75% of the tunnels dug
At the beginning of August, Align’s tunnel boring machines Florence and Cecilia reached a major milestone on their journey: the Little Missenden shaft, the fourth of the five ventilation shafts on their route. This means that over 75% of the Chiltern tunnels have now been excavated - a great achievement for all the teams involved!
For over two years, these two gigantic underground machines, each weighing 2,000 tonnes, have been digging the tunnels, and they are now approximately 12km into their journey, having excavated over 2 million m3 of chalk and flint.
Little Missenden Shaft
The deck of the Colne Valley Viaduct continues to take shape
In order to minimise disruption relating to the construction of the Colne Valley Viaduct on the local community, Align completed the erection of a 40m span of the viaduct over a local road using at 650 tonne crane, during the summer holiday period.
The viaduct deck segments are normally put in place by the launching girder Dominique, however as the girder was not scheduled to reach the road until later in the year, a crane was used to complete the span, to coincide with the summer holidays, when traffic is lighter.
Align’s Surface Operations Director, Derek Van Rensburg commented:
“Having the flexibility to introduce a crane to complete the span across the local road during the summer holidays rather than using the launching girder, thereby minimising the impact on the local community, is all credit to the Align team involved.”
Once complete, the viaduct will be the longest railway bridge in the UK, stretching for 3.4km across the Colne Valley to the west of London.
Important milestones delivered for 2023
In August, the teams also reached the last two of their “Key Dates” for 2023, corresponding to major milestones set for the year. This achievement means that Align has repeated its success from the past two years and delivered all four key dates for the year
Named "KD23" and "KD24", they mark the completion of the viaduct deck erection up to pier 34 and the completion of the concrete base slab for the shallow basement at the Amersham vent shaft on the Chiltern tunnels.
Congratulations to everyone on all this progress.