Coastal Road Construction - Monopiles-Paper

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The Mumbai Coastal Road Package 1 project is using large-diameter monopile foundations for the first time in India on a bridge in a marine/intertidal setting. The 3.82 km package includes a mainline bridge between Priyadarshini Park and Baroda Palace. Monopiles of 2.5 m and 3.2 m diameter were selected as an alternative to conventional pile groups and pile caps.<br /><br />The approach reduces seabed excavation, temporary cofferdams, construction waste and disturbance to sensitive coastal ecology. Its smaller footprint—about 12–15% of that of a pile group—and elimination of pile-cap construction are expected to shorten foundation work by approximately six months. Keeping the pile–pier connection above mean sea level also improves inspection and maintenance access.<br /><br />Geotechnical investigations, including boreholes and multichannel analysis of surface waves, identified basalt, tuff and related formations. The piles are designed to be socketed into competent rock to a minimum depth of about 1.5 times the pile diameter. Construction proceeds through permanent liner installation, positioning of the drilling rig and bottom-hole assembly, reverse-circulation drilling, bore cleaning, reinforcement-cage placement, and tremie concreting.<br /><br />Pile performance is verified using bidirectional axial static, lateral and dynamic load tests, alongside cross-hole sonic logging. The reported load-test results were within the designer’s acceptable limits. The authors conclude that monopiles provide a faster, more maintainable and environmentally considerate foundation option for marine and intertidal bridges, and that successful implementation on this project may build confidence in wider adoption.

Keywords

Mumbai Coastal Road Package 1

monopile foundations

marine bridge

intertidal setting

large-diameter piles

pile group alternative

seabed excavation reduction

geotechnical investigations

rock socketed piles

load testing