UK rail operator Chiltern Railways has announced a £250m ($407m) upgrade plan that could cut rail travel times between London, Oxford and Birmingham.

The plan involves upgrading over 50 miles of track to 100mph and building a new main line from London Marylebone station to Oxfordshire.

The work is expected to reduce travel times along the busy M40 corridor, cutting Birmingham Moor Street-London Marylebone time by over 20% to 1 hour 40 minutes and Banbury-Bicester time to less than an hour.

The plan includes linking Oxford to the Chiltern mainline by a new rail stretch to be built at Bicester, which would allow new direct passenger services to operate between Oxford and London Marylebone.

The London-Birmingham upgrades are expected to finish by May 2011 and Oxford work is expected to finish by 2013.

Network Rail will fund the project, which will later on be paid back by Chiltern Railways.

The operator is delivering the upgrades in return for securing a 7.5-year extension to its 12.5-year franchise by the government.