On Mon, 6 Apr 2009, John Rowland wrote:

Tom Anderson wrote:

Plus, something that hasn't been mentioned, i think, is that the
Canonbury curve is single-track - the tunnel there isn't high enough to
take two full-height freight trains, so it was converted from two
tracks to one in the middle (where the arch is highest) when it became
an important freight link.

I was told by an engineer on the ELL project that the Canonbury Curve
was single tracked at electrification because the curved sides of the
tunnel roof were too low for catenary, not too low for freight trains.

I stand corrected. I suppose if you were going to run the ELL up it, you
could (would have to?) make it third-rail, so that would stop being a
problem. Not sure how you maintain the OHLE for freight trains, though,
unless you adopt Theo's idea of gauntletted track ...

tom

--
Argumentative and pedantic, oh, yes. Although it's properly called "correct" -- Huge