Colne Valley Viaduct crosses the Grand Union Canal

Just over half-a-mile more of high-speed route structure to assemble as it strides out over historic waterway.

DECK construction work for HS2’s 2.1-mile long Colne Valley Viaduct has just over half-a-mile to go after it reached the point where the structure crosses the Grand Union Canal at the end of March.

By the time of it bridging the waterway near Denham in Buckinghamshire, 1.5 miles of its deck had been completed and 755 of a total of 1000 deck segments had been moved into position, creating 39 spans. Fifty-six piers, all of which have been completed, will support the entire length of the viaduct.

Unlike the canal, which was also an extensive civil engineering effort and covers a similar distance on its way between Birmingham and London, the high-speed route has been designed for a journey time of 49 minutes between the cities.

Across river and road

The Colne Valley Viaduct will also take the route across the River Colne, local roads and a series of lakes. Foundations up to 60 metres (197 feet) deep were built into the lake beds to support concrete piers, which were cast in situ.

The first piles were sunk in early 2021, and a launching girder to lift the segments forming the viaduct arches was brought into use the following spring. Construction work passed the halfway point in November last year.

Align Joint Venture (comprising Bouygues Travaux Publics, Sir Robert McAlpine and VolkerFitzpatrick) is leading the viaduct project.

HS2 senior project manager Billy Ahluwalia said: “Our work to install the viaduct’s remaining deck segments continues at pace, followed by the installation of the deck edge parapets and noise barriers, before we hand over to Rail Systems for the next major phase of the build programme.”

A four-day closure over the Easter weekend allowed engineers to work on two piers which will carry Small Dean Viaduct over the London Marylebone-Aylesbury line south of Wendover in Buckinghamshire.

A bus link for rail passengers was provided between Aylesbury Vale Parkway and Beaconsfield stations during the work which included the construction of 49 metre-deep (160 feet) piled foundations for the pier east of the existing line, and lifting a 42 tonne ‘Y’shaped segment onto the pier to its west. A total of six piers will be required to support the 345 metre-long (377 yards) viaduct which will also cross the A413.

The 700-tonne launching girder, which moves concrete deck segments into place, is seen on the span of the Colne Valley Viaduct which crosses the Grand Union Canal. It will continue its journey northwards for just over half-a-mile to complete the remainder of the spans, piers for which are already in place. As can be seen in this image, the structure also crosses a series of lakes. Its 2.1 mile total length will also take it over the River Colne and local roads. HS2