Highway Slope Manual

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8. SLOPE MAINTENANCE AND UPGRADING
8.1 GENERAL
The recommended standards of good practice for slope maintenance are given in
Geoguide 5 (GEO, 1998a), which should be followed by all slope owners including owners of
highway slopes. General guidance on the inspection and maintenance of water-carrying
services affecting slopes is given in the Code of Practice on Inspection & Maintenance of
Water Carrying Services Affecting Slopes (Works Branch, 1996).
In order to reduce the risk of landslides, the Government of the Hong Kong SAR has a
long-term strategy to upgrade substandard man-made slopes including highway slopes under
a Landslip Preventive Measures (LPM) Programme (see Appendix D). However, owners
with a large number of roadside slopes to maintain should also develop their own programme
of upgrading substandard slopes to reduce the risk of landslides affecting their roads and the
road users.
This Chapter supplements the guidance given in Geoguide 5 and provides guidance to
highway slope owners for developing a maintenance and upgrading strategy and
implementing slope maintenance and upgrading works. The maintenance responsibility of
man-made slopes in Hong Kong is determined based on the principles given in WBTC
No. 26/99 (Works Bureau, 1999e).
8.2 SLOPE MAINTENANCE
Maintenance inspections for slopes include routine maintenance inspections, Engineer
Inspections (EI) for Maintenance, regular monitoring of any Special Measures (e.g.
prestressed ground anchors and horizontal drains) present, and regular checks of watercarrying
services and road drainage that could affect the slopes. Routine maintenance works
are usually required after maintenance inspections. Urgent repair works, preventive
maintenance works or stability assessments may also have to be carried out depending on the
outcome of the inspections.
In determining the frequency of routine maintenance inspection for highway slopes,
consideration should be given to the potential consequence-to-life and the seriousness of the
socio-economic consequence (e.g. possible major disruption to the community due to the need
to close a trunk road) in the event of a slope failure. There may be benefits to increase the
frequency of inspection to above the minimum levels as recommended in Geoguide 5 and in
the Code of Practice on Inspection & Monitoring of Water Carrying Services Affecting Slopes,
for slopes in the Consequence-to-life Category 1 or Economic Consequence Category A (see
Section 4.2).
Where routine maintenance inspections of slopes, slope drainage and associated road
drainage, monitoring of Special Measures and regular checks of water-carrying services are
carried out by different maintenance teams or parties, a co-ordinated approach should be adopted.
This should include a review of all records of maintenance inspections and works after a
complete cycle of routine maintenance inspection by the professional engineer responsible for