Govia Thameslink Railway (GTR) and Network Rail "broke all the rules" when pushing through the new rail timetable in May, leading industry expert Chris Gibb has said.
Gibb, who wrote a report into the Southern meltdown last year, told the Transport Committee that train operator GTR and Network Rail "knowingly broke all the rules" with the new timetable, billed as the biggest shakeup in decades.
GTR, which runs the Thameslink, Southern, Gatwick Express and Great Northern services, introduced a new timetable on 20 May that was designed to increase passenger capacity by 40,000 people and the number of trains per hour.
It soon became clear that the new timetable had failed, with train drivers not given enough time to familiarise themselves with new routes, leading to widespread delays and cancellations.
Gibb, who chairs the industry readiness board that is made up of Network Rail, the rail regulator and the train operating companies, said: "I think we knowingly broke the rules quite a number of times, but we did so in a detailed knowledge of the process and people agreed to break the rues and adopt a different process," he said.
Gibb said the timetable had gone through several cycles. The first plan to deliver 20 trains an hour from May and December this year was deemed to be too ambitious for the industry readiness board, which then recommended to GTR that it was done in eight stages between January 2018 and December 2019, which is the scheme that was accepted by the Department for Transport (DfT) and is currently in operation.
"With the benefit of hindsight that was a challenging thing to commit to, but nobody said the system couldn't cope with this. Nobody said we were being a bit heroic," he said.
Gibb also said the DfT took too long to switch from the first approach to the more phased-in approach. He said the decision was made on 17 November last year – "far later than it should have been".
The delayed decision by the DfT meant the operators did not have the usual 40-week period to phase in the changes, which meant the changes that were due in January were "massive rather than simple ones", he said.
Gibb's evidence to the committee comes as the rail industry releases its revised plans for the December timetable following the May disruption, saying it will make fewer changes to ensure people get a more reliable service.
The industry said it was taking a "cautious approach" to the December timetable and that it would be on a much smaller scale comparable with previous years.
The majority of operators will introduce a new December timetable, while others will continue with their May timetable, including GTR and Northern.