INTRODUCTION
Himalaya since Vedic times have been considered a vast repository of valuable medicinal herbs, minerals, forest resources etc. Vedic literature followed by the writings of Charaks, Susruta, Dhanwantri, Nagarjuna, Parashar, Balmiki and various other saints, bear testimony to it. "Alexander, The Great", who was much influenced because of its scenic beauty, bracing climate and agroclimatic conditions, made a great publicity of the Himalayan Herb Science in Yunan and Rome during middle ages (Anonymous, 1977; Chauhan, 1988). This potential, however, remained unexploited especially in higher reaches due to inadequate means of communication. After independence, Govt. of India, gave a special emphasis on road construction in order to bring socio-economic upliftment of tribal inhabitants. But due to lack of proper planning it resulted in serious ecological imbalances.
Society has now become aware of the environmental consequences resulting from road construction in hill areas. Right from the days of Vedas, our country has an age-old tradition of environment consciousness. During Samrat A shok is days social forestry was at its full swing having shady trees along the roads and fruit plants on the wastelands. In this paper efforts have been made to incorporate the latest techniques for protecting the environment after extensive survey of literature (Lone et al., 1992 and Chauhan
Hilly region pose unique problem for bridge construction. In a restricted hilly area itself climatic conditions, geological features and hydrological parameters vary considerably. Keeping in view the bridge site and various constraints, type of bridge and method of construction are to be selected carefully for safe, economical and successful completion of bridge construction.
Various challenges that come across while constructing bridges in hilly area are
1. Construction of bridge across deep gorges
2. Construction of bridge on rivers with bouldary beds
3. Construction of bridges in extreme temperature zones
4. Construction of bridges on sharp turn on highway
5. Landslide or Debris flow
Deep gorges, rivers with bouldary beds, extremely low temperature condition, high winds, landslide etc. in hilly regions require special attention to complete the activities of bridge planning and construction in a systematic way and are discussed here in.
Bridge Construction Overview
Planning and monitoring is basically what is to be done in due course of time, and how it is to be executed in the planned/allotted period for the particular bridge. All the pros and cons of the likely problems in the anticipated period need to be examined. Also the records of important points are made available at site with executives as follows:
Why the particular site was selected for the bridge.
Why particular type of bridge is proposed. (structural arrangement)
Site data
Proposal for preparation drawing.
Soil strata in the form of bore log.
Model study detail if already done for scour assessment.
Salient features of the bridge and quantities of each items involved.
Upto date approved structural drawings.
Details of all meetings and up to date decision if at all taken.
Decision making mechanism in case of any dispute i.e. Dispute Review Borad (DRB) be already finalized.
Bridge Foundation and Substructure
Foundation construction for any large bridge takes time. Problems encountered during construction of foundation depend upon type of foundation, soil strata encountered, equipment/plant deployed and logistic problems. Construction difficulties anticipated during the execution be kept in view while planning the works/ period for the job. Foundation can be opened foundation, pile foundation, well foundation or any other types of foundation. In case of well foundation, the various type of soil are encountered and it becomes difficult to give any clear time schedule about the sinking of wells unless the soil details are very clear and the anticipated profile matched with the actual encountered. In case of bouldery and clayey soil the rate of sinking schedule is likely to be slow when compared with the sandy soil. Also there may be requirement of pneumatic sinking technique subsequent to open grabbing due to difficulties in sinking of well. As the cost of pneumatic sinking is very high, this should be deployed judiciously. In such cases, there is need to keep the details of all the sinking difficulties in a systematic order and this can be reviewed in consultation with decision making authority. Review of soil parameter if required be given more attention and wherever required the details may be referred to material testing laboratory but within the time schedule. This may be helpful to recommend revision in foundation level, wherever possible based on soil data report. Tough strata in the foundation stage should be considered as engineering friendly
Superstructure
For particular site there are numerous structural arrangements possible. Final proposal be made based on the greater examination of site condition may be technical, aesthetic and construction methodology. Special care need to be taken in case of deep gorge where there is sizable difference between soffit level and bed level. This may pose difficulties for staging and shuttering. Proposal recommended for site should be well read in advance. After the proposal has been finalized for particular bridge, the construction can be planned. The quantities of each items involved and execution method be listed. Basically method statement should be kept ready for overall execution including job estimate. This data will be kept to ensure smooth progress of project.
Management of Construction Activities
Management of bridge construction demands that construction manager to reorient all the resources in such a way that the project is completed without any time/cost over run. Output of the work depend upon how best the activities are managed which will vary from site to site based on many factors. Based on the experience, various aspects be identified for efficient construction management. Schedule of construction based Critical Path Method (CPM) be prepared along with major milestone and Bar Charts. Latest software management tool can be used for this in case of a major bridge project. Design of Bridge is a post sanction in case of departmental construction and after tendering action in case of bridges throughout contract. It is necessary that design must be preceded by at least six to eight months or say 50% ahead of execution of concerned event. It has to be ensured that this should be completed well in time. Reviseddesign if any should be updated and clarified without delay. Observation on the approved design drawing if any be passed to design office immediately to make the changes. This is most important in case of foundation where design soil parameter needs to be adhered to. These may vary on actual execution and require review of design. To keep details with design office it is necessary that progress of foundation work be well informed to the design office.
Plant Management
Requirement of equipment/plant be assessed systematically and accordingly action may be taken to arrange this for a particular job.
Quantum of work covering all the items with specifications
Time available for work excution
Details of equipment and also minimum requirement as per job position.
Rated capacity of equipment/ plant
Assessed capacity
Schedule of maintenance
Inventory of spare parts required
Repair cover to equipment/plant
The layout should ensure minimum movement of material, equipment and personnel of the area is an essential condition, for operation of some equipment for example tower crane operation not possible at heavy winds speed. Stone crusher if required for site should be suitably located. Supporting facilities such as generator, office, stores should not be located in the path of dust, flow. The service road should be properly maintained. Receipt and despatch of equipment be kept in proper format to keep of details of its utilisation at site.
After staff has reported at site necessary action should be taken to utilise all the equipment. The required facilities for servicing and repair must be established to meet requirements.
Material Management
Material management is a parallel activity along with start of the Project. This cover procurement of camp material, office equipment, major purchased items, such as aggregates, sand, cement, steel, structural steel, shuttering consumables, electrical fittings. Forecasting of quantities and cost of various items on monthly basis must be done at least three to six months in advance which should be regularly reviewed.
Finance Management
No project or project management can be meaningful without this. In case of Government work the manager should get his budget fixed on monthly basis, on the basis of work done or minimum to be fed at site, on the decision of higher authorities. Key to measure financial planning lies in taking all above action and taking suitable measures at appropriate times to ensure that individual inputs are achieved to the maximum and capital investment kept at the lowest level.
