London Banter - View Single Post - The East London Line is dead... Long live the East London Line

Tom Anderson · December 23rd 07, 04:12 PM posted to uk.transport.london,uk.railway

On Sat, 22 Dec 2007, wrote:

On the subject of the power supplies, and in particular the conversion
to 3rd rail, since the conversion of the New Line and NLL in the 1970s,
the legal situation has changed considerably. The use of the running
rails for traction return does lead to stray currents, which can and do
corrode anything metallic, especially in damp areas like tunnels. Under
the EMC (Electro-magnetic compatibility) regulations 1992, the railway
must demonstrate that following the conversion, the EM emissions from it
are no greater than those pertaining at present. This will probably
require the installation of additional conductors in parallel with the
running rails in order to reduce the resistance of the return circuit
(cf Farringdon, where an additional "fourth" rail is laid in the
four-foot and bonded to the running rails for this purpose) and to
"encourage" the return currents to flow via the rails and not via earth.
This can also be achieved by the replacement of jointed bullhead rail
(which is largely still used on the ELL) with CWR using heavier flat
bottom rail, which will have a significantly lower resistance in its own
right.

Or by soldering on some cables and laying them alongside the track. Why is
this going to take so long?

tom

--
Ten years on, and there is still nothing like this bizarre tale of
biomechanical space madness.