Highway Slope Manual

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2. PLANNING OF HIGHWAY PROJECTS
2.1 GENERAL
In planning new highway and road improvement projects, geotechnical aspects should
be considered together with other requirements in the early stages of the planning process.
The preferred route alignment and the associated optimum design options along the route
should be selected based on a balanced evaluation of the cost-effectiveness of the possible
alternatives taking into account all factors, including geotechnical requirements.
Reference should be made to Chapter 8 of the Hong Kong Planning Standards and
Guidelines (Planning Department, 1991) for guidance on the standards for planning land
requirements for highways. The Transport Planning and Design Manual (Transport
Department, 1984) and the Project Administration Handbook (PAH) for Civil Engineering
Works (Government of Hong Kong, 1992) contain useful information on planning and design
of transport infrastructure and planning of civil engineering project respectively. Reference
should be made to Chapter 3 of this Manual for guidance on site investigation for planning of
highway projects.
2.2 PLANNING OF HIGHWAY PROJECTS
2.2.1 Planning of New Highway Projects
Planning of a new highway is an iterative process which involves transport, highway,
environmental and geotechnical professionals. The process starts with the transport/highway
professionals putting forward possible route corridors through which a number of different
route alignments are to be examined. Geotechnical input should be introduced at this stage
to avoid areas with significant geotechnical hazards, where this is possible, and to select an
appropriate route alignment with optimum design options. Great benefits can be achieved
through a review of geotechnical aspects at this early stage of the planning process.
Geotechnical input for the planning of highway projects should initially consist of a
Geotechnical Review (GR) (see Section 2.3). If necessary, a Geotechnical Assessment (GA)
should also be carried out (see Section 2.4). The GR/GA should provide the relevant
information for determining the scope, land-take, cost and time requirements for the
investigation, design, construction and maintenance of the geotechnical works and hazard
mitigation measures. For Government projects, the project office should arrange to ca rry out
the GR at the Preliminary Project Feasibility Study (PPFS) Stage and the GA, if necessary, at
the Feasibility Study (FS)/Preliminary Design (PD) Stage as illustrated in Figure 2.1.
The project proponent should engage a geotechnical engineer to take charge of the
GR/GA. Such work demands a lot of judgement based on limited information. For this
reason, the geotechnical engineer needs to be a very experienced practitioner. He should
scrutinise all information collected and carry out the review/assessment personally; and
should maintain a close liaison with the highway planning personnel throughout the planning
process to provide timely geotechnical advice and recommendations for the completion of the
PPFS and FS/PD. He should also carefully estimate and recommend to the client the
geotechnical personnel requirements to be provided for the various stages of the project,
including the requirement to have a competent and experienced team leader to oversee the
investigation and design, and to scrutinize the quality of the geotechnical works at key stages.