Highway Slope Manual

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77 Table 9.1 Classification of Landslide Incidents Affecting Roads Incident Examples Classification Serious (a) An incident affecting a road with casualties or suspected casualties. (1) (b) An incident which has resulted in closure of a Category A Economic Consequence facility (e.g. an expressway, a trunk road or a primary distributor such as North Lantau Expressway, Tuen Mun <strong>Highway</strong>, Ching Cheung Road, etc. (2) ). (c) An incident which has resulted in closure of a sole access to critical services (3) , e.g. hospitals, fire stations, etc. (d) An incident affecting a road which necessitates a major evacuation of affected buildings. Landslide Inspection • Top priority should be assigned for inspection. • Road owner should mobilise a professional civil!highway engineer (or an equivalent level staff) from his maintenance team and the emergency contractor to attend the site inspection. • A geotechnical engineer (GE) should also be requested to inspect the site immediately. Significant An incident which is not minor but does not fall into the serious incident category. • Lower priority than serious incidents (4) . • A GE should be requested to inspect the site in a priority order on the basis of consequence and other factors such as available resource, traffic and weather conditions, geographic locations, etc. Minor An incident with no immediate consequence, e.g. a • Lowest priority. small-scale landslide say < 10 m 3 affecting a rural • Road owner, s maintenance road. For roads of a higher consequence category, staff to inspect the site first and the volume of debris should be less than 5 m 3 for the seek geotechnical advice if incident to be classified as minor. necessary. Notes: (1) The Fire Services Department being called out for a rescue operation for a slope failure affecting a road may be an indication of a serious incident. (2) A list of such roads (e.g. Red and Pink Routes) is maintained by the Transport Department and <strong>Highway</strong>s Department. (3) A list of such roads should be maintained by the road owners. (4) Incidents liable to develop into serious incidents should be accorded priority for site inspection. The factors that could have contributed to the slope failure should be carefully assessed during the landslide inspection, where site conditions permit. Figure 9.1 shows some of the common factors that may contribute to the failure of man-made slopes. In all cases, the road owner's maintenance staff with the assistance from the police should take immediate action (e.g. cordoning off the site) to safeguard the public prior to seeking the necessary geotechnical advice. Landslide inspection should not be confined to the boundary of a failed man-made slope feature. Where safe access is possible, inspection should be extended to cover the ground beyond the crest of the slope, if considered necessary, as well as the road and its drainage provisions above or below the slope, to identify areas of distress including tension cracks. Some distressed slopes may exhibit progressive movement but rapid failure may be triggered by subsequent heavy rain infiltrating into the tension cracks. Therefore, any
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HIGHWAY SLOPE MANUAL GEOTECHNICAL E
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2 。 The Government of the Hong Ko
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4 STEERING COMMITTEE: Geotechnical
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6 Page No. 3. SITE INVESTIGATION 33
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8 Page No. APPENDICES APPENDIX A -
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10 LIST OF FIGURES Figure No. Page
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12 LIST OF LATES Plate No. Page No.
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14 [BLANK PAGE]
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16 year (Evans et al, 1998), they h
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18 Plate 1.4 Landslide at Ching Che
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20 Plate 1.8 Steep Natural Terrain
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22 [BLANK PAGE]
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24 Notes: (1) The projects in the P
Page 27 and 28: 26 of the geotechnical hazards and
Page 29 and 30: 28 Table 2.2 Geotechnical Haards Th
Page 31 and 32: 30 for carrying out a GA is given i
Page 33 and 34: 32 [BLANK PAGE]
Page 35 and 36: 34 Table 3.1 Potential Uses of Diff
Page 37 and 38: 36 or features such as dykes or fra
Page 39 and 40: 38 movement monitoring and control
Page 41 and 42: 40 landslide debris, and the nature
Page 43 and 44: 42 Notes: (1) This Figure is based
Page 45 and 46: 44 Table 4.5 Recommended Minimum Fa
Page 49 and 50: 48 Plate 5.1 Surface Runoff Channel
Page 51 and 52: 50 Cascades, with cover where neces
Page 53 and 54: 52 (a) Trash Grill at Inlet of Cros
Page 55 and 56: 54 5.2.3 Drainage Improvement Works
Page 57 and 58: 56 For the control of visual impact
Page 59 and 60: 58 Plate 6.3 Pattern and Texture Pl
Page 61 and 62: 60 ighways are environments with a
Page 63 and 64: 62 Filling operations for a highway
Page 65 and 66: 64 Blasting is the most common meth
Page 67 and 68: 66 Notes: (1) The responsibility fo
Page 69 and 70: 68 Results of Rockfall Protective B
Page 73 and 74: 72 overseeing the maintenance of th
Page 75 and 76: 74 In addition to the slope upgradi
Page 77: 76 after each heavy rainstorm event
Page 81 and 82: 80 event of a landslide should be b
Page 85 and 86: 84 Federal Highway Administration (
Page 87 and 88: 86 Highways Department (1996). Mana
Page 89 and 90: 88 Wong, H.N., Pang, L.S., Wong, A.
Page 95 and 96: 94 key natural terrain and man-made
Page 97 and 98: 96 and details of all existing slop
Page 101 and 102: -AA (v) relevant services and utili
Page 103 and 104: -A2 (m) (n) 1dentify any statutory
Page 105 and 106: -A4 Notes: (-) An example of a prog
Page 109 and 110: 108 Wong, C.K.L. (1998). The New Pr
Page 111 and 112: 110 of slopes and slope owners and
Page 115: 114 (iv)subsidence of ground or roa
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