Delhi Metro Rail Corporation will replace 33-kilovolt copper cables with aluminium across 175 kilometres of its network to reduce theft and improve service reliability. The project is estimated at Rs 325.9 million (mn) and is expected to be completed over 18 months. The corporation plans to remove existing copper cables and install aluminium wiring in a trefoil formation along elevated viaducts. The move follows a sharp rise in thefts that exploit copper's high resale value in scrap markets. Officials have concluded that aluminium has a significantly lower scrap value and will therefore be less attractive to thieves. The overhaul will focus on the most theft-prone and operationally sensitive stretches, including sections near the Yamuna Bank line along the riverbed, the Airport Express Line, and parts of the Pink Line near Seelampur and Welcome stations. As per the DMRC, in 2025 there were 89 reported cases of cable theft, of which 32 involved signalling cables and 22 related to electrical wiring. One of the most severe incidents occurred in March last year between Seelampur and Welcome when signalling cables were stolen and train movements were severely impacted. Trains were forced to slow to 25 kmph between Mansarovar Park and Seelampur on one occasion, creating cascading delays across the Red Line and affecting commuters throughout the day. More recently, on January 11 a cut of nearly 800 metres of signalling cable on the Airport Express Line between Dhaula Kuan and Shivaji Stadium led to restricted speeds on the up line towards New Delhi. The cut cable pieces were later found near a metro pillar during inspection and repairs are complicated by the fact that trains run at intervals of three to five minutes. The corporation has previously implemented preventive measures such as cementing cables in vulnerable areas, installing anti-theft clamps, using concertina coils, covering cable trays, and exploring drone and CCTV surveillance, but thefts continued. By switching to aluminium the DMRC aims to deter theft and reduce operational disruptions, sources said. The replacement programme will be rolled out in phases, prioritising stretches with recurring incidents to minimise disruption during implementation.