Challenging Tail Bridge Lifts Made From Barges - continued
Sarens’ Sarspin device – with its four hydraulic levelling cylinders and up to 600-tonne capacity – would also be integral in helping the CC 3800-1 crane to position the pivoting bridge segments.
To handle the 230- and 280-tonne weight of the two bridge segments, required the Demag 650-tonne crane to be configured with its Superlift structure to increase crane capacity.
Accommodating the 11.4-m (37.4-ft) canal width in some areas and crane positioning on the floating base had its own challenges.
We had to install the crane on one barge and the Superlift tray with counterweight on the other,
explains van Oss and adds,
The crane’s tracks were to be positioned perpendicular to the length of the barge, so its 11.3-m (37.1-ft) track tip-to-tip length narrowly passed through the channel.
The massive 30.7-m (100.7-ft) long bridge segments required LSL_2 configuration with 60 m (197 ft) of main boom for the CC 3800-1 crane and 36m Superlift mast, 65 t counterweight on the crane’s superstructure, 50 t central ballast and 325 t on Superlift tray were necessary to give the crane a 347-tonne capacity when working at the predetermined fixed 24-m (78.7-ft) radius.
In early July of 2016, Sarens’ crew members were able to put all of those preparations in action.
The CC 3800-1 was shipped directly from the Zweibrücken (Germany) plant to the mobilization site in Dordrecht.
Sarens’ 10-person crew had the crane rigged with main boom, Superlift mast and full counterweight within three days. The car body was manoeuvred onto the first barge, while the Superlift tray and maximum counterweight was positioned on the second.
Both barges navigated the narrow channel passageway independently of each other.
Once reaching the Queen Maxima Bridge destination, Sarens’ crew members connected the two barges together and the Superlift counterweight tray to the crane.
While a tugboat positioned the two barges carrying the lifting equipment, a separate vessel positioned the enormous balance trap type tail bridge main segment, upended on its wings, next to the crane barge.
Crew members chose to position the west side bridge traffic lanes first. They used ballasting on the crane barge to slowly hoist the tail bridge segment and transfer weight from the transport barge.
The bridge’s eccentric center of gravity challenged our work crew, but they used our Sarspin device to flip and rotate the bridge segment into its final position for connection to the rest of the bridge,
says van Oss.
When you work on water, you have a number of challenges to face – wind, weather, waves and weight transfer – and we faced it all on this job.
It took just short of four hours to lift the west side bridge segment to height and another two hours for moving the crane barges and load into installation position. Within a final three hours, Sarens’ crew attached the pivoting segment of the bridge to complete the first lift. The entire process was completed in one long day.
The two crane equipment barges were then split apart and repositioned on the east side of the Queen Maxima Bridge. Attachment of the second moveable bridge segment went as smoothly as the first. Within two weeks, segment installation was complete and Sarens mobilized the barges with lifting equipment back to Dordrecht for derigging, leaving no sign that they were ever there.