Highway Slope Manual

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event of a landslide should be based entirely on public safety considerations. This should be
made after a careful inspection and assessment of the site conditions, with due allowance
made for the anticipated weather (in particular, rainfall) conditions after the landslide and
other slope stability related factors. The highway engineer and maintenance staff engaged
by the road owner should take charge of the overall situation regarding remedial and urgent
repair works, with the advice of the geotechnical engineer. They should also initiate
effective actions with other relevant parties on any road closure and the arrangements for any
necessary traffic diversions, including liaison with the police and the transport authority.
Close liaison between the geotechnical engineer and the highway engineer should be
maintained in order that any follow-up actions for remedial and urgent repair works and reopening
of the road can be planned and implemented efficiently and effectively.
9.2.. Urgent Repairs
Where there is significant impact on the road users' safety, urgent repair works should
be arranged promptly by the road owner or his maintenance agent, who should ensure that a
suitable contractor is engaged to carry out the work. Where necessary, geotechnical advice
on urgent repair works needed to render a landslide area temporarily safe should be obtained
from a geotechnical engineer. Safety of emergency workers should be considered when
specifying urgent repair works. Effective communication should be maintained among the
various parties involved in the inspection of the landslide, preparation of the specification and
in supervision and acceptance of urgent repair works.
The type and extent of urgent repair works should be such that they can be completed
quickly to enable the re-opening of the road safely (see Section 9.2.5) and as early as possible.
For urgent repairs to soil cut slopes, the use of prescriptive measures as given in GEO Report
No. 56 (Wong et al, 1999) is recommended. Where time and site conditions permit, the
opportunity should be taken to carry out the repair works up to permanent work standards.
Wherever practicable, the geotechnical engineer should be informed after the landslide debris
on the road and slope has been cleared and before the slope surface is covered up, so that he
can carry out a follow-up inspection to verify the assumptions made in specifying the works
and amend the design of the works where necessary to take account of the ground conditions
revealed.
Simple items of work such as removal of landslide debris, local slope trimming,
surface protection and drainage diversion or improvement, etc., can be carried out by
contractors with proven general civil engineering experience such as those on the Works
Bureau list of approved contractors for site formation works or roads and drains. For more
substantial slope remedial and stabilisation works, use of contractors with landslide
preventive works experience, such as those on the Works Bureau list of approved specialist
contractors in the landslip preventive works category, is recommended. As-built records of
urgent repair works carried out should be prepared and these should be passed to the road
owner or his maintenance agent for retention and reference. Such records should be checked
by the supervising personnel to ensure that they accurately show the extent, the key
dimensions and the details of the works.
Upon completion of the repair works for a failed slope, an inspection of the slope
should be carried out by a geotechnical engineer as soon as practicable. The information