Nick H (UK) wrote:
Dr. Sunil wrote:

As part of Transport for London's (TfL's) commitment to improve
conditions on the London road network, TfL is currently carrying out
a £15.5 million refurbishment to extend the life of the southbound
Blackwall tunnel by 30 years.

That suggests it would die/close/collapse if they didn't do the work, but
it's only 36 years old!

snip

Why don't they put north- and south-bound traffic through the same
tunnel as has been done in the past? Any ideas?

It's been many years since there was two-way traffic in the old tunnel (as
there was of course for the first 70 years of its existence). IIRC it
originally had a footway on each side like Rotherhithe tunnel. After the
new tunnel was opened in 1967, they widened the carriageway of the old
tunnel by removing the right-hand footway. The right-hand lane, being
close to the tunnel wall, has a very restricted maximum vehicle height,
which means that it cannot be used as the sole southbound lane. Hence it
is not possible to run two-way traffic through the old tunnel.

--
Richard J.
(to e-mail me, swap uk and yon in address)