"Paul Scott" wrote:

"Bruce" wrote:

There are plenty of structures of this type (precast segmental
pre-stressed post-tensioned) but I think the Hammersmith flyover was
the first. I don't know of any subsequent structure of this type that
lacks the essential combination of bridge deck waterproofing, proper
drainage, adequate concrete cover to reinforcement/pre-stressing
tendons and grouting of tendon ducts.

So Hammersmith is very much a one-off. That doesn't mean that other
structures don't have problems of their own, but the design and
subsequent operation and maintenance practice related to the
Hammersmith flyover seems to have combined in a way that could only
end in tears.

I bet the DfT (or the Highways Agency) are glad that they they ceded all
the trunk roads within London to the GLA. I'm thinking it must have been
transferred at about the same time that all those random motorways within
London were downgraded?

Yes, when the GLA (and hence TfL) was established in 2000. It formed part of
what was initially called the GLRN (Greater London Road Network),
subsequently renamed the TLRN (Transport for London Road Network).

I doubt it, but it could conceivably have been a responsibility of H&F
council pre-2000, rather than that of the HA. I think it fell under the
auspices of the GLC in years past. Be interesting to know when the
quasi-literal rot started!

Re the downgraded motorways - I've read elsewhere speculation, which seems
to have turned into received wisdom amongst some, that this only happened
because of an oversight with the legislation establishing the powers of the
GLA. I have my doubts about that theory - rather, I can well imagine it
being intentional (the thinking being that the notion of widespread 'urban
motorways' is rather something of the past) - but that's just speculation on
my part.