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Fastening System Upgrade: Mitigating Stray Current Corrosion

To mitigate the persistent issue of stray current corrosion—a critical concern in metro
systems utilizing third-rail traction—KMRL undertook a strategic retrofitting initiative,

replacing conventional rail fastenings with advanced 336iw fastening systems. These

upgraded fastenings feature high-performance insulators and an optimised geometric
design, significantly improving the electrical insulation between the running rails and

the viaduct structure. By minimising electrical leakage, the new fastenings effectively
reduce stray currents, which are known to accelerate electrochemical corrosion in

metallic reinforcement and structural components. This intervention not only
safeguards the longevity of the rails and viaducts but also enhances the overall

durability of the metro infrastructure. The retrofit aligns with KMRL’s capability to

preventive maintenance and system resilience, ensuring sustainable operations while
mitigating long-term degradation risks associated with electrified rail networks.

Automatic Rail Lubrication: Reducing Wear and Noise on Curves

To actively mitigate wear on sharp curves and address persistent challenges related
to vibration and rail noise, KMRL has implemented automatic rail lubrication systems

at critical locations, particularly on curves with a radius of less than 190 meters—
where friction and lateral forces are most pronounced. These systems apply a

controlled layer of lubricant between the rail and wheel flanges, significantly reducing

metal-to-metal contact and associated wear. Advantageously, the lubrication units are
integrated with platform-level emergency switches, enabling station controllers to

manually override the system if necessary, ensuring both operational flexibility and

safety. The results have been substantial: a marked decrease in rail-wheel friction,
leading to smoother train movements, reduced noise levels, and enhanced passenger

comfort. Additionally, by minimising excessive wear, the lubrication systems
contribute to the longevity of tracks and wheels, lowering maintenance costs and

extending the service life of rolling stock

KMRL’s track maintenance framework demonstrates a well-planned blend of

engineering precision, economic outsourcing, and timely innovation. By retaining
control over core safety functions and outsourcing routine activities, the organization

ensures both efficiency and reliability. As the metro network continues to expand, this
proactive and structured method sets a benchmark for track maintenance.