two others for smaller connection tunnels. It also required two types of construction sites: main tunnel sites, where the TBM was either launched or received, and CSO sites, where interception tunnels and a connection culvert were built to connect the existing sewer to the new tunnel. Construction of the shafts at the CSO sites, to transfer flows from the existing sewer to the tunnel, would vary depending on the depth, the amount of flow they need to carry and the geology. The shaft would be a concrete cylinder with an internal diameter of and deep. Ventilation structures at CSO sites to allow air in and out of the shaft were also required. Construction at these sites was expected to take between 2½ and 3½ years and once complete each site would be landscaped. At the main drive sites, four main activities took place: shaft construction (where a concrete cylinder in diameter and about deep was constructed), tunnelling preparations (preparing the site for arrival of the TBM), TBM assembly and lowering into the shaft, and then driving the TBM to excavate the main tunnel. As the TBM moved forward, precast concrete segments were brought in and fixed together to create the tunnel wall. Excavated material would be transported out the tunnel via a conveyor belt and processed before being taken off-site. In order to minimise disruption, Thames Water committed to use the river as much as possible to transport materials both in and out of the construction sites. At the main tunnelling sites, work was expected to occur 24 hours a day. In 2017, the public voted on a short-list of 17 to name the six TBMs. They were named after female pioneers of their fields linked to where each began to dig. One began tunnelling from Fulham in 2018, the Rachel Parsons, after the engineer and advocate for women's employment rights, who set up the first women-only engineering company in Fulham. The others were cryobiologist Audrey ‘Ursula’ Smith and suffragist Millicent Fawcett for the Central area and suffragist Charlotte Despard for the Frogmore Connection Tunnel from Wandsworth to Fulham. The TBM for the east section from Bermondsey was named after doctor Selina Fox who set up Bermondsey Medical Mission for Southwark's poor and disadvantaged residents. The machine for the Greenwich Connection Tunnel was named after Annie Scott Dill Russell, the first female scientist to work at the Greenwich Observatory. Planning