Holidaymakers travelling to Heathrow were facing severe disruption on Friday due to a train derailment that crippled public transport between central London and the airport.
The incident severely affected rail services and stretches of the Elizabeth line to the west of the capital.
A freight train derailed between Reading and London Paddington, near west Ealing.
Great Western Railway, Elizabeth line and Heathrow Express services were all affected.
There were severe delays on the Elizabeth line between Paddington and Reading/Heathrow Airport.
Rail passengers were also warned of cancellations and delays of up to 25 minutes.
A Network Rail spokesperson said: “At around 6.10am this morning, a freight train derailed while travelling into the sidings at west Ealing.
“There were no injuries and we closed the adjacent lines to assess that it was safe for trains to pass.
“One of the lines has now reopened to passenger trains and a team is on site to assess the situation with the freight train and whether the second adjacent line can be safely reopened.
“Trains between London Paddington and Reading may be cancelled, delayed or revised while we deal with the incident.
“Passengers are advised to check their journey with National Rail Enquiries before travelling.”
Great Western Railway warned on its website that some lines were blocked, with disruption expected up to midday.
Meanwhile, an overtime ban by the Aslef union at 16 companies is continuing until Saturday, causing more disruption to services.
On Saturday train drivers will walk out at Chiltern Railways, Great Western Railway, LNER, Heathrow Express, Northern and TransPennine Express.
A strike on Monday will affect c2c, Gatwick Express, Greater Anglia (including Stansted Express), Great Northern, Southeastern, Southern, South Western Railway (including the Island Line) and Thameslink.
The Easter holiday is one of the busiest times of the year for Heathrow.
Dubai, Turkey and the Canary Islands were among the most popular destinations as two million British holidaymakers travelled abroad last weekend.
In February, Heathrow announced it had returned to profit for the first time since the Covid pandemic devastated global air travel.
The consortium that owns Heathrow, FGP Topco, said it made £38 million in pre-tax profits last year, the first time the airport has been back in the black since 2019, following a loss of £684 million in 2022.
The fightback to profit was mostly down to the 79.2 million passengers, representing a 28.6 per cent increase on the year before, that passed through Heathrow last year.
The airport celebrated the end of last year with its busiest-ever December.
