The Thames Tideway Tunnel is a 25 km long stormwater storage tunnel, up to 65m deep beneath central London and incorporating twenty shafts and ten smaller diameter connection tunnels. It has been constructed through the entire London Basin geological sequence which has had a significant influence on its design.

The large-scale underground structures excavated during construction have facilitated observations of the in-situ geology and revealed sedimentary characteristics that could not be fully evident in disturbed samples from ground investigation boreholes and laboratory tests. These have led to significant improvements in understanding the in-situ groundmass behaviour of several strata within the sequence and their impact on the performance of different construction techniques.

Dr Tim Newman is a chartered geologist and engineer with over 30 years’ experience in geology and geotechnics and a PhD in the causes of confined space hypoxia during underground construction in the Lambeth Group. He started his career as a mining geologist in Australia and then Botswana, followed by several years with Taylor Woodrow on a number of chalk tunnels and the Jubilee Line Extension. Later, Tim worked for Thames Water on their Ring Main extensions and Lee Tunnel, plus the initial ground investigations for the Thames Tideway Tunnel. He joined Jacobs to continue geological supervision of this during construction, logging most of the 20 shafts, small connection tunnels and the main tunnel when the opportunity arose to enter the TBM. More recently, Tim has been involved in the production of geotechnical baseline reports (GBRs) for the Haweswater Aqueduct Resilience Programme tunnels in the north of England.