As part of a strategic project to collect, pump and treat wastewater from the southern part of the city of Doha, Bouygues Travaux Publics - working as part of a consortium with Bessac and local company UrbaCon Trading & Contracting - excavated 16.2 kilometres of tunnels for the new sewerage network. The tunnels were dug using two earth pressure tunnel boring machines at an average depth of 28 metres. For the first time at Bouygues Travaux Publics, part of the access shafts were dug using the Vertical Shaft Sinking Machine, a roadheader with a rotary cutter, enabling vertical excavation.