Herrenknecht to build world's largest TBMA 19.25 m-diameter Mixshield to be manufactured by Herrenknecht for Russian concessionaire NCC to build the Orlovski road tunnel in central St Petersburg will be the world's largest. The diameter is 3.7 m greater than the current record holder, a Herrenknecht 15.55 m-diameter machine working at Italy's Sparvo tunnel. Since 1995, Herrenknecht has upped