Network Rail has begun a major signalling and power upgrade on the central #London #Thameslink route to improve reliability. The "core" section between London St Pancras International and Blackfriars is one of the UK’s busiest rail links, meaning minor faults often cause widespread disruption.

Engineers are installing a backup "dual detection" train monitoring system between Blackfriars and Farringdon, combining existing track circuits with new axle counters. This ensures trains can keep moving if one system fails. Additionally, the 20MW electrical substation between City Thameslink and Blackfriars—the largest on the 750V third-rail network—is being replaced, and thermal imaging cameras are being fitted to trains to spot faults early.

The project requires weekend track closures on 13–14 and 20–21 June, with services suspended through central London. Testing takes place this autumn ahead of full commissioning by the end of 2026.
https://www.mynewsdesk.com/uk/gtr/pressreleases/major-upgrade-to-improve-reliability-for-passengers-under-way-on-thameslink-route-through-central-london-3452728