October 4 - Yu Sin Engineering Work has utilised a Hydra-Slide HT300 heavy track hydraulic skidding system and TT900-10 engineered turntable to rotate a tunnel boring machine (TBM) at a major subway infrastructure project in Singapore.

The site is part of the Gardens By The Bay MRT Station project in Singapore.

The TBM, manufactured by Hitachi Zosen Corporation, measured 22 ft (6.7 m) in diameter and weighed 570 tons (520 tonnes).

The HT300 and TT900 combined to move and rotate the TBM in its entirety, at a location 100 ft (30 m) underground. After two days of preparation work and planning, the actual rotation was completed in one hour by skidding it onto the turntable, jacking down and rotating 180 degrees.

Jefferson Yee, general manager, Yu Sin Engineering Work, explained that initially the plan was to dismantle and reassemble [the TBM], but this would have taken a long time and the company wanted to explore the option of a reverse rotation. After consulting with Hydra-Slide on the technical possibilities it proceeded with the alternative option, which resulted in a huge time savings.

The TT900-10, which had already been lowered into the shaft using a 250-ton (226.8-tonne) capacity crawler crane, is more commonly used to turn transformers or generators during handling or installation, but it is suited to rotation of any heavy or oversized loads, claims Hydra-Slide.

Yu Sin ordered the TT900-10, a modification of Hydra-Slide's TT500-10, earlier this year.

Janine Smith, vice president at Hydra-Slide explained: "It is a simple system to operate. We have designed our turntables with the same safety principles as our skidding systems - there are no winch lines or holdbacks required, the push cylinders automatically reset into specially designed ratchets on the side of the turntable, and there is no manual handling of any components required during operation."