Tom Anderson wrote:

I know nothing about Chiltern's market, but do they think they'll be
able to pull in more passengers once this is done?

The December timetable change was the first to take advantage of completion
of the new works under Project Evergreen Phase 2 (two additional platforms
at Marylebone, plus a stabling siding to replace those being lost;
relocation of servicing facilities from adjacent to Marylebone to the new
light maintenance depot at Wembley; shortened signalling sections and
additional signalling and changes from two-aspect to three-aspect and from
three-aspect to four-aspect at various points along the route, particularly
between High Wycombe and Bicester and between Princes Risborough and
Aylesbury) but there are some tweaks to that timetable, in the light of
operating experience, being introduced next week with the summer timetable.

The changes give additional capacity at Marylebone, meaning that trains can
be at the platform for longer (eliminating many of the short turnarounds
that were annoying passengers, by only giving them five minutes or more to
sprint from the concourse to the train) and that more platforms are
available to handle trains when things go awry. The additional signalling
means that trains can run closer together, thus allowing additional trains
to be run. On many services this was becoming necessary due to the booming
number of passengers - but the infrastructure was not in place to allow
additional trains to run. From projected figures this was looking to become
a problem and Chiltern Railways, John Laing and Network Rail acted
proactively to provide the capacity - unlike in several other areas of the
country where pricing passengers away seems to be the accepted action.

At the Network SouthEast launch of the modernised Chiltern network in 1990
the line was operating a total of 89 passenger vehicles (28 two-car trains
and 11 three-car). By privatisation this had been reduced to 75 vehicles by
the transfer of 7 two-car trains to Thames Trains. Since privatisation the
transferred-out trains have returned and an additional 68 vehicles have been
added to the fleet (10 four-car trains, 9 three-car trains and the
single-car used on the peak hour services between Princes Risborough and
Aylesbury). Services have been extended on from Banbury, the former limit of
services (one train every two hours) to serve Birmingham (one train every
half-hour), Kidderminster (peak hours only) and Stratford-upon-Avon.
Passenger numbers have risen significantly over the years and show no signs
of abating, hence the need for Project Evergreen.