Temporary works training course study Pack - Book - Page 108
Case Study 1
The Loddon Bridge Disaster, Berkshire, October 1972
The background
The bridge was part of a viaduct
built
by
contractor Marples
Ridgway in Reading, Berkshire,
as
part
of
the A329(M)
motorway, a link road to the M4
motorway to
eastbound
the
and
carriageways
east.
westbound
and
separate on-slip to
westbound
The
a
the
carriageway
were
all
constructed
on
separate post-tensioned
reinforced
concrete viaduct structures. The westbound viaduct had been completed early in 1972.
The eastbound viaduct consisted of 13 spans
between reinforced concrete piers. The span over
the River
Loddon,
which
was
the
one
that
collapsed, measured 93 feet (28 m) between piers
35 feet 6 inches (10.82 m) wide. The deck was 4
feet (1.2 m) thick in the centre, tapering at the
outer edges, with an average depth of 1 foot
(0.30 m). It was skew in plan, by around 37
degrees from the angle of the pier, and had a
1:29.25 crossfall built in.
The deck was formed from in-situ concrete laid
onto timber plank formwork which was supported
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