On Dec 22, 5:15*pm, Tom Page wrote:
Bear in mind also that the existing stations (except Canada Water,
which is of recent construction) will require to be upgraded to be DDA
compliant, which at Shadwell, Wapping and Rotherhithe, for example,
will require new lifts and cross-passageways. (Surrey Quays is a
surface station in a cutting, but this will probably require lifts as
there is little space for ramps.) I also suspect that the narrow
platforms at Wapping will have to be widened, which will involve
widening the tunnel - a major civil engineering task in its own right.
In addition, platforms will require to be lengthend, which at
Rotherhithe and Wapping will require opening out the tunnels (the new
class 378s will, I presume, be 20m vehicles whereas the A stock is
noticeably shorter).

Are lifts going in at these stations as you indicate? I was not aware
of such a plan. I also wasn't aware of any widening work, although
again I may be wrong.

Tom

It is a legal requirement that new works and any sort of upgrade must
be DDA compliant (hence, for example, the tendency not to "refurbish"
rolling stock, which would require DDA compliance, but to "refresh"),
so something will have to be done to make the stations DDA compliant,
which with the exception of New Cross and Canada Water, they are
presently not. And Wapping, in particular, is very, very cramped, so
it would be very difficult to carry out these sorts of works and
maintain access to the station.

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.