Chiltern services disrupted into evening as track safety checks hit Marylebone routes

Passengers travelling to and from London Marylebone are facing delays and cancellations this evening after safety inspections of the track were ordered in two separate locations, according to [2]. The line towards Marylebone between West Ruislip and South Ruislip is currently blocked while an inspection takes place, National Rail said, according to [2]. Chiltern Railways passengers have been told to expect disruption until the end of the day, with services between West Ruislip and Marylebone liable to be cancelled or delayed by up to 45 minutes, according to [2]. A second inspection is under way between the Bicester area and Haddenham & Thame Parkway. A Chiltern Railways spokesperson said services on the lines towards Oxford, London and the West Midlands may be cancelled or delayed as a result, according to [2]. Between them, the two inspections are affecting a wide swathe of the Chiltern network. Routes hit include those between London Marylebone and West Ruislip, High Wycombe, Aylesbury, Aylesbury Parkway, Oxford, Birmingham Moor Street and Birmingham Snow Hill, as well as services to Stourbridge Junction, Stratford-upon-Avon and Banbury, according to [2]. Passengers are advised to check the latest information for their service before travelling and to allow additional time for their journeys, National Rail said, according to [2]. The inspections come after two passenger trains derailed just outside London within 24 hours of each other last Thursday and Friday, as temperatures climbed above 38C during the fifth heatwave of the summer, according to [2]. Extreme heat is known to cause steel rails to expand and sometimes buckle, according to [2]. The Rail Accident Investigation Branch and Network Rail have launched investigations to establish what caused the two derailments, according to [2]. Separately, an earlier fault with the signalling system between Rickmansworth and London Marylebone, which had caused disruption on the same Chiltern route, has now ended, according to [1]. That incident affected services between Aylesbury Vale Parkway/Aylesbury and Marylebone, according to [1], and appears to be a distinct, now-resolved problem rather than part of this evening's track inspections. Neither source gives a time by which the West Ruislip or Bicester–Haddenham inspections are expected to conclude; Chiltern's guidance is simply that disruption should be expected "until the end of the day," according to [2]. What caused the derailments, and whether the current inspections are precautionary or tied to specific defects found on the line, is not established in the material reviewed. What to watch next: whether RAIB or Network Rail publish any findings linking the heatwave-era derailments to today's safety inspections, and whether Chiltern confirms a time for services to return to normal.