On a day in which intense lightning strikes have crippled Yorkshire's railways, Network Rail has been ordered to resolve serious issues with its timetable planning which has contributed to major disruption.
An investigation by rail regulator the Office of Rail and Road (ORR) discovered "systemic failings" in the Government-owned company's management of rescheduling timetables.
-> Train lines blocked after lightning strike causes disruption
Network Rail must provide a report to the ORR by the end of next month to demonstrate how it is running an "efficient, fair, effective and transparent process" in revising the next timetable in December.
The company was also told to revise its plan to agree timetables 12 weeks in advance, strengthen its resources for creating timetables and speed up decisions on structural reform.
The ORR opened the investigation in February after it emerged the publication of timetables was being delayed.
Chaos ensued after a major timetable change on May 20. Passengers in the north and south-east of England suffered delays and cancellations for several weeks.
A series of failures have been blamed in addition to Network Rail's timetabling, including delayed electrification projects in the North, poor planning by train operators and the decision by transport ministers to phase in the introduction of new Govia Thameslink Railway services.
Transport Secretary Chris Grayling set up a wider inquiry by the ORR on June 4 into what went wrong.
ORR director of railway markets and economics John Larkinson said Network Rail's failings in the run up to May 20 led to "massive disruption, uncertainty and inconvenience to passengers".
He went on: "Network Rail has acted to bring the industry together to address timetabling issues but more and faster change is needed to provide assurance to passengers. That is why we have set out these actions designed to improve capability within Network Rail."
Jo Kaye, a managing director at Network Rail, said it accepted the findings of the ORR investigation into why all timetables are not being finalised 12 weeks in advance.
She added: "It's clear from the ORR's investigation that the issues with timetabling go much further than Network Rail, and we welcome and look forward to the industry-wide inquiry.
"We remain truly sorry for the part we played in the process that caused disruption for so many people and we have learned lessons to make sure it is not repeated."
David Sidebottom, director of watchdog Transport Focus, said passengers want timetables "finalised in good time" so they can plan their trips with confidence.