West end of the Tesco Tunnel
Gerrards Cross
2005/6
A part of Guy Gorton's website


A complex part of the project was continuation of the new tunnel through the arch of Packhorse Road bridge with the eventual transfer of the load of the road to the new structure beneath.  Work on this part of the job started in January 2005 but was not complete when the middle section of the tunnel collapsed on June 30, 2005.  However, after a pause during the early part of the clear-up after the collapse, the task started up again as recorded here.

 
A platform was built over the tracks in January 2005, reaching back to the west end of the tunnel segments, right through the bridge arch and out some metres over the station end of the railway.  This allowed work within the arch without a Possession.
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This picture is useful because it shows quite clearly how the new tunnel arch profile matches the bridge piers.  Later, we will see how the segments manufactured to match the profile of the new tunnel fit in under the bridge.

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Looking down over the parapet on the east side of Packhorse Road, the platform, still without its decking, reaches the tunnel segments.  The connecting steel wires already cast into the segments are visible, as is some foundation work to the left.  The transition framework will be built here.

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About a month later, work continues on the transition structure.

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Another month and the transition structure, this time at the south side of the tunnel, is taking shape.

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Meanwhile at the west side of Packhorse Road bridge, the new structure takes shape in May 2005.  The platform has fences round it, intensive steel reinforcing is partially in place.  A similar structure will appear against the south pier soon afterwards.  Note the working scaffold under the north arch of the bridge in the foreground - this is being used during the punching of large holes through the bridge pier.

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A few days later, enough clutter has been removed to allow a picture of the hole that has been cut through the pier.  This will be filled with reinforcing steel and concrete.

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At the end of May 2005, the reinforcing by the south arch is taking shape, including some through the hole cut in the pier.

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Early June and the shuttering is erected by the south arch ready for concrete pouring.

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On the same day, the shuttering on the north side is not so far advanced.  This view may help to place the new structure in the context of the old bridge behind it.

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The concrete is in place at the south pillar, but the principal interest is that the picture was taken the day before the tunnel collapsed - at 17:06:40 on 29 June 2005 to be precise.

The date of the next picture is not until August 4, but work on the Packhorse Road bridge structure had been proceeding without being very noticeable and with very little photography - the drama of the collapse aftermath was still in full swing.

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A crane has been brought in to lift the segments that will fit under the road bridge.  Note that the segment is in one piece, not two as in the main length of the tunnel.

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A segment is being lowered, with its temporary feet, on to a temporary set of rails.  This view displays several items that have been worked on whilst collapse clearance was going on simultaneously - shuttering round the concrete has gone, temporary rails in place, the work area cleared of clutter.

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Peering over the east side of the bridge parapet again, two of the new segments are visible to the left and the completed support structure which we saw earlier is on the right.

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It is August 8 and here we can see the new tunnel segments butted up against the earliest ones placed in this project which are now largely cleared of fill material.  The suspended Tesco shed structure and its rather nice shadow is on the right.

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And on the station side of the bridge, the newly place segments match the supporting structure very neatly.

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On the day the railway reopened, August 20, 2005, this is how the supporting structure for the tunnel segments through the old bridge looked.
A quite handsome structure, but if the project ever goes to completion I think it will be buried and invisible.  Ignore the strange image on the right - it is a mirror.

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Finally, this is how it looks now in June 2006.  What will it look like in June 2007?

You may return to the west portal story here.

Pictures and text © Guy Gorton 2006