Geotechnical construction risk management at the Foothills Bypass – Hong Kong.

The Foothills Bypass is a dual 2-lane highway on the western side of Tuen Mun in the New Territories of Hong Kong. The road is constructed on 1.7 km of embankment along the foothills of Tsing Shan and on viaduct at its northern end where it links with a grade separated interchange. The stabilisation of a large area of existing instability (Area 19) formed a major and integral part of the works. Stabilisation included, staged excavation, deep trench drain installation, and filling works. Geological hazards that represented a risk to construction and long term performance of the project were; high pore pressures; low strength relict shear zones (φ΄r = 9˚); and collapse features. These geotechnical risks were managed by ensuring that the appropriate staff were engaged on site in combination with effective communication between site staff, the design team and the contractor. A key risk management tool was the continuous development of the conceptual ground model through all stages of the project.