Queensferry Crossing - Erection
The Queensferry Crossing is currently under construction for
client Transport Scotland by contractor Forth Crossing Bridge Constructors
(FCBC), a consortium of Hochtief Solutions, American Bridge International,
Dragados, and Morrison Construction.
The Main Crossing consists of a new road bridge across
the Forth estuary spanning 2,637.5 m between abut-
ments. It is a cable stayed bridge with three mono-tow-
ers, two main spans of 650 m and approach spans to
the north and south. The single level deck is continuous
from abutment to abutment.
Over the cable stayed length it is a single composite
box girder but for the southern approach viaduct and
the last span at the northern end it splits into twin com-
posite box girders.
DLT is the temporary works designer for three key
elements of the main bridge construction, the Approach
Viaduct North (AVN), the cable stay bridge deck erection
gantries, and deck support falsework at piers S1 and S2.
Deck Erection Gantries
The cable supported composite box deck sections
for the main bridge are pre-assembled at the site and
transported by barge to their respective erection points.
There are 109 sections in total ranging in length from
6.1 m to 16.2 m and weight from 260 tonnes to
780 tonnes. They are lifted approximately 50 m from
the delivery barge to permanent deck level. This is
achieved using 6. temporary deck erection gantries using
strand jack technology for lifting.
The unusual aspect is the need for the gantries to fit
between the 2 planes of stay cables that are only 4 m
apart in the central section of the bridge. This has led
to a very slender structure that needs sophisticated
control systems to limit eccentric loading from the lifting
strand jacks and retractable feet to allow it to advance
Contractors World UK & Ireland Vol 6 No 1
Contractors World UK & Ireland