Quality Management
Quality of work at site is most important activity and manager should always grapple to improve the same. Training to staff should be provided to update the quality control measure and it should become part of the work culture. At site laboratory be established to check the quality of concrete.
Tests be analysed at site based on the size of job. Mix design should be prepared based on the latest code and to produce the concrete of desirable strength. Compaction of concrete be given more attention before final setting. Latest guidelines issued by IRC and MORT&H be followed for systematic quality assurance. Quality assurance on ground improve the aesthetic of structures.
Safety Management
Safety of employees at site should be observed very seriously. All the workers be given briefing about the safety requirements based on the site hazards. Specially when the simply supported structure is attempted on deep gorge, suitable arrangement should be made to avoid any accident at site during insitu casting of superstructure. Also in case of foundation if the deep excavation is involved, the quality of surrounded soil be kept in view. There are incidents where few workers got buried in deep excavation due to sudden slide, this should be taken care. In case the well foundation is being attempted using double drum winch care need to be taken during grabbing process. During the diving process the proper coordination needs to be made between the diver and attendant to intimate about the problems if any, for which local signaling arrangements used, this can be finalised at site based on convenience. In case the pneumatic sinking is being used for well foundation, following safety measures, may be observed:
Accelerate circulation of air
Slow decompression
Duplicate and spare equipment
Illumination inside working chamber
Signaling arrangement
Caution about incidental loading
These precautions should be seriously followed to avoid any catastrophes at site. Safety management is also important in case on staging shuttering for superstructure. There are cases in the past where the collapse of shuttering/staging has led to loss of life. This needs check in before casting the superstructure. In case steel truss is being used as a staging arrangement, design and launching arrangement be thoroughly checked.
Documentation Management
Document management during the contract is an art in itself. Proper and systematic management of documents is utmost requirement for department as well as contractor. All the details should be property vetted by both the parties. Better documentation will avoid any disputes during the currency and after completion of contract (i.e arbitration cases areavoided). This needs special attention of the managers of both sides. Most of the cases being dealt by the arbitrator in our country, due to lack of understanding between two parties which, are further affected by improper documentation. In fact better documentation reflect the system of management in any project. Control estimate is required to be prepared annually to assess the job position. This should include work done till date and balance work in terms of money. This will be a guiding principle to progress the job in later period till completion. This practice is a must in all major bridge under construction. As project management has evolved, documentation has become a key skill particularly as projects become more complex and difficult. Organised documentation is the best defence against claims. Documentation that every project manager must have at their disposal are as under:
Proposal and Bid Estimates – These documents describe how the contractor envisioned the construction of the project and his plan to accomplish the work. It includes information about costs and schedule as well as construction methods.
Project Schedule - This is one of the most overlooked project records and it can provide the best documentation in a claim situation. The original baseline schedule sets the mark for monitoring the effects of any delays or unforeseen project disruptions.
Project Change orders – Any variances from the original contractual requirements must be documented and separated from the original scope of work requirements. Daily reports, time sheets, letters of correspondence and meeting minutes or any other documentation discussing agreements made between parties should be readily available.
Personnel Management
Manager should put the engineers, to activities they can perform better. Individual differences should be studied in detail to assign the suitable job to engineers, administration and account staff. Manager should be a good Psychologist to assign the work based on the inclination of the people at work. A considerable free hand be given to see what an individual can produce. He should be guided from time to time and work be kept on progress.
Decision making circulated, critical activities be cleared by manager after proper deliberations. Also care must be taken to select a new entrant suiting to the job for requirement.
Conclusion
With the changing scenario—there is urgent need to manage the bridge project effectively. Construction management basically is a tool to complete the project effectively within fixed amount but in less time. Manager should have knowledge sequence of all the activities. Decision making for both sides the contractor and the client needs to be fast and time bound otherwise the project will get delayed which will have cost over run. Control in form of reviewing monitoring has a catalyst effect to boost the progress.
PROBLEMS
There are a large number of ecological problems associated with road construction in hilly tribal areas, some of these can be summarized as below:
i) Deforestation: The association between deforestation and slope instability has been a subject of considerable research. Deforestation brings about erosion and soil movement is generally accepted, but opinions differ on its impact. So far as "Creeping" slopes are concerned, greater creep velocities are found in slopes covered by trees in the region of Queenland (Australia) than in slopes merely covered by grass in region of rain forests (Brown and Shen, 1975). Prandini et al. (1977) reported that deforestation leads to loss of mechanical strength imparted by rock system. Reinforcing power of roots is also demonstrated by the results of in situ block shear tests, which show that shear strength increases with increase in root density. At higher altitudes top green layer is very thin and takes hundreds of years to come. A large number of trees along the roadsides are falling down due to road construction. Improper road construction results in soil erosion that may lead to uprooting of large trees and degeneration of lower plants. This way it leads to serious ecological imbalances affecting adversely run-off factors, temperature gradient, surface radiation etc. Due to loss of vegetation, the velocity of run-off also increases that results in soil erosion, hence of soil-fertility.
ii) Disturbance of geological strata:Operations like blasting excavation, chipping of mountain slopes to come to desired accessibility, are involved during road construction in hill areas. These operations creates geological disturbance in the mountain body. The blasting operations set dynamic forces causing the movements of slip zones, cracks, fissures and weak planes. The geological havoc caused due to road construction in Kinnaur District in before us. The chronic problems of landslides at Tranda, Chaurah and Kadhra dhank are a few examples.
iii) Hill face disturbance: Natural inclination of hill face is disturbed by road cutting operation. Down hill movement of the land slides material and disposal of excavated mass from road construction degrade and deface the nature. Growth of vegetation is affected by the loss of topsoil that causes ecological imbalances.
iv) Drainage pattern interruption: Velocity of run-off at the down hills increases to a very large extent due to construction of bridges and culverts on the road as well as due to cutting for getting proper communication systems. This leads to eroding of banks and is a threat to the existence of trees and vegetation on the hill slopes. Sometimes lakes are formed by accumulation of debris from the excavated material and land slides. Such lakes formed force the water to flow through some other way destroying the side by flora e.g. at Nallah on NH = 22, bridge was washed away thrice in six years because due to debris river was blocked and a temporary lake was formed. Same story was repeated at Pabbar river in Chhawara valley (Rohroo) in 1992, where a big lake (2 miles) was formed and about ten villages were vacated in order to avoid any loss to human life. This lake formed resulted in a loss of large number natural wealth both flora and fauna. This way natural drainage pattern of the area is disturbed by road construction, which sometimes results in flash floods also.
