Progress was dramatically halted on the evening of 30 June 2005 when part of the tunnel structure collapsed on to the line underneath, miraculously without a train being involved. The story of the recovery from the collapse is told at this link
The story starts in 1999 when preliminary drillings took place all over the area involved but I have photographs from 1988 which provide a good then-and-now comparison.
Not only did the Tesco project make changes to the station area but before that the layout was simplified. By the start of the project in 1999, the semaphore signals had gone together with the signalbox, and the Up line had been slewed to join what had been the Down through line, leaving just two tracks through the station. These changes made for a much faster layout which suited the increasing number of Chiltern Railways trains running through non-stop and also provided more car parking space.
But the presence of the Tesco project is also apparent in
the 2008 view. In the distance, the turn-back siding
added, with its associated crossover, at the same time as
the other track changes, has been extended to form a
siding for trains bringing in 1000 tonnes of fill
material. The conveyor belt system to bring the fill
material to the site is on the right of the car park, and
the cutting has lost a lot of trees. All the space
behind the Up platform has been raised to form an entrance
to the Tesco site from Station Approach and to provide
working space, entirely covering the garden that had been
created on the site of the old Up platform line and the Up
platform.
To put these two collages in place, here is a plan of the
Tesco site.
We have been looking west from, first, Marsham Lane and
then from Packhorse Road.
In 1999 there was exploratory drilling going on all over the site, including the area to be used for the infill siding.
These pictures contrast the scene from Bull Lane
bridge. There had been a siding here in the early
days of the railway so the ground was likely to be
suitable. The 2005 scene shows a train of 1000
tonnes of scalpings, topped and tailed by the usual Class
66 locos, although 60s, 59s and 47s were seen.
The
trains were a tight fit in the extended turn-back
siding. They were unloaded by a grab onto the
track used by the grabs, and transferred by the other
grab from the track to the conveyor belt hopper - in
this picture the latter grab is in the distance but
not working as evidenced by the empty conveyor belt.
Two trains a day was the usual level of
activity. Next is a view of an arriving train
snaking over the crossover and into the siding.
The trailing loco was usually being dragged
without any crew.
Click on the thumbnails to see larger images.
Now we can turn to the tunnel contruction
project, starting with 1999 - 2008 contrast.
Tunnel construction started in 2004 with the creation of bases for the tunnel segments.
A very large crawler crane was delivered and assembled, here waiting for the first tunnel segments to be delivered. The continuous base for the segments is to the left of the crane.
This is October 2004 and the first segments have been placed overnight, with the next batch lying on the ground close to the crane. This was Sunday 10 October and the contractors had a Possession for the whole day.
Many of the segments have now been placed by the crane into the waiting grooves to the north and south of the railway and the pairs pressed together at the crown. Each segment weighs about 22 tonnes and is a metre wide. At this stage very little fill material had been placed.
Looking from PHRB, fill material is being placed on the north side and some is being shifted by this temporary conveyor to the south side.
On a snowy day, work continues, but now there is sufficient support for the sides of the tunnel arches to allow larger quantities to be moved from north to south. The structure in the foreground will form the stitching beam that attaches each segment to its neighbour on the same side.
Later in February, much more fill can be moved.
The segments are covered in waterproof layers. Here the tunnel is quite close to Marsham Lane and the huge crane has gone, to be replaced by a smaller one later.
The final southside tunnel bases are being built on the deep piled foundations.
A smaller crane is now lifting the last few segments into place near Marsham Lane in the early hours of the morning.
Almost the last segment to be placed is eased into position at around 3 a.m. on 9 June 2005.
Text and pictures, © Guy Gorton 2008
Constrained to 1024 width, no other changes October 2014.