Rail services serving Heathrow are disrupted following a burst water main, while planned engineering work also affects Tube access to the airport. One outlet reports that Heathrow Express and the Elizabeth line see no service for much of the morning, leaving passengers without direct rail options during that period. It also says the Piccadilly line is cut off from Heathrow due to planned engineering work, which stops customers using the Tube for airport journeys. The combined disruptions affect how people reach the terminal, with travellers potentially needing alternative routes or services depending on which rail line they use. The reports describe the situation as impacting airport rail connections during the morning, with service changes tied to both the water main issue and pre-scheduled engineering activity. Details on restoration times or the full scope of the outage are not included in the provided extracts.