Amersham vent shaft
There will be four ventilation shafts and one intervention shaft in the tunnel across the Chilterns. These would also be used for emergency access during operation. All the ventilation shafts use the same diaphragm wall construction method. The third of these is in Whielden Lane, Amersham. A footpath and cycleway will be diverted for a year before being reinstated alongside Whielden Lane. There have been alterations to the junction of Whielden Lane and the A404 and temporary traffic lights installed to control the junction. There will also be slight alterations to the junctions of the A404 with the A413 and the A413 with the A355 Gore Hill. The vent shaft depth will be 40 metres. Tunnel boring machines are due to reach here in Sept. 2022. The vent shaft is due to be completed by April 2025. The approved access route is via the A404, A413, A355 to Beaconsfield then the A40 and the M40.