v) Water resources disturbance: Natural water resources get disturbed due to blasting which is used during road construction activities. Moreover, improper disposal of fuel, lubricants used in the process contaminates the surface and ground water.
vi) Siltation problem: A large quantity of excavated material disposed on the down hill slopes is carried by the river that gets accumulated in the dams and reservoirs and reduce their life-span e.g. siltation rate of Bhakhra Dam reservoir is very large which is due to large scale road construction in Sutlej catchment.
vii) Destruction to flora and fauna:Wild life gets disturbed due to blasting, hauling of machineries, shriveling sound of road rollers and noise of moving vehicles on the up-gradient. Destruction of key habitats such as resting sites, hollow trees, feeding and breeding grounds occurs due to road constructions. Some of the flora and fauna gets destroyed out right due to intrusion into forest for road construction.
viii) Pollution: Tremendous pollution is created due to accumulation of debris down hill. Moreover, heating of bitumen through hot mix plants produces a large number of air pollutants like oxides of sulphur, nitrogen and carbon. Long chain aliphatic hydrocarbons and aromatic compounds are also the byproducts of this heating process, which are having carcinogenic property (Cancer producing) and special precautions must be taken for protecting the labourers working under such conditions on the road construction site. Surrounding temperature gets increased and atmospheric humidity is lowered due to movements of machineries and vehicles, altering the physiological processes of the plants and thereby affecting their growth pattern. The alterations in the surrounding conditions causes interference of micro-organism life in the soil.
ix) Destruction of medicinal wealth:In the hill areas of Himachal Pradesh out of 3000 species of identifies plants, over 500 species possess various kinds of medicinal properties. Hundreds of plants have ethno botanical importance. There are about 150 species of aromatic plants used in different kinds of cosmetics and having different medicinal properties. But due to improper planning in road construction and processes involved during road construction, the natural wealth gets destroyed costing crores of rupees in spite of protecting the atmosphere from pollution.
PROTECTIVE MEASURES
In order to maintain balance between the road construction activities and environment certain protective measures have to be taken. Some of these measures are as follows:
i) Environment impact assessment: Before starting the road construction operation, environmentalists must be consulted in order to avoid any ecological imbalance.
ii) Geological investigation: A geologist must be incorporated in the road construction work. Blasting and chipping of mountain slopes must be done under his instructions in order to avoid any geological havoc.
iii) State of wildlife: During the road construction loss to flora and fauna must be minimum. It should not be disturbed. An environmentalist must be consulted prior to road construction work.
iv) Avoidance of unstable and fissureal zones:Roads should not be constructed in lose soil and where erosion chances are more. In such cases the help of a soil Engineer must be taken, before starting any such activities.
v) Least disturbance to natural streams and gradients:Natural face of the hill must be least disturbed while constructing the roads. Only the required land must be used for the purpose.
vi) Restriction on reserve forests: Road construction activities must be minimum on reserve forests in order to avoid any disturbance to natural wealth. This will help in maintaining the ecological balance.
vii) Judicial way of doing work: While cutting and disposing the debris special care must be taken so that there is no soil erosion and loss to flora and fauna.
viii) Minimum blasting operations: Blasting practice during road construction must be to the minimum extent in order to avoid any dynamic forces causing movements of slip zones, cracks, fissures and weak planes.
ix) Half tunneling must be restored:In case of vertical rocky slopes half-tunneling must be restored.
x) Ropeway technique: In case of less densely thick population ropeway must be installed instead of going for road construction. This will provide protection to soil erosion, wild life and environment.
xi) Suitable drainage system: Along the entire side of the road, a suitable drainage system must be provided so as to avoid any flash flood, soil erosion, damage to vegetation etc.
xii) Restoration of natural springs and waterways:Natural springs and water resources must not be disturbed during road construction process, otherwise it will be a great challenge to the nature.
xii) Rebuilding of environment:
a) On suitable points, places must be provided that may act as scenic spots to the users.
b) Programme of social forestry must be taken upto the root level. The wastelands must be garlanded with trees, and valuable herbs and shrubs. The best example of social forestry is found in china where even single inch of wasteland is not left without plantation. Debris obtained during road cuttings must be accumulated at some appropriate place and plantation must be done on the same. This plantation will help in retaining the natural environment.
c) Plantation must be done along the banks of rivers, nallaha etc. in order to avoid any further cutting of soil and to protect the water reservoirs and dams from more siltation.
d) Small water tanks along with the proper drainage system must be constructed along the roadsides in order to protect both flora and fauna. Roadsides must be planted at war-level so as to give the best example of afforestation.
CONCLUSION
Although road construction in hilly areas causes a huge damage to both flora and fauna in spite of having adverse effect on environment, but without proper communication facilities, it is not possible to explore the valuable wealth of such areas. So a balance must be struck between the road construction and environment in order to minimize the ecological imbalance. Certain scientific measures must be taken into account while constructing the roads in hills. The balance between the two will lead to the prosperity of the region and no hazard to environment will occur.
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GEOTECHNICAL CHALLENGES IN SLOPE ENGINEERING OF
INFRASTRUCTURES
Slopes within infrastructures sometimes slide and cause damage and inconvenience to the public.
Some of these landslides have claimed lives. Landslides include newly completed slopes, such as
the recent failure at Putrajaya as well as old slopes, such as the collapse of the rock slope of the
PLUS Expressway at Bukit Lanjan (2003), which was completed more than ten years ago.
The most notorious one was the collapse of a slope with rubble walls bringing down the Tower 1
Apartment of Highland Towers and killing 48 people on 11 Dec 1993. The towers were built in
1978.
A review of the causes of landslides indicates that most of the landslides are man-made slopes
and are mainly due to design deficiency (Gue & Tan 2006). This keynote also discusses some of
the recent and older failures, the causes of failures, and outlines some suggestions to mitigate
future occurrence.
Keywords: Slope Engineering, Infrastructure, Research & Development (R&D), Culture
1. INTRODUCTION
With the increased developments that have encroached into the hilly areas over the past two
decades, Malaysia experiences frequent landslides with a number of major slope failures which
cause damage and inconvenience to the public. These landslides include newly completed slopes,
such as the recent failure at Putrajaya in 2007 as well as old slopes, such as the collapse of the
rock slope of the PLUS Expressway at Bukit Lanjan (2003), which was completed more than ten
years ago. Some of these landslides have claimed lives. The notorious collapse of Tower 1
apartment of Highland Towers claimed 48 lives in 1993.
Climate conditions in Malaysia are characterized by relatively uniform temperature and pressure,
high humidity and particularly abundant rainfall with annual rainfall intensity over 2500mm.
