Client & Advisory Mandate

The Tañon Strait, a body of water separating the islands of Negros and Cebu in the Visayas, spans approximately 160 kilometers in length with widths ranging from 5 to 27 kilometers and maximum depths reaching 500 meters . This strategic maritime corridor connects the Visayan Sea in the north to the Bohol Sea in the south, serving as a vital shipping route and an area of exceptional ecological significance .

The proposed fixed link forms part of the broader Iloilo–Guimaras–Negros–Cebu Link Bridge network — a visionary infrastructure program aimed at transforming inter-island connectivity in the Visayas. The complete network comprises three phases: Phase I connecting Panay to Guimaras (approximately 13 kilometers), Phase II linking Guimaras to Negros (approximately 19.47 kilometers), and Phase III spanning the Tañon Strait itself (approximately 8 kilometers) . Collectively, this represents one of the largest infrastructure initiatives in the Philippines, with projected investments reaching PHP 187.54 billion for the Panay-Guimaras-Negros sections alone.

Technical Challenges & Assessment Framework

Our pre-feasibility study addressed a complex interplay of technical, environmental, and operational constraints that define this mega-project:

Seismic Considerations: The Visayas region lies within a zone of moderately high seismic activity. The bridge design must accommodate significant seismic loads while maintaining structural integrity and serviceability. Our assessment incorporated advanced dynamic analysis methodologies to evaluate potential seismic scenarios and their impact on various structural configurations.

Extreme Water Depths: With maximum depths of up to 500 meters in certain sections of the strait , foundation design presents extraordinary challenges. Deep-water construction techniques — including large-diameter drilled shafts, caisson foundations, and potentially floating or semi-submersible support structures — were evaluated for technical feasibility and cost-effectiveness.

Marine Environmental Protection: The Tañon Strait was designated as a Protected Seascape under Presidential Proclamation No. 1234 in 1998, encompassing more than 5,000 square kilometers of marine territory — making it the largest marine protected area in the Philippines . The strait is renowned for its extraordinary marine biodiversity, hosting 14 documented species of whales and dolphins, including the endangered Irrawaddy dolphin, along with resident populations of Indo-Pacific bottlenose dolphins and spinner dolphins . The strait serves as critical breeding, feeding, and resting grounds for these marine mammals . Our study therefore incorporated comprehensive environmental impact assessments to ensure that construction and operational activities would minimize disturbance to these fragile ecosystems.

Scope of Work & Deliverables

GVMEngineering Ltd's pre-feasibility study encompassed the following key components:

Constructability Assessment: Evaluation of construction methodologies appropriate for the challenging marine environment, including balanced cantilever techniques, segmental precast construction, and floating platform deployment. The extreme height and difficult terrain demand innovative construction approaches, drawing from international best practices for deep-water bridge projects.

Capital Expenditure Estimation: Comprehensive cost modeling incorporating foundation engineering, superstructure fabrication, marine logistics, specialized equipment mobilization, and environmental mitigation measures. The analysis considered both conventional and accelerated construction schedules.

Operational Safety Framework: Development of operational protocols addressing vessel collision protection, wind and wave loading, seismic response, and long-term structural health monitoring. The study included risk assessment matrices for catastrophic failure scenarios and emergency response planning.

Marine Traffic Integration: The bridge design must accommodate the strait's function as a busy shipping corridor. Our assessment evaluated navigational clearances, ship collision protection systems, and potential impacts on commercial and fishing vessel operations.

Project Outcomes & Technical Framework

The study provides DPWH with a comprehensive technical framework for strategic mega-project execution. Key deliverables include:

Preliminary Structural Concepts: Evaluation of multiple bridge typologies — including cable-stayed, suspension, and hybrid systems — optimized for the unique site conditions. The preferred conceptual design balances structural efficiency, construction feasibility, and long-term durability.

Phased Implementation Strategy: Recommendations for project packaging and execution sequencing that manage financial exposure while delivering early operational benefits.

Environmental Management Framework: Protocols for marine mammal monitoring, turbidity control, noise mitigation, and habitat protection during construction and operation phases.

Economic Feasibility Analysis: Cost-benefit assessment incorporating travel time savings, logistics efficiency improvements, regional economic development impacts, and tourism sector benefits. The Tañon Strait crossing represents a transformative infrastructure investment for the Philippines — one that will fundamentally reshape inter-island connectivity, stimulate regional economic development, and serve as a testament to Philippine engineering capability. Our pre-feasibility study provides DPWH with the robust technical foundation required to advance this visionary project toward detailed design and eventual construction.

Technical Alternatives

Five Evaluated Crossing Concepts

Five distinct structural solutions were systematically evaluated to cross the challenging marine geology and hydrodynamics of the Tañon Strait.

Option 02

Subsea Bored Tunnel

Parallel Service Tunnel

Floating Bridge (Pontoon)

Drill and blast excavation reinforced with high-pressure jet grouting to traverse fractured deep rock zones under high water pressure.

Dedicated secondary tunnel providing emergency evacuation, pressure relief, continuous ventilation, and maintenance access.

Surface pontoon-type crossing designed for deep water profiles, anchored against strong ocean currents and hydrodynamic loads.

Option 03

Option 04

Option 05

Submerged Floating Tunnel

Deep TBM Tunnel (-350m)

Deep TBM Tunnel (-205m)

Innovative SFT structure suspended below marine navigation depth, anchored securely to the seabed via high-tensile tether cables.

Tunnel Boring Machine alignment operating at -350 meters depth to stay within competent bedrock below the active sea floor.

Optimized TBM profile at -205 meters depth, balancing gentler approach grades with required rock cover and pressure management.

Key Feasibility Parameters

5

crossing options evaluated

-350m

maximum tunnel depth

DPWH

client authority

2 Islands

Negros and Cebu link

GVMEngineeringltd delivers expert technical leadership, feasibility analysis, and structural risk management for complex fixed links.