London’s transport authority said Sunday it is preparing for around 1 million people to visit the British capital Monday for Queen Elizabeth II’s state funeral.

Transport for London chief Andy Byford said the capital has seen “huge numbers of additional passengers” since the queen died on Sept. 8. But he said demand will “reach a climax” on Monday.

Across the country some 250 extra train services will run, including some overnight trains. Peter Hendy, chairman of Network Rail, said Monday will see the “biggest public transport operation since the London 2012 Olympic and Paralympic Games.”

More than 100 Heathrow Airport flights will be canceled to prevent aircraft noise disturbing the funeral at Westminster Abbey Monday morning and the queen’s committal service at Windsor Castle afterward.

The west London airport said 15% of its 1,200 flights due to take off or land on Monday will be disrupted.