The second part of the project upgraded the line to running on more of track, with junctions at Neasden, Northolt and Aynho rebuilt to permit higher speeds. The 'up' through track was restored at Princes Risborough and signalled for bidirectional use, the existing 'up' line becoming a bidirectional platform loop. A new turnback siding was provided at Gerrards Cross and a new 'down' through track built from Northolt Junction to Ruislip Gardens, running alongside the 'up' line to the east of the waste transfer station; the 'down' line will continue to serve South Ruislip. Speed restrictions through Bicester North were raised to permit running, with a new 'up' alignment and platform. Two of the original terminal platforms at Birmingham Moor Street were reopened for Chiltern services in December 2010. Accelerated services started in September 2011, after being postponed due to concerns about whether the works would be completed in time.