Highway Slope Manual

41
specifically identified and taken into account in the design of the remedial works. The
designer should decide on the minimum factors of safety to be adopted for the remedial works
design (i.e. to consider whether to design in accordance with Table 4.4 or 4.5), taking into
account the findings of the failure investigation and the degree of uncertainties involved.
Legend:
A
B
C
D
E
Princess Margaret Road (from Wylie Road to Pui Ching Road)
Pokfulam Road (from Pokfield Road to Mount Davies Road)
Castle Peak Road (from Sham Tseng to Siu Lam)
Borrett Road
Shouson Hill Road West
Notes: (1) The above nomograph corresponds to a reference landslide (i.e. 50 m 3 in volume) directly affecting
roads with different vehicular traffic densities (see Wong et al (1997b) for details).
(2) Information on actual AADT is given in the Annual Traffic Census and Statistics published by the
Transport Department. Design AADT values are given in the Transport Planning and Design
Manual (Transport Department, 1984).
(3) The design AADT, the expected AADT or the actual AADT, whichever is the highest, should be
considered. The AADT used should be documented in the Maintenance Manual to facilitate review
in future Engineer Inspections for Maintenance (GEO, 1998a).
(4) A to E are examples based on 1999 traffic census data (Transport Department, 2000).
Figure 4.1 Relationship between Roads with Different Traffic Density, AADT and Number of Road
Lanes