Little Missenden 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 fourth of these will be alongside the A413 in Little Missenden. PRoW LMI 40/2 will be temporarily re-routed around the construction compound. The vent shaft depth will be 31 metres and the tunnel boring machines will reach here in August 2023. The vent shaft is due to be completed by April 2025. The site will also house an auto-transformer station. The approved access route is via the A413, A355 to Beaconsfield then the A40 and the M40. Traffic arriving at the site will do so via a traffic light controlled right hand turn across the dual carriageway.