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. The second of these will be in Bottom House Farm Lane, Chalfont St Giles which will be closed to through traffic for approximately two years. The shaft depth here is 32 metres. The tunnel boring machines will reach here in August 2022. The vent shaft is due to be completed by January 2025. Access to the compound will be via a temporary haul road from a new junction with the A413. This will be removed once construction is complete and Bottom House Farm Lane will be widened but remain single track. Approximately one km. of the hedgerow has been be lost. Chalfont Valley Equestrian has closed to allow for the construction of the haul road. There will be no Public Right of Way (PRoW) closures or diversions. To protect water supplies a pipeline has been built between the Affinity Water pumping stations at Chalfont St Giles and Amersham. The approved access route is via the A413 to the A40 and then the M40. All HGVs will turn right when leaving the haul road. The junction will be controlled by temporary traffic lights.