Most of the landslides in two monsoon seasons of Malaysia are induced by the high rainfalls and
more than 80% of landslides were caused by man-made factors, mainly design and construction
errors. (Gue & Tan 2006)
Many will still remember the collapse of the Highland Tower on 11 Dec 1993. Since then, there
have been other major landslides resulting in fatalities and severe losses and destruction of
property. A brief discussion of these major landslides and their causes is presented here. This key
note also outlines some suggestions to mitigate future occurrence.
1 CEO, G&P Professionals Sdn Bhd & Managing Director of G&P Geotechnics Sdn Bhd Kuala Lumpur, Malaysia
2 Associate, G&P Geotechnics Sdn Bhd, Kuala Lumpur, Malaysia
2. MAJOR LANDSLIDES IN MALAYSIA
Among the major landslides occurring in the past two decades, the most notorious landslide was
the collapse of a slope with rubble walls, bringing down Tower 1 Apartment of Highland Towers
and killing 48 people on 11 Dec 1993. The towers were built in 1978.
Major landslides occurring within infrastructure seldom result in loss of lives compared to those
occurring in residential areas. However, major landslides that occurred within infrastructures
have resulted in great economic loss to the public and business due to disruption to the
transportation network and property damage.
The following table summarises some of the major landslides with their consequences: -
DATE OF
OCCURENCE
LANDSLIDE
LOCATION
(NAME)
CATEGORY FATALITY
(NOS)
DISRUPTION TO
TRANSPORTATION
NETWORK
11 Dec 1993 Highland Tower Residential 48 No
20 Nov 2002 Taman Hillview Residential 8 No
26 Oct 2003 Bukit Lanjan Highway - Yes
12 Oct 2004 Gua Tempurung Highway 1 Yes
23 Mar 2007 Putrajaya Public
Amenities - No
13 Nov 2007 Pulau Banding Public
Amenities - No
Table 1: Major Landslides with their Consequences in Malaysia
(After Abdullah et al. 2007)
2.1 Collapse of Tower 1 of Highland Towers Apartment, 1993
The Highland Towers Condominium is located in the district of Hulu Kelang, Selangor. Highland
Towers consisted of three blocks 12 storey high apartments named simply Block 1, 2 and 3
respectively. It was constructed between 1975 and 1978. Block 1 was completed and occupied in
1979. Tower 1 therefore collapsed 14 years after completion.
Figure 1 shows the water path before and after the completion of the Highland Tower
Apartments. In the course of the Highland Towers development, the stream was diverted by
means of a pipe culvert to flow northwards across the hill slope directly behind Highland Towers.
The approved drainage system on the hill slope behind Highland Towers was never completed.
Figure 1 shows the water path before and after the completion of Highland Towers.
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Aerial Photo 1975 (Before Completion) Aerial Photo 1993 (After Completion)
Figure 1: Water Path Before and After Completion of the Highland Towers Apartments
On Saturday, 11 Dec 1993, at about 1.30p.m., after 10 days of continuous rainfall, Block 1
collapsed and killed 48 people. The cumulative daily rainfall intensity measured from 1st to 10th
December 1993 recorded at JPS Ampang was 177.5mm and the measured maximum daily
rainfall intensity was 59.5mm. It was not exceptional rainfall as compared to previous measured
rainfall intensity.
An investigation was carried out by experts and specialists assembled by Majlis Perbandaran
Ampang Jaya (MPAJ) and was published in a report titled “Report on the Inquiry Committee in
the Collapse of Block 1 and The Stability of Blocks 2 and 3 Highland Towers Condominium,
Hulu Klang Selangor Darul Ehsan” in 1994. The report concluded that the most probable cause
of the collapse of the tower was the buckling and shearing of the rail piles foundation induced by
the movement of the soil. The movement of the soil was the consequence of retrogressive
landslides behind the building of Block 1.
The landslide was triggered by inadequate drainage on the hillslope that had aggravated the
surface runoff (MPAJ 1994). Slope and rubble walls behind and in front of Block 1 were also
found to be improperly designed with an overall Factor of Safety of less than 1. Figure 2 shows
the sequence of retrogressive failures that took place, causing large soil movement and piling up
behind Block 1 and causing an increase in lateral pressure to the foundation of the building and
the rubble wall in front of the Block until it collapsed and was followed by the toppling of the
apartment. Figure 3 shows the collapse of Block 1 of the Highland Tower Apartments.
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Figure 2: Illustration of Retrogressive Slope Failure Sequence (after Gue & Tan 2002)
Figure 3: Collapse of Block 1 of Highland Towers Apartments, 1993
2.2 Collapsed Bungalow at Taman Hillview in Ampang, 2003
The collapse of a double storey bungalow at Taman Hillview in Ampang (Figure 4) occurred on
20 Nov 2002 and claimed 8 lives. The cause of landslide at Taman Hillview was similar to the
Highland Towers tragedy, where failure of a rubble wall again triggered a landslide. The Factor
of Safety of the rubble wall in the Highland Towers was found to be less than 1.0 even without
Reduced Level (m)
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considering any presence of geological features such as relic joints etc and water tables. In fact,
the rubble wall is part of the series rubble walls behind Highland Towers.
Figure 4: Collapsed Bungalow at Taman Hillview in Ampang, 2003
2.3 Rock Slope Failure at Bukit Lanjan, 2003
On 26 Nov 2003, a massive rock slope failure occurred at Bukit Lanjan Interchange which is part
of the New Klang Valley Expressway (Mohd. Asbi et al. 2007). The failure occurred
immediately after a period of heavy rainfall. The substantial large volume of rock debris (approx.
35,000m3) that came to rest on the expressway blocked the expressway completely and forced the
entire stretch of the expressway to be closed for 6 months for rehabilitation works (Figure 5).
Immediately after the failure, the Highway Concessionaire commissioned site investigations that
included surveys, geological mapping, deep boreholes and laboratory tests to assess the likely
causes of failure and also to provide geotechnical information required to design for
rehabilitation of the failed slope. From the site investigation results, it was inferred that the rock
slope failure was a complex wedge type failure. The wedge was formed by two discontinuities
that daylighted out of the slope and the third discontinuity acted as a release plane. It was also
demonstrated that for the failure to occur there was a requirement for water pressure to be acting
on the potentially unstable wedge. Figure 5 shows the elevation and plan view of the failed rock
slope.
