Train lines are blocked after a points failure between London St Pancras and St Albans this morning.
Services have been forced to reroute between West Hampstead Thameslink and Radlett stations, because of the problem at Cricklewood, and this is causing congestion.
Scheduled trains have therefore been cancelled or delayed by up to an hour and disruption is expected until 12pm.
Passengers can instead use their tickets on Southern, Great Northern, Thameslink, London Underground and London bus routes.
This follows two weeks of commuting hell on the Thameslink services, after new timetable teething problems saw widespread cancellations, disruption, and confusion for both rail passengers and staff.
To follow this recent incident on Twitter use #StAlbans
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