TNAG-1415-FCO40-1896-Public-finance-in-Hong-Kong-1985 — Page 194

197.

Following completion of the two platforms a second site investigation was carried out to ascertain the cause of settlement and it was concluded that the most significant cause of the settlement was the compression of a layer of marine deposits below the level of the existing embankment although there may also have been other processes at work. Remedial works, which included a major change in design from the use of gravity walls to piled foundations, were then carried out as an extension to the contract and the contract sum was increased from $9 million to $20 million, of which $7 million was attributable to the remedial works. The final account of the contract, which included extra costs of $2 million because of the subsidence and the resultant delays in completion of the contract, was settled in January 1984.

198.

An audit review to ascertain the reasons for the problems encountered in the contract revealed that the initial site investigation did not include any laboratory testing and that the prescribed procedures requiring the submission of the design of the civil works for

geotechnical checking had not been complied with by the Railway Division of the Engineering Development Department despite repeated requests for information from the Geotechnical Control Office.

199.

The Director of Engineering Development has expressed the view that the initial site investigation was adequate to give sufficient information to the project engineer on whether comprehensive soil tests would be necessary, taking into consideration the fact that the existing embankment had been stable over the past seventy years and that changes to the length and level of the platform on the embankment were minimal. The Director has also expressed the view that, whilst compared with the second site investigation, the initial one may appear to have been inadequate, the two were different. The first was intended to provide essential information of the subsoil upon which the embankment had stood for some seventy years whilst the second one had to be thorough and searching to find out the cause of the settlement from all possible angles and also to provide the most economical remedial measures. The Director has stated that the modernization and electrification of the Kowloon-Canton Railway required the construction and reconstruction of 19 platforms by the Railway Division and the same extent of site investigation was carried out for each project. The University Station was the only project which required a redesign and this was caused by the exceptionally heavy rain during construction.