Tube passengers on part of the Northern line say they are having to wait up to 41 minutes for a rush-hour train.
Commuters who rely on the Mill Hill East branch of the line have expressed their frustration at the scale of recent delays and train cancellations.
A survey of more than 500 trains between May 9 and June 2 found that 42 per cent were delayed, 40 per cent ran on time - and 41 trains never ran at all.
Even more frustratingly for passengers, some trains depart ahead of schedule – leaving those who arrive at the station on time with an even longer wait until the next service.
Jay Hostan, a software engineer who works at Selfridges, monitored the morning and evening service over a 15-day period at Mill Hill East.
He said there was “daily chaos” during the rush hour – despite “PR spin” from Transport for London of a good service.
However he said the latest figures were slightly better than those recorded in the previous fortnight.
In a post on LinkedIn, he said: “Commuters waiting 20 to 40 minutes daily for a train during peak hours is not a minor issue. It is systemic failure.”
A fellow commuter, Graham White, who works for BBC Radio, said he also suffered problems on a daily basis trying to get to central London.
“At its worst it’s taken me 90 minutes to get from W1 to my front door, a journey that should be an average of 50 minutes, and waits of up to half an hour to leave Mill Hill East are far too common.”
Problems with a lack of capacity to stable trains at depots are said to be a factor. The majority of trains on the Northern line’s High Barnet branch bypass Mill Hill East, which is effectively a branch line between Finchley Central and West Finchley stations.
Some passengers say they are forced to take a taxi to Finchley Central. Others say the delays, coupled with an increase in residents around Mill Hill East, results in packed trains.
The survey found that of 258 trains scheduled to depart in the morning, 33 did not turn up.
There was an average gap between southbound trains of 22.3 minutes on weekday mornings.
Summarising the findings, Mr Hostan wrote: “This is not a case of isolated events; the service repeatedly fails during the most critical morning commute window.
“This performance level is incompatible with advertised service reliability claims (e.g. 95%+ operational reliability).
“Actual real-world data exposes chronic operational failures far beyond any random variance.
“Consecutive no-shows and extended gaps of up to 41 minutes were recorded during peak hours.
“The high proportion of no-shows, excessive delays, early departures, and wide service gaps directly impact passengers’ ability to rely on advertised schedules, particularly during peak morning commute hours, where the failure rate is highest.”
The findings have been shared with Dan Tomlinson, the Labour MP for Chipping Barnet.
He told The Standard: "Residents using Mill Hill East station deserve better. The delays, no shows, and huge gaps in services during peak times are unacceptable, and I have been supporting residents who have gathered this data.
"Anne Clarke, the London Assembly member for Barnet and Camden, and I have raised this with senior staff at TfL repeatedly, and I have been assured they are investigating what changes and improvements can be made. I will not stop until improvements have been secured."
TfL has been approached for comment.
