World's largest TBM completes first drive21 August 2012
The TBM being used to build a twin-tube Sparvo road tunnel located between Bologna and Florence, broke through the northbound tunnel of on 25 July.
The colossal 15.615m machine was manufactured by Herrenknecht in an EPBM setup. It was equipped with 76 disc cutters, 216 cutting knives, 24 buckets and one centre cutter.
The tunnel is 2,431m long with a 13.6m inside diameter. It will accommodate a triple-lane carriageway, including an emergency lane, 3.75m wide each.
The tunnel will be equipped with 10 bypass - two of them for vehicles - and 17 SOS posts for emergency calls.
Shortly after mid-August this year, the shield will be rotated 180 degrees, and it will take three months to assemble the TBM again in the new cradle, ready to bore the southbound tunnel.