Highway Slope Manual

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Table 3.1 Potential Uses of Different Types of Information to be Collected at Desk Study Stage for a
Highway Proiect
Types of Information
Potential Uses
Topographical maps and 1:5 000 maps are useful for initial screening of key topographical constraints and
plans
hydrological and hydrogeological features along the highway route and within
the project study boundary and nearby. Larger scale maps, e.g. 1:1 000 maps,
are useful for examining individual slope features.
Hong Kong Geological Information on the geology and structure (e.g. faults) and engineering geological
Survey geological maps information within the project study boundary and nearby can be found from
and memoirs and relevant geological maps, memoirs and GASP Reports.
Geotechnical Area Studies
Programme (GASP)
Reports
Data in the Slope These are useful for locating sizeable existing man-made slope features within
Information System (SIS) the project study boundary and nearby. The SMRIS data can provide
and data from the Slope information on land and slope ownership status. Lease and engineering
Maintenance Responsibility conditions can be obtained from the Lands Department, i f required.
Information System
(SMRIS) maintained by the
Lands Department
Past landslide data and
study reports
Ground investigation and
laboratory test data
The Annual Rainfall and Landslides Reports and the Landslide Study Reports
together with the lessons learnt give useful information on and insights into the
types of problems that need to be solved for slope features within the highway
project study boundary and nearby.
These can provide subsurface geological and geotechnical information, including
the groundwater conditions and soil and rock joint shear strength data.
Aerial photographs These can provide information on site history and geomorphology. For
example, the presence of any old fills left on the downhill side of an existing
road when it was formed, and their extent, time of placement, and histories of
past failures, if any, can be assessed using available photographs.
Photolineaments which are often the surface expressions of geological structures
such as faults can also be identified. Furthermore, the aerial photographs can
be used to assess whether there have been significant past movements/signs of
distress at areas of natural terrain, an d whether drainage/stream courses, boulders
and other hazards are present and could affect the highway project.
Natural Terrain Landslide These can provide information on large-scale natural terrain landslides and
Inventory (NTLI), Boulder boulder falls, and landslides associated with man-made slope features within the
Field Inventory and project study boundary and nearby.
landslide database of the
GhO
Slope construction and These can provide an indication on the standard of construction (e.g. degree of
hngineer Inspection for compaction of fill embankments) and information obtained during maintenance
Maintenance records of existing man-made slope features. Record photographs can sometimes show
the ground conditions of highway slopes to different degrees of detail.
Services and utilities Information on the locations of such features and their age and maintenance (e.g.
information
records of leakage and bursts for water-carrying services) is useful for highway
slope design and stability assessment.
Note: Reference should be made to Appendices A and B of Geoguide 2 (GCO, 1987) for additional guidance.