Madsen Giersing was appointed by John Holland Group to undertake the detailed design of the Self Launching Jetty Traveller (SLJT) to facilitate construction of the 900m long access jetty at Cape Lambert Port B in Western Australia.
The SLJT supported a Mantowoc 16000 (400T) crawler crane with a 48m boom. An IHC 150S hammer and a Junttan HHK255 hammer were used to drive the jetty piles. The crane on the SLJT was used for the installation of the jetty headstocks, struts and pre-assembled roadways.
The SLJT comprising two large box beams, 1200mm x 2000mm x approximately 60m long was supported on a roller assembly. Each roller assembly comprised 8 x 300mm diameter steel rollers. The roller system had the ability to equalise the load through a central rocker system. The main beams of the structure were pre-cambered to reduce deflections during operation. The main beams were assembled on shore adjacent to the jetty abutment and comprised four different sections.
The SLJT moved longitudinally using a hydraulic launching system. Two rams (each with a stroke of 1m) grabbed the launching beam, which spanned between the headstocks. A further advantage of this system was that the SLJT could be launched either forward or backward at any time. The pile gate system for the SLJT was able to accommodate various configurations of the 1400mm diameter piles used on the access jetty. This system was able to drive piles for two and three pile bents including vertical and raked (1:4) piles. All gates were operated using a hydraulic system. In addition to pile driving, the bottom pile gate system was used as a launching nose during launching. The SLJT was fitted with generators, compressors, pile drilling facilities and site containers etc.
The SLJT together with the crane had an operational weight of 850 tonnes.
The SLJT was required to be supported on two jetty bents with a 24m cantilever at the front end including the pile gates. The 55 tonne counter weights at the rear stabilised the SLJT during any crane operation.
John Holland Group