Chiltern Railways’ new summer timetable begins on Sunday 20 May 2018. In the main there are only a few minor changes affecting trains from Bicester. Those changes that have been made are targeted to improve capacity and performance on Mondays to Fridays.
An additional carriage has been added to evening peak trains at 1650, 1718, 1750 and 1950 from Marylebone to Oxford. From 21 May the 1335, 1406 and 1435 trains from Marylebone to Oxford will also have an additional carriage.
A consequence of running longer trains is that the 1928 from Oxford to Marylebone no longer calls at Islip (this train will be formed of 9 carriages instead of 8). However this is now too long for the platform at Islip. So the previous 1902 departure from Oxford is being retimed to 1901 and will pick up the Islip stop instead.
On Friday evenings there will be a new later last train back from Oxford to Marylebone at 2335. It arrives Bicester Village at 2350 and continues to Marylebone arriving 0040 on Saturday morning.
The last train Mondays-Thursdays (and also Fridays previously) departed Oxford at 2315 arriving at Bicester Village 2331 continuing only to High Wycombe.
In the morning peak the 0910 Oxford to Marylebone (Bicester Village depart 0925) no longer calls at Beaconsfield (0957). Instead the 0907 Banbury to Marylebone (Bicester North 0930) will additionally call Beaconsfield at 1003 but then omits Gerrards Cross (1008). The 0822 Birmingham Snow Hill-Marylebone (Bicester North 0943) will now stop at Gerrards Cross at 1016.
Some trains towards London Marylebone may depart one or two minutes later but most will still arrive in London at the same time.
The Bigger Picture
Nationally, the core train timetable changes twice a year, in May and December. Whilst the changes to Chiltern services this summer are minimal, overall the May 2018 timetable change is the largest in living memory, needing the rescheduling of almost four million services – 600% more than normal. From May the first electric trains will run between Preston and Blackpool and there are also big changes to services with new destinations and services both on the Thameslink network through central London and via the new Ordsall chord link in central Manchester. On Thameslink there is a 13% increase in services with new trains.
The scale of the changes this year has meant that the Network Rail timetable planning teams have been unable to deliver the new timetable within the usual timescales.