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Figure 5: Rock Slope Failure at Bukit Lanjan, 2003 (newspaper cutting, New Straits Times)
2.4 Debris Flow at KM302 of PLUS North-South Expressway Near Gua Tempurung,
2004
Two lanes for southbound traffic bridge of KM302, North–South Expressway near Gua
Tempurung were closed for three months for rehabilitation works as the result of a debris flow
that occurred on 12 Oct 2004. Tonnes of earth, boulders and trees went crashing down the hill
slope in this incident, as illustrated in Figure 6. Three beams of the bridge were damaged and had
to be replaced. This incident also caused one casualty, public and economic losses and a great
inconvenience to the public.
Figure 6: Debris Flow at KM 302 of PLUS Expressway, 2004
(newspaper cutting, Nanyang Siang Pau)
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2.5 Slope Failure at Putrajaya, 2007
On 22nd March 2007, a massive slope failure occurred at Precinct 9, Putrajaya which twenty-three
vehicles were buried in this landslide and forced about 1,000 residents to vacate their homes at
4.30am. This slope failure involved a 50-metre high hill with a man-made slope about 45 degrees
which was located about 10 metres from the 15-storey apartment. It had been raining heavily in
Putrajaya since the evening of 21 March 2007 till the early morning of 22 March 2007 before the
slope failure happened. Figure 7 shows the collapsed slope with buried vehicles.
Figure 7: Slope Failure at Precinct 9, Putrajaya, 2007
2.6 Collapse of Tourism Complex in Pulau Banding, 2007
Before the collapse of the Tourism Complex at Pulau Banding, Perak on 13th November 2007,
the complex was sitting on a hill slope with its toe near to the edge of the lake, Tasik Temenggor.
The slope extended down into the lake where the water level fluctuates to about 4 meters without
toe protection in the area of fluctuation. The building was completed in 2004. The 15-room
resort was not occupied, as defects such as cracks were found in the buildings. It was reported
that a few months before the failure, a few piles beneath the columns of the building were found
exposed and deflected. On 10th November 2007, part of the building collapsed, followed by a
total collapse of the whole building on 13th November 2007.
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Figure 8: Collapse of Tourism Complex in Pulau Banding, 2007 (The Star, 15 Nov 2007)
3. WHY LANDSLIDES: FACTORS ATTRIBUTED TO LANDSLIDES
A study of the causes of landslides such as design errors, construction errors, design and
construction errors, geological features and maintenance had been carried out by Gue & Tan
(2006) based on 49 investigation cases of primarily large landslides on residual soils. The results
of the study are shown in Table 2.
CAUSES OF
LANDSLIDES NUMBER OF CASES PERCENTAGE (%)
Design Errors 29 60
Construction Errors 4 8
Design and Construction
Errors 10 20
Geological Features 3 6
Maintenance 3 6
Total 49 100
Table 2: Causes of Landslides (after Gue & Tan, 2006)
The results of the study indicate that 60% of the failures are due to inadequacy in design alone.
The inadequacy in design is generally the result of a lack of understanding and appreciation of
the subsoil conditions and geotechnical issues. Failures due to construction errors alone either of
workmanship, materials and/or lack of supervision contributed to 8% of the total cases of
landslides. About 20% of the landslides investigated are caused by a combination of design and
construction errors. For landslides in residual soil slopes, the landslides caused by geological
features only account for 6% which is same as the percentage contributed by a lack of
maintenance.
Before After
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3.1 Geological Features
Landslides due to geological features contributed to about 6% of the total failures investigated.
However, it should be recognised that these geological features, such as discontinuities in
residual soils, especially sedimentary formations, are not usually detectable during the design
stage even with extensive subsurface investigation (boreholes, geophysical methods) by an
experienced engineering geologist or engineer who carries out geological mapping at the site
prior to cutting. Most of these geological features can only be detected after exposing the slopes
during excavation. In view of this, it is best to carry out confirmatory geological slope mapping
of the exposed slopes after excavation, by an experienced engineering geologist or geotechnical
engineer to detect any geological discontinuities that may contribute to potential failure
mechanisms, namely planar sliding, anticline sliding, active-passive wedges, etc. Figures 9 and
10 show the discontinuities found during excavation which were otherwise almost impossible to
detect.
By understanding that geological discontinuities could not be fully addressed during the design
stage, design engineers should make conservative assumptions about the soil/rock parameters and
also the groundwater profile to ensure adequacy in design and should only carry out adjustments
on site after geological slope re-mapping and re-analysis of the slopes. On the contrary, when
optimistic assumptions are made and the results obtained during construction on sites that are less
favourable then expensive options such as retaining walls or slope strengthening using soil nails
are required due to space and boundary constraints. Thus the safety of slopes is often
compromised due to unbudgeted strengthening and additional protection works being needed.
Figure 9: Block Failure of Sedimentary Formation (After Liew S.S. 2005)
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Figure 10: Inconsistent Weathering Profile (After Liew S.S. 2005)
3.2 Design and Construction Errors
The majority of these failures investigated by Gue & Tan (2006) were avoidable if extra care was
taken and input from engineers with relevant experience in geotechnical engineering was sought
from planning to construction. Many of the landslides which were caused by design errors
reported above were due to the following:-
1) The abuse of the prescriptive method on the slope for cut or fill slopes without proper
geotechnical analyses and assessment. It is very common in Malaysia to find many cut
slopes formed for residual soils that are 1V:1H (which means one vertical: one horizontal =
45 degrees angle). Based on literature published on residual soils and the authors’ own
experience of residual soils, it is not likely, or impossible, for residual soils to have the
effective parameters (c’, φ’) to maintain the stability of the slopes even without water table
and geological features unless it is not a soil slope but a rock slope. The authors’ own
experiences indicates that the φ’ values of residual soils generally ranges from 29o to 36o and
mainly depend on the particle size distribution of the materials. Therefore, if proper analysis
of the slopes’ stability was carried out with correct soil parameters, most of these 45o gradient
slopes would not have a sufficient Factor of Safety (FOS) recommended against slip failure
in the long term, even with some effective cohesion. In summary, engineers should not only
follow the slope gradients (e.g. 1V: 1H) that have been done previously, without proper
geotechnical analysis and design.
2) Subsurface investigation (S.I.) and laboratory tests were not carried out to obtain
representative soil parameters, subsoil and groundwater profiles for design and analysis of
slopes. Therefore, the analysis and design carried out are not representative of the actual site
conditions, and are thus unsafe.
3) A lack of good understanding of fundamental soil mechanics, so that the most critical
condition of cut slopes is in the long term (in the “Drained Condition”). Therefore, it is
necessary to adopt effective shear strength parameters for the “Drained Analysis” of the cut
slopes in residual soils instead of undrained shear strength (su or cu).
For landslides that were caused by construction errors alone or combined with design, the
common construction errors are as follows:-
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1) Tipping or dumping of loose fill down the slopes to form a filled platform or filled slope.
