What is Central Spine Road?

The Central Spine Road (CSR) is a federal-government road project under the Ministry of Works (KKR) crossing the interior of Peninsular Malaysia, traversing the Titiwangsa mountain range across Pahang state to improve connectivity between the East Coast and West Coast through the central highlands. The corridor runs through hill-station-altitude terrain with steep cut slopes, monsoon-recharged groundwater, and class III-IV slope-engineering classification per JKR Slope Engineering Manual.

What was Infraconcrete's scope on Central Spine Road?

65,000 m² of slope face stabilised using six integrated specialist systems delivered in-house: soil nailing, guniting / shotcrete, rock bolting, rockfall barriers, retaining walls, and horizontal drains. The integrated nature of the works (single contractor delivering all six systems on overlapping work zones) was specifically what allowed the integrated design intent to be executed without inter-vendor coordination drift.

What were the engineering challenges?

1) Hill-station altitude terrain with steep cut geometry (face angles 60 to 75 degrees, face heights up to 30 m). 2) Class III-IV slope classification per JKR with associated factor-of-safety and design-life requirements. 3) Monsoon-recharged groundwater regimes with intermittent natural springs and weathered-rock joint flow. 4) Remote alignment with restricted material logistics. 5) Integrated multi-system design intent: every section combined at least two of the six specialist systems.

Why six integrated systems on the same corridor?

Slope geometry, ground conditions, groundwater regime, and rockfall hazard varied along the alignment. Some sections were soil-nail + shotcrete + drainage combinations. Others were rock-bolt + mesh + rockfall barrier where exposed rock was the controlling failure mode. Tall retaining walls were used at fill embankments and bridge approaches. Horizontal drains addressed monsoon-recharge zones. No single system addressed all conditions; the integrated approach delivered six systems as one coherent slope-engineering response across the corridor.

Why was Infraconcrete selected for KKR project?

CIDB G7 (highest grade), federal-panel registration with KKR (Ministry of Works), demonstrated EKVE federal-expressway track record, six in-house specialist systems (no subcontracting on geotechnical scope), and the proven ability to execute integrated multi-system slope works on a single corridor without inter-vendor handoff. Single-team accountability across the full slope-engineering toolkit suited the integrated design intent of the CSR alignment.

Federal Project Case Study · Ministry of Works (KKR)

Central Spine Road: 65,000 m² of mountain-corridor slope integrated across six systems.

The Central Spine Road (CSR) is a federal-government road project under the Ministry of Works (KKR) crossing the Titiwangsa mountain range through Pahang's interior, improving connectivity between the East and West coasts via the central highlands. Infraconcrete delivered 65,000 m² of slope face stabilised using all six in-house specialist systems integrated across the corridor: soil nailing, guniting / shotcrete, rock bolting, rockfall barriers, retaining walls, and horizontal drains. Hill-station altitude terrain. Class III-IV slope geometry per JKR. Single-contractor delivery on integrated multi-system design intent.

65,000 m²

Slope face stabilised

6 systems

Integrated specialist scope

KKR

Ministry of Works project

CIDB highest grade

01 / Project context

Federal mountain corridor, Pahang interior.

The Central Spine Road (CSR) is a federal-government road project administered by the Ministry of Works (Kementerian Kerja Raya, KKR) that improves connectivity between Peninsular Malaysia's East and West coasts by traversing the Titiwangsa Range through the interior of Pahang state. The corridor runs through hill-station-altitude terrain with steep mountain cut slopes, monsoon-affected groundwater regimes, and exposed weathered-rock faces. Several sections of the alignment cross terrain that would historically have been considered non-buildable without specialist slope-engineering intervention.

The alignment crosses Class III to Class IV slope geometry per the JKR Slope Engineering Manual (steep cut faces, exposed rock with joint sets, elevated factor-of-safety design targets due to consequence of failure at the road centre-line). The alignment is one of the most slope-engineering-intensive federal road projects in recent Malaysian infrastructure, and the integrated multi-system response across the 65,000 m² reflects that.

02 / Engineering challenge

Mountain spine, integrated design intent.

1. Hill-station altitude slope geometry

Cut faces typical 60 to 75 degrees, face heights up to 30 m on multiple sections. Class III-IV slope classification per JKR Slope Engineering Manual, meaning target factor of safety against monsoon-driven failure is set at the higher end of the JKR framework. Composite soil profiles with Grade III-V weathering classification per BS 5930. Cuts exposed both residual soil and weathered rock within the same face on most sections.

2. Monsoon-recharged groundwater

Mountain-altitude rainfall regimes drive substantial groundwater recharge along the central spine. Natural springs and weathered-rock joint flow were observed at multiple chainages during pre-construction site investigation. Without groundwater control, structural reinforcement alone could not achieve target factor of safety against post-construction monsoon failure.

