London Underground passengers face travelling in conditions unfit for animals if investment in the network does not continue, a business group has warned.
London First said commuters could be forced to endure temperatures of 32C - banned under EU regulations for transporting livestock.
A report for the group said any cut in funding would lead to "cattle-class conditions every morning".
It said the number of people commuting in the mornings in conditions equivalent to four or more people in a telephone box would double to half a million by 2026.
"Decades of Underground misery" would follow, the report warns.
The London First study looked at the London Underground by 2026, both with and without upgrades that have been promised since 2003.
Its conclusion paints a dire picture of transport in the capital if funding is withheld.
London's busiest Tube station, Victoria, would have to close every six minutes for safety reasons, it said.
The report also predicts severe congestion on the Piccadilly Line between Finsbury Park and Holborn, on the Northern Line between Camden Town and King's Cross, and on the Bakerloo Line.
London First chief executive Baroness Jo Valentine said: "The Tube is an iconic symbol of bustling London. But in the last 20 years it has risked becoming a worn and broken asset.
"Its modernisation began six years ago. It must not falter, or we risk sentencing Londoners to decades of Underground misery, with cattle-class conditions every morning."
London Mayor Boris Johnson, who joined London First at the launch of the report, said: "This report sets out in graphic terms the absolute necessity to keep investing in London's transport infrastructure.
"The alternative is sardine-tin travel that will do nothing for Londoners' quality of life or our city's reputation."
Send Article by Email
Send Article by IM
Blog This with Y! 360
Printable View
