The Crossrail constructed TfL Elizabeth Line has been dogged by setbacks.
Work began in 2009 and it was originally scheduled for completion in December 2018.
However, following a series of delays and additional costs, it is still a work in progress.
On Thursday, Alison Moore, chairwoman of the London Assembly Transport Committee said: “It is vital they adopt a Sherlock-style forensic focus to make sure no aspect of delivering the project on time and on budget is missed.
“Londoners need assurance they will be no further out of pocket and the train will be on the track by summer next year.”
The committee is losing patience with Crossrail, the company responsible for bringing the line into fruition.
Their latest reason for not delivering on time is the logistical fallout of COVID-19.
Andy Byford, London’s transport commissioner, said: “The coronavirus pandemic has obviously had some impact on the project and ways of working, and Crossrail has responded to this by ensuring sites remain a safe place to work.
“We will of course continue to ensure the London Assembly is fully updated on progress of the Elizabeth Line, which is so vital for London and beyond.”
The government loaned the railway £825million in December, with the overall cost now reaching £18.25billion.
This is a huge overspend, especially when you consider the original budget was only £14.8billion.
The plan is to build a tube train link between Paddington Station and Stratford, running through central London.
This will form a connection between the Great Western and Great Eastern Main Lines, which terminate at opposite ends of the capital.
Existing stations like Liverpool Street and Canary Wharf will form part of the route.
The finished product is forecast to cut journey times and create greater capacity, whilst being fully accessible.
To many people though, until it opens to the public, the Elizabeth Line will be considered a white elephant.