>How did they build those deep tunnels before the invention of TBMs? Same approa...

		Havoc 9 months ago \| parent \| context \| favorite \| on: What if every city had a London Overground? >How did they build those deep tunnels before the invention of TBMs? Same approach as TBMs just manual AF. Dig a bit, put in supporting structure. Rinse and repeat. They've been at it since 1890 though so that helps