This is the most rampant construction error for earthworks construction in Malaysia.
Contractors carrying out the filling works on slopes will find it most “convenient” and “easy”
to dump or tip soil down the slopes to form the fill. The condition is worsened by not
removing the vegetation on the slopes, causing the bio-degradable materials to be trapped
beneath the dumped fill, forming a potential slip plane with the bio-degradable materials
(vegetation). The uncompacted fill slopes, having a very low Factor of Safety, will likely fail
in the long term.
2) Errors in the construction method, such as forming cut slopes by excavating slopes from the
bottom (undermining) instead of the correct practice of cutting from the top downwards. This
wrong practice will trigger landslides or induce potential shear planes extending beyond the
proposed cut slope profile.
3) Over-excavation of cut slopes. Contractors unintentionally over-excavate cut slopes and then
try to fill back the excavated materials to reform the slope to the required gradient. The
uncompacted loose materials will eventually slip down.
The way to prevent these bad construction practices is to have proper full-time supervision by
members of the design consultant together with reliable and responsible earthwork contractors
having clear approved method statements for construction. Failure of slopes and retaining walls
can also take place if the temporary works (e.g. temporary excavation) are not properly designed
and constructed.
3.3 Maintenance
Poorly maintained slopes can lead to slope failure. These may include amongst others,
damaged/cracked drains, inadequate surface erosion control and clogged drains. The common
problems of landslides caused by a lack of maintenance are blockage of drains for surface runoff,
and erosion. Blockage of drains will cause large volumes of water to gush down a slope
causing erosion to the slope and the formation of gullies. These gullies will further deteriorate
into big scars on the slopes and will finally lead to landslides.
Figure 11 shows the formation of rills and gullies and Figure 12 shows localized landslips caused
by erosion which will propagate with time into landslides if erosion control is ignored. If proper
maintenance is carried out, then all these small defects would have been rectified and landslides
caused by erosion would be prevented.
4. GOOD DESIGN AND CONSTRUCTION PRACTICES FOR SLOPE ENGINEERING
4.1 Planning, Analysis and Design of Slopes
Desk Study
Desk study includes reviewing of geological maps, memoirs, topographic maps and aerial
photographs of the site and adjacent areas so that the engineers are aware of the geology of the
site, geomorphology features, previous and present land use, current development, construction
activities, problem areas like previous slope failure, etc.
Site Reconnaissance
Site reconnaissance is required to confirm the information acquired from the desk study and also
to obtain additional information from the site. For hillsite development, it is also very important
to locate and study the landslip features to identify previous landslides or collapses that can act as
indicators of the stability of the existing slopes.
Subsurface Investigation
Subsurface investigation (SI) should be properly planned to obtain representative subsurface
condition of the whole slope such as general depth of soft soil, hard stratum, depth of bedrock,
geological weak zones, clay seams or layers, and the groundwater regime. The planning of
exploratory boreholes should take into consideration the slope profile instead of following a
general grid pattern. A minimum of three (3) boreholes per cross-section (one on slope crest, one
at mid-slope and one at slope toe) is recommended so as to obtain representative subsurface
conditions of the whole slope.
Analysis and Design of slopes
For the design of the slopes, correct information on soil properties, the groundwater regime, the
geology of the site, selection and methodology for analysis are important factors that require the
special attention of the design engineer. A detailed analysis of soil slopes can be found in Tan &
Chow (2004) and Gue & Tan (2000).
For the selection of Factor of Safety (FOS) against a slope failure, the recommendation by
Geotechnical Manual for Slopes (GCO, 1991) of Hong Kong with minor modifications to suit
local conditions is normally selected with consideration of two main factors, namely, Risk-to-life
or Consequence to life (e.g. casualties) and Economic Risk or Consequence (e.g. damage to
property or services). Further details on selection of FOS can be found in Gue & Tan (2004).
Design of Cut and Fill Slopes
The vertical interval of slopes between intermediate berm is usually about 5m to 6m in Malaysia.
GCO (1991) recommends that the vertical interval of slopes should not be more than 7.5m. The
berms must be at least 1.5m wide for easy maintenance. The purpose of berms with drains is to
reduce the volume and velocity of runoff on the slope surface and the consequent reduction of
erosion potential and infiltration. The adopted slope gradient should depend on the results of
analysis and design based on moderately conservative strength parameters and representative
groundwater levels.
For fill slopes before the placing of fill, the vegetation, topsoil and any other unsuitable material
should be properly removed. The foundation should also be benched to key the fill into an
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existing slope. A free-draining layer conforming to the filter criteria is normally required
between the fill and natural ground to eliminate the possibility of high pore pressures from
developing and causing slope instability, especially when there is an existing surface or
intermittent streams and depressions. Sufficient numbers of discharge drains should be placed to
collect the water in the filter layer and discharge it outside the limits of the fill and away from the
slopes.
Surface Protection and Drainage
Surface drainage and protection are necessary to maintain the stability of the designed slopes
through reduction of infiltration and erosion caused by heavy rain, especially during monsoon
seasons. Runoffs from both the slopes and the catchment areas upslope should be effectively cut
off, collected and led to convenient points of discharge away from the slopes. Details on surface
protection and drainage can be found in Gue & Tan (2004).
Catchment Study
Catchment study is rarely carried out for the provision of surface drainage capacity to carry the
runoffs in current slope engineering practice. Under-provision of surface and subsurface
drainages can lead to infiltration and spillage of the surface runoffs to the slopes, cause saturation
of slopes, surface erosions to the slopes and can result in slope deterioration with time.
Fill Slopes Over Depressions or Valleys
Depressions or valleys are the preferred water path of natural surface runoffs. Streams or
intermittent streams are usually formed at these depressions and valleys, especially during heavy
rain. In the meantime, intermittent streams at depressions or valleys will also transport sediments
from upstream and deposit these sediments at the depression or valley and form a layer of soft or
loose material and debris.
For slopes which are formed by filling over a depression or valley, the possibility of having
saturation of slopes and developing slip planes through the pre-existence of weak soft or loose
layers with debris is high.
Therefore, extra care should be exercised on the fill slopes over depressions or valleys by
adopting the following measures to mitigate occurrence of slope failure: -
1) To provide adequate surface drainage by calculating the capacity required based on
catchment study to reduce infiltration of surface runoffs to the slopes.
2) Subsurface drainages should be adequately provided to drain out water from a slope to
avoid saturation of the slope and rising of the groundwater level. Increases in ground
water levels will reduce the FOS of the slope.
3) To replace shallow weak materials by compacted good fill material during the filling
works to enhance the slope stability FOS.
