It’s just over one year since I last had a detailed look at the worksite for the forthcoming Colne Valley Viaduct, and I was back last week to see what’s changed.
Launch Girder
The viaduct is being built north to south, and this striking red structure, the launch girder, has just been assembled on the earthworks leading to the northern end. It will soon take a slow journey, sliding the couple of miles across the viaduct, atop the newly created piers, building the main bridge deck from the precast sections being created at an onsite factory.
Piers
These are now appearing regularly, in various stages of completeness stretching along the first part of the viaduct. The plan I believe is to create one a week.
The pair either side of the A412 (Nos. 3 and 4) have a different design, as they are angled, to support the viaduct which will cross the road here at a severe skew angle.
Grand Union Canal
The Grand Union Canal is one crossing that needs to stay open as much as possible – so the haul road will not cross it. Instead, two haul roads will meet either side of it. Here, the photo shows the southern limit of the northern haul road pontoon on Savay Lake, with the forthcoming piers of the viaduct due to appear on the left.
Reflectors for a survey robot have been embedded beside the canal here on its towpath here, at the point that viaduct will cross, to check there’s no movement or subsidence of the canal or towpath here when the piers or viaduct deck go on – particularly important as the land and lake to the west of the towpath is slightly below the canal level.
Haul Road Pontoon
On the other side of the canal, another haul road pontoon, coming across Broadwater Lake from the south and London. It may advance a little bit more, across the track and cycle route here, and up to the other side of the Grand Union Canal. The viaduct piers will be on the right. It will likely be over a year before these ones get constructed, as this is the southern end of the viaduct. The closed, but not yet relocated, Hillingdon Outdoor Activity Centre, is just to the right of the far end of the pontoon here – spared a direct hit by a late design change in the HS2 route, but still likely to move to be on a different lake.
