In a public sector design and build contract, the main contractor for Nicole Highway MRT circle line should have undertaken the following:-
(1) Submitting all design development in detailed shop drawings with evaluations and soil investigation tests to the requirements of LTA.
(2) Compliance with all site and soil conditions in carrying out the works.
(3) Warranting the design to meet all conditions, adequacy, suitability and integrity.
LTA should have obtained all these shop drawings and soil reports and method statements and endorsed its consent before proceeding with works.
Did report show presence of prevalent marine clay. How much quantities of water will be drained out from the surrounding and how dewatering will affect the subsidence of surrounding roads and bridges causing the whole roads and bridge structures to weigh in our the retaining wall below the excavated site.
If design and build contract is to be administered according to the contractual terms and conditions then there is no possibility of overlooking the need to strengthen the retaining wall sufficiently to prevent massive loading from the subsided roads and bridges or other structures.
The inquiry needs to be holistic and look at the big picture as well as the small picture at foremen and supervisors' level to get to the truths. Regards.
