Sixty years ago a civil engineer called John Bartlett of Mott, Hay & Anderson had a revolutionary idea. He noticed that bentonite clay could be used in a slurry to stabilise the face of tunnels during excavation. This could prevent non-cohesive, water bearing soils from collapsing inwards making excavation safer and cheaper.  

The first prototype of his bentonite tunnel boring machine was tested in 1971 at New Cross in East London and in this episode we explore the ways in which this success led to the development of pressurised face tunnel boring machines and opened new possibilities for underground connections all over the world. 

We also talk with John Bartlett’s son Mike to find out more about the man who revolutionised soft ground tunnelling, before looking to the future at  projects that continue to push the boundaries of underground design and construction in soft soils.

Guests

Mike Bartlett, son of bentonite shield inventor John Bartlett

Emily Farmer, tunnelling engineer, Mott MacDonald

Sam Lo Grasso, principal structural engineer tunnelling, Mott MacDonald

Mike Savill, global practice leader for tunnelling, Mott MacDonald

Andy Thompson, head of tunnel design, US East Coast, Mott MacDonald

Partner

Mott MacDonald is a global engineering, management and development consultancy focussed on improving society by considering social outcomes and relentlessly focussing on excellence and digital innovation.