Slopes Next to Water Courses
For slopes next to water courses such as river bank slopes, beaches, pond side slopes, etc, the
slope should be robustly designed by considering the probable critical conditions such as
saturated slope with rapid drawn-down conditions, scouring of slope toe due to flow and wave
actions, etc. Properly designed riprap or other protection measures are needed over the tidal
range.
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4.2 Construction Controls
Supervision and Coordination
The supervising personnel should have sufficient knowledge and experience in geotechnical
engineering to identify any irregularities of the subsurface conditions (e.g. soil types, surface
drainage, groundwater, weak planes such as clay seams etc.) that might be different from those
envisaged and adopted in the design. Close coordination and communication between design
engineer(s) in the office and supervising engineer(s) are necessary so that modification of the
design to suit the change of site conditions could be carried out when needed. This should be
carried out effectively during construction to prevent failure and un-necessary remedial works
during the service life of the project. Site staff should keep detailed records of the progress and
the conditions encountered when carrying out the work in particular if irregularities like clay
seams, significant seepage of groundwater are observed. Sufficient photographs of the site
before, during and after construction should be taken. These photographs should be supplemented
by information such as dates, weather conditions or irregularities of the subsoil conditions
observed during excavation.
Filling of Slopes
Whenever possible, construction programmes should be arranged such that fill is placed during
the dry season, when the moisture content of the fill can be controlled more easily. When filling,
tipping should not be allowed and all fill should be placed in layers not exceeding 300mm to
450mm thick depending on the type of compacting plant used (unless compaction trails proved
that thicker loose thickness is achievable) in loose form per layer and uniformly compacted in
near-horizontal layers to achieve the required degree of compaction before the next layer is
applied. The degree of compaction for fill to be placed on slopes is usually at least 90% to 95%
of British Standard maximum dry density (Standard Proctor) depending on the height of the slope
and the strength required.
Cutting of Slopes
Cutting of slopes is usually carried out from top-down followed by works like drains and turfing.
When carrying out excavation of the cut slopes, care must be taken to avoid overcutting and
loosening of the finished surface which may lead to severe surface erosion. Minor trimming
should be carried out either with light machinery or by hand as appropriate. It is also a good
practice to construct first the interceptor drains or berm drains with proper permanent or
temporary outlets and suitable dissipators before bulk excavation is carried out or before
continuing to excavate the next bench.
Surface Protection of Slopes
For all exposed slopes, slope protection such as turfing or hydroseeding should be carried out
within a short period (not more than 14 days and 7 days during the dry and wet seasons
respectively) after the bulk excavation or filling for each berm. All cut slopes should be graded
to form suitable horizontal groves (not vertical groves) using suitable motor graders before
hydroseeding. This is to prevent gullies from forming on the cut slopes by running water before
the full growth of the vegetation, and also to enhance the growth of vegetation.
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4.3 Maintenance of Slopes
Guideline for Slope Maintenance
A good guideline from GEO of Hong Kong such as “Geoguide 5 – Guide to Slope Maintenance”
(2003) for engineers and the “Layman’s Guide to Slope Maintenance” which is suitable for the
laymen should be referred to.
Geoguide-5 (2003) recommends maintenance inspections be sub-divided into three categories:
(A) Routine Maintenance Inspections, which can be carried out adequately by any responsible
person with no professional geotechnical knowledge (layman).
(B) Engineer Inspections for Maintenance, which should be carried out by a professionallyqualified
and experienced geotechnical engineer.
(C) Regular Monitoring of Special Measures, which should be carried out by a firm with
special expertise in the particular type of monitoring service required. Such monitoring is
only necessary where the long term stability of the slope or retaining wall relies on
specific measures which are liable to become less effective or deteriorate with time.
Frequency of Maintenance Inspections
Since Malaysia has at least two monsoon seasons, Routine Maintenance Inspections (RTI) by a
layman should be carried out a minimum of twice a year for slopes with negligible or low risk-tolife.
For slopes with high risk-to-life, more frequent RTI is required (once a month). In addition,
it is good practice to inspect all the drainage channels to clear any blockage by siltation or
vegetation growth and repair all cracked drains before the monsoon. Inspection should also be
carried out after every heavy rainstorm.
Category B Engineer Inspections for Maintenance, should be taken to prevent slope failure when
the Routine Maintenance Inspection by laymen observed something unusual or abnormal, such as
the occurrence of cracks, settling ground, bulging or distorting of walls or settlement of the crest
platform. Geoguide-5 (2003) recommends as an absolute minimum that an Engineer Inspection
for Maintenance should be conducted once every five years or more as requested by those who
carry out the Routine Maintenance Inspections. More frequent inspections may be desirable for
slopes and retaining walls in the high risk-to-life category.
5. SUGGESTIONS FOR IMPROVEMENT OF THE ENGINEERING AND
MANAGEMENT OF SLOPES
5.1 Practitioners and Professionals in Slope Engineering
The institution of Engineers, Malaysia (IEM), under its own initiative, formed a taskforce in 1999
to formulate policies and procedures for mitigating the risk of landslides in hilly terrain
developments. IEM (2000) produced a report entitled, “The policies and procedures for
mitigating the risk of landslide on hill-site development” with the aim of providing uniform,
consistent, and effective policies and procedures for consideration and implementation by the
Government of Malaysia. However, the recommendations by IEM were not immediately
accepted and acted on by the Government (C.H. Abdullah et al. 2007).
Practitioners and professionals that involve in slope engineering works should practice ethically
and professionally and should only practice in the area of their expertise to ensure the safety of
the design and to mitigate the risk of landslides.
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Stakeholders such as engineering universities and colleges, the Association of Consulting
Engineers Malaysia (ACEM) and the IEM should work together to develop a series of structured
training modules on slope engineering so as to inculcate better understanding of the practitioners
so that the public could benefit.
Apart from having structured training modules, all practitioners should also think another step
ahead on how to further improve the current slope engineering practices through Research and
Development (R&D) to enhance safety, speed of construction and economical aspects. It is
important to equip practitioners with R&D skills to improve construction industry’s
competitiveness and to prepare ourselves for globalisation.
A successful example by Hong Kong Geotechnical Engineering Office (GEO) on suggesting a
new cost-effective and eco-friendly method of natural slope stabilisation through R&D
(Campbell et al. 2005) is discussed in the following section.
In 2003, the Hong Kong GEO completed a planting trial involving the use of native small tree
and shrub species on steep slopes. Based on this, guidelines were promulgated on the selection of
suitable vegetation species for man-made slopes. Trials were also initiated on repairing natural
terrain landslide scars by means of predominantly native vegetation species (Figure 13). The
interim findings are documented by Campbell et al. (2005).
