't appear to have had the chance to fully raise.

It's not much of a big deal in the scheme of things (although a new pantograph costs around ^25k).

The are between Blackfriars Stn and Farringdon St is the "Dual Electrified Area" both 750V dc and 25kV ac systems over the same bit of railway, it has a very complex (unique in the UK possibly in the world) dc / ac buffering system which uses contactors operated by track circuits to switch sections of the 750V third rail on and off as the train moves through the area.

The change over between ac and dc used to take place at Farringdon Stn until a few years ago when the new buffering system became operational, which is still the case for South bound trains (North bound is usually done at City Thameslink Stn) with the changes to the buffering system the OLE was extended South through City Thameslink  it protrudes just out of the North Portal of Snow Hill Tunnel.  Therefore if a driver forgets to lower their Pan or there is a failure in the Pan system it will quite happily run to the North of City Thameslink Stn where the Pan will rise up, the ADD may not have time to fully lower the Pan before it gets into Blackfriars Stn.

Its not the first time this has happened and there are lot of signs fitted to remind drivers.

I think a couple of your 'norths' should be 'souths' ET?   Assuming the south portal of Snow Hill tunnel is now beyond the south end of City Thameslink station, i.e. the original tunnel had the station added to it when it was built?

Yep you are right got my North mixed up with the south for Snow Hill the OLE terminates at the Apothecary Street

A note on the changeover point. Although the OHLE has been commissioned through to City Thameslink for a while now Northbound trains only routinely started changing power supply at City Thameslink with the December 2013 timetable change.