e-mosty September 2018 Vessels and Equipment Used for Bridge Construction | Page 58

Figure 15: ULE was lowering down
Figure 18: Illustrated view of Underwater Levelling Frame (ULE)
CAISSON CONSTRUCTION
Caisson construction was completed in two main stages:
1) dry dock and 2) wet dock as explained in following
sections.
Dry Dock Caisson Construction
After completing partial construction of the caissons in
the dry dock, preparations for floating and towing to the
wet dock were performed by installing winches, roller
chain stoppers specially designed by STFA-Gürdesan, tow
plates designed by SMIT, and finally large Yokohama
pneumatic fenders, which were critical components for
these marine (initial launching) works.
Caisson Towing and submerging
Initial and final launching and submerging of the caissons
was executed under the close supervision and design of
the SMIT (of Boskalis), who was a nominated
subcontractor of STFA Construction Co. from the tender
stage.
Initial Launching
The caissons were first towed out from the dry dock
through the approach channel and moored to the
designated location in the wet dock) approx. 5 NM
(9.26Km) from the dry dock.
Figure 19: Towing of caissons from dry dock to wet dock
Figures 16 and 17: Caisson construction at dry dock
3/2018