Chiltern Railways is to delay the launch of its new Chiltern Mainline Service which would allow passengers to travel from Birmingham to London in 90 minutes.
The company said it wanted to reduce the risk of unplanned disruption to passengers, and therefore will not launch the service in May as planned but instead wait until late summer.
It said the decision was following a thorough review of its Evergreen 3 project, which highlighted a risk of overrunning engineering works in May if the works proceeded as planned.
Rather than risk unplanned disruption or late notice timetable changes, the company will move a section of works to utilise the quieter month of August, thereby ensuring passengers are not affected by unexpected disruption in May.
The project to create the Chiltern Mainline began in January and has so far delivered a series of improvements along the route to enable trains to run faster.
These include upgrades to track, a new platform at Bicester North, additional fast track at Princes Risborough, new cross-overs where trains can switch lines at three locations and a new two-track bridge in South Ruislip.
As a result of the changes being made, the closure in April/May and weekend works until May will now be significantly reduced in scope, meaning that fewer days are required in May, and that the works will be less disruptive.
It also means that some weekend closures of the route that would have resulted in no trains to Marylebone will now be scaled back.
There will be a normal service for most weekends during the summer months, with the critical works completed in August, when passenger numbers are at their lowest.
This will be done through a partial closure in late August for commissioning, when the new infrastructure is made ready for use. This needs to take place shortly before the new timetable starts operating in late summer.
Adrian Shooter, chairman of Chiltern Railways, said: “We are obviously disappointed to be postponing the launch of the Chiltern Mainline but do believe it is the right decision for our passengers.
"We are undertaking this project to offer a better service to passengers and are keen for customers to see the benefits of our investment as soon as possible.
"However, we are not comfortable with a risk of our passengers experiencing unplanned disruption and would rather spread the work over a slightly longer period and enable our passengers to plan their journeys with confidence.
"We are sorry that we are not able to offer the improved service from May as planned, but it will be ready when commuters get back from their summer break.”