3. Integrated multi-system design intent

Most sections of the alignment required a combination of at least two specialist systems to achieve the design intent. Typical packages: soil nailing + shotcrete + horizontal drainage; rock bolting + mesh + rockfall barrier on exposed-rock sections; retaining walls + drainage on fill-side approaches; integrated multi-system on transition zones where geometry and ground conditions changed along the face.

4. Remote alignment logistics

Mountain-interior alignment with restricted access on several sections. Mobile camp logistics, helicopter-supported supply on the most remote chainages, and self-contained drill rigs deployed per section. Material supply (cement, threadbar, slotted pipe, mesh, shotcrete inputs) staged in advance to match production rates.

5. Single-contractor integration

The integrated design intent (multiple systems per section) made a single specialist contractor the natural delivery model. Multi-subcontractor execution would have introduced inter-vendor handoff at every interface (drilling-to-grouting, grouting-to-mesh, mesh-to-shotcrete, shotcrete-to-drainage). Single-team in-house delivery removed those interfaces.

03 / Scope delivered

Six systems, one corridor.

Soil nailing

Primary reinforcement on weathered-soil cut sections. Y20 to Y32 deformed bar plus self-drilling hollow bar (R32, R38) on mixed-ground zones. Nail length 6 to 12 m, 1.5 to 2.0 m grid, 15 degree inclination, hot-dip galvanised permanent works, DCP on selected aggressive-ground sections.

Guniting / shotcrete

Face protection across soil-nailed and rock-bolted slopes. Wet-mix shotcrete 75 to 150 mm thickness with BRC welded mesh A98 / A142. ACI 506 / BS EN 14487 compliant. Fibre-reinforced shotcrete (E700) at high-deformation sections.

Rock bolting

Exposed-rock cut sections with mapped joint sets. Tensioned and grouted rock anchors, Y25-Y32 bar, 3 to 8 m length, 1.5 m grid. Combined with shotcrete face and rockfall protection where consequence at the road below required active stabilisation.

Rockfall barriers and netting

Energy-rated flexible barriers (500 to 2000 kJ range) and drape mesh / active anchored mesh on rock cuts where loose-block hazard was the controlling failure mode. To ETAG 027 / EAD 340059.

Retaining walls

RC cantilever walls at tight-footprint cut transitions; MSE walls with StrataGrid PET geogrid (supplied via Starwall) at fill-side embankments and bridge-approach abutments. Height range 3 to 12 m typical.

Horizontal drains

Sub-horizontal drains 30 to 60 m length at 3 to 5 degree upward inclination into the slope body, slotted UPVC pipe with geotextile filter sock. Lowering monsoon-driven body groundwater table along the alignment, raising FoS at lower structural cost than reinforcement-only alternatives.

04 / Standards and delivery

KKR / JKR federal-grade.

Design standards: JKR Slope Engineering Manual (the controlling Malaysian document for Class III-IV slopes), JKR Standard Specifications, BS 6031, BS 8006-2, BS EN 14490, BS 8081, BS EN 14487, ACI 506, ETAG 027, FHWA-NHI-14-007, FHWA-RD-97-130, AASHTO LRFD, KKR / Ministry of Works employer specifications.
Federal-grade submittals: design calculations, design drawings, method statement per section, ITP (Inspection and Test Plan), HIRARC, material certificates of conformance, pre-production test panels and pull-out tests, daily drill and grout logs, monthly progress reports to consultant and KKR.
Integrated multi-system coordination: single ITP per section covering all systems present at that chainage, single method statement integrating the trade sequences, single daily site record covering all in-house crews on that section. No inter-vendor handoff documentation needed.
Quality control: mix design records and trial panels for shotcrete, pull-out test records for soil nails and rock bolts, grout cube tests and Marsh cone flow tests daily, flow measurement at drain outlets, BRC mesh placement and shotcrete thickness verified per panel.
As-built documentation: consolidated as-built drawings per section showing all systems installed (nails, bolts, drains, walls, mesh, shotcrete extent), material certificates, complete test record, monitoring readings on instrumented sections.

05 / Outcome

Mountain corridor slope, integrated and delivered.

65,000 m² of mountain-corridor slope face stabilised using six in-house specialist systems integrated across overlapping work zones, delivered under KKR / Ministry of Works federal documentation requirements. The integrated single-contractor approach addressed what would otherwise have been a multi-subcontractor coordination challenge across drilling, grouting, mesh, shotcrete, drainage, rockfall, and retaining trades.

Central Spine Road, alongside EKVE and ECRL Section 3, anchors Infraconcrete's federal-panel track record in the highway / road / ministry-works space. The KKR experience particularly demonstrates the value of single-team integrated delivery on complex multi-system alignments where conventional multi-subcontractor execution would have struggled with interface coordination.

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