(a) Landslide scar prior to (left) and during (right) installation of bioengineering measures
(b) Landslide scar during (left) and after (right) installation of bioengineering measures
Figure 13: Use of Bioengineering Measures for Repair of Natural Terrain Landslides
(after Wong & Ho 2006)
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5.2 Slope Management in the Public Sector (Abdullah et al. 2007)
The first to document on guidelines in hilly areas development was the Urban and Rural Planning
Department in 1997. The guidelines addressed the issues of planning and development in
highlands, on slopes, natural waterways, and water catchment areas. In June 2002, the Geology
and Minerals Department of Malaysia produced guidelines on hillsite development. The
guidelines considered the angle of the natural slopes and geology of the area. The areas were then
classified into 4 categories which were termed as Class l, ll, lll and lV. Class l is the least severe
in terms of terrain grading whereby slope angles are less than 15o. Class lV was the highest risk,
where, absolutely no development will be allowed in this area.
Also in June 2002, the National Disaster Management Committee in the Prime Minister’s
Department directed Jabatan Kerja Raya (JKR) to form a Working Group on Landslide Study
with the objectives of identifying areas with high landslide risks and coming up with mitigative
measures. The Working Group was officially inaugurated on August 14, 2002 and subsequently 4
subcommittees were formed, namely (Abdullah et al. 2007):
• Sub-committee for Forensic Investigation of landslides
• Sub-committee for Disaster Management during landslides
• Sub-committee for Co-ordination and Information Sharing
• Sub-committee for Research Coordination.
The first task given to the committee was to investigate the Taman Hillview landslide that killed
eight (8) people at the end of 2002. The overall mandate given to JKR during this time was not
very successfully implemented because the Slope Engineering Unit was then placed under the
Road Maintenance Division, where it had to compete for attention and resources within the
division.
The Slope Engineering Branch (CKC) was established as a branch within the JKR in February
2004 with the aim of managing and monitoring of slopes throughout the country. CKC has 6
units that deal with slope matters. They are the Slope Safety Unit that coordinates and controls
the budget for the slope repair works; the Slope Management Unit that collects spatial and non
spatial data and produce hazard maps for slopes; the IT and Documentation Unit whose job is to
archive and disseminate slope data and information through the website and by archiving; the
Research and Development Unit whose function includes research, initiating cooperation with
universities (local and abroad) and conducting National Slope Master Plan studies; the Forensic
Unit,responsible for landslide investigation and preparing standards and guidelines for slope
design, and finally the Quality, Training and Public Awareness Unit is responsible for training
personnel in JKR and creating public awareness (Abdullah et al. 2007).
Apart from the above, there are also numerous guidelines and regulations available from the
following government authorities and associations related to slope management: -
a) Department of Environment (DOE)
b) Geology and Mineral Department (JMG)
c) Majlis Perbandaran Ampang Jaya and other local authorities such as Penang Local Council
etc.
d) Ministry of Housing and Local Governments (MHLG)
e) Urban and Rural Planning Department (JPBD)
f) The Institution of Engineers Malaysia (IEM)
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Some of these guidelines and regulations are unclear and do not add value to safety, enhance
slope stability and protection, environmental friendliness and sustainability of the slope
engineering projects. These guidelines and regulations should be harmonized and improved
further by developing unified guidelines for good practices in the planning, design, construction,
supervision, maintenance and monitoring of slope engineering projects, as well as ensuring the
safety, environmental friendliness and sustainability of these projects.
5.3 National Slope Master Plan (NSMP)
In view of the slope failure occurrences in recent years, the Malaysian Government instructed
JKR to carry out the NSMP study in May 2004 to be completed by March 2008. The goal of this
study is to provide detailed elements of a comprehensive and effective national policy, strategy
and action plan for reducing losses from landslides on slopes nationwide including activities at
the national, state and local levels, in both the public and private sectors (Abdullah et al. 2007).
The NSMP consisted of 10 key objectives which were translated into 10 components of the
study. The components of the NSMP and the summary of their objectives are as follows:
ii. Policies and institutional framework - improve policies and institutional frameworks
iii. Hazard mapping and assessments – develop a plan for mapping and assessing landslide
hazards and also develop standards and guidelines for landslide hazard mapping
iv. Early warning and real-time monitoring system- to develop a national landslide hazard
monitoring, prediction and early warning system
v. Loss assessment – assess the current data on landslide losses and develop a national plan for
compilation, maintenance and evaluation of data from landslides
vi. Information collection, interpretation, dissemination, and archiving – evaluate the state-ofthe-
art technologies and methodologies for the dissemination and archiving of technical
information
vii. Training - develop training programs for personnel involved in landslides
viii. Public awareness and education – evaluate and develop education programs related to the
predictive understanding of landslides
ix. Loss reduction measures – evaluate and develop effective planning, design, construction and
maintenance with a view to landslide hazard reduction
x. Emergency preparedness, response and recovery – develop a national plan for a coordinated
landslide rapid response capability.
xi. Research and development - develop a predictive understanding of landslide processes,
thresholds and triggering mechanisms
The NSMP is to be implemented in 3 phases: the first phase is called the short term which would
cover the first 5 years; the second phase is known as the medium term i.e. the period of
implementation between 5 and 10 years; and final phase is known as the long term, which is the
period of implementation of 10 to 15 years and beyond.
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5.4 Undergraduates in Slope Engineering
Apart from improving the understanding of practitioners and policy implementation by the
government on slope engineering and management, emphasis should also be given to how to
improve undergraduates’ understanding on slope engineering fundamentals, which is currently
lacking, and this is one of the most important components to improve slope engineering.
Consequently, universities and colleges should review and update the undergraduate syllabus
from time to time with the assistance of active experienced practitioners to ensure graduates
possess enough fundamentals to suit industry needs.
Besides, structured modules of lecture notes on slope engineering and management should be
developed and updated regularly by pooling resources from a group of universities, colleges and
passionate practitioners to ease the workload of the lecturers so that the quality of the lecture
notes is assured.
Lecturers should also obtain more exposure on slope engineering with the help of practitioners
and getting them to give lectures related to mitigation and prevention of slope failures.
6. CONCLUSION
This keynote presents a brief review on six major landslides in Malaysia that includes old and
new slope failures. Most of the landslides were induced by high rainfall and 80% of the
landslides were caused by man-made factors (design errors and construction errors). Some good
design and construction practices were put forward for slope engineering on planning, analysis
and design aspects, construction control aspects and slope maintenance aspects. Finally, this
keynote also discussed some suggestions on improvement for practitioners, undergraduates,
public sector and implementation of government policy. Practitioners should be equipped with
R&D skills to improve construction industry’s competitiveness and be prepared for globalisation.
