The River Great Ouse
Viaduct with the East
Coast Mainline bridge
in the background
Elements forming
the River Great Ouse
Viaduct
NSC 25
July/Aug 18
all construction work had to take place when
no services were running, and all work had
to be programmed in close partnership with
Network Rail.”
The bridge comprised five pairs of
40m-long girders, with each pair weighing
85t.
Initially the girders were due to be
installed over five weekends. However,
Cleveland Bridge says it was able to complete
the work in just three weekends, within the
2am to 6am possession windows.
There was no room for error since
any delay could have seriously disrupted
rail services for thousands of passengers.
Cleveland Bridge says it planned all works
in meticulous detail to ensure that the steel
girders were positioned well before the end
of each possession window.
“This bridge was an exception and would
have been built with steel even if it was less
than 40m-long,” explains Mr McNicholas.
“Only by using steelwork with a slim profile
could we achieve the required headroom for
the railway, while keeping the road at the
necessary level.”
The project’s longest bridge structure is
the 750m-long River Great Ouse viaduct,
which is considered to be a showpiece
element of the A14 project. The bridge not
only spans the river, but also a large area
of floodplain on either side. This viaduct
will require 6,000t of steel, comprising 76
separate main girders and 800 cross girders.
A time-saving construction method
has been devised, which involves another
subcontractor lifting prefabricated concrete
slabs onto the steelwork erected by Cleveland
Bridge at the same time as steelwork
installation continues ahead of this activity.
A key feature of this method are the
close tolerances required between the
deck slabs and supporting steelwork. This
requires precise steelwork fabrication and
installation to ensure clashes between the
slabs, projecting reinforcement and the steel
are avoided.
Supported on 16 pairs of piers, most of
the main girders required for the bridge are
up to 40m-long, 2m-deep and weigh 50t. The
section of bridge that crosses the river has a
longer 70m span, requiring more complex
girders, with larger, deeper haunches to carry
the greater load.
Cleveland Bridge says it suggested a
different steel grade for these haunch girders,
making them simpler to fabricate.
Cleveland Bridge is using a 600t-capacity
crawler crane, which can lift all components
for each bay from one position on both sides
the river. This meant fewer crane movements
were required, with no need to move the
crane across the bridge footprint – reducing
site congestion and saving time and money.
The A14 improvement scheme is due to
be completed in 2021.
Bridges
Three more bridges
Cleveland Bridge is also fabricating and
supplying three further bridges for the
A14 scheme. These consist of the BN20
and BN21 Bar Hill Junction bridges and
the BN27 structure, which is also known as the A14/
A1 link overbridge.
The Bar Hill Junction consists of two identical
47.5m-long bridges, that will be constructed from six
main girders each weighing 55t.
These two bridges are scheduled to be
assembled on site, while being supported on
trestles, before being manoeuvred into their final
positions by Self-Propelled Mobile Transporters
(SPMTs) over two successive weekends in
September.
Measuring 102.5m-long, BN27 will be last of
Cleveland Bridge’s six bridges to be erected in early
2019. Curved in plan and elevation, the bridge will
consist of nine pairs of girders measuring 29m, 34m
and 39.5m long.
/Ladder_deck_composite_bridges#Cross_girders
/Accuracy_of_steel_fabrication#Fabrication_tolerances
/Design_for_steel_bridge_construction#Fabricating_the_steelwork
/Ladder_deck_composite_bridges#Main_girders
/Design_for_steel_bridge_construction#Erection_using_cranes
/Design_for_steel_bridge_construction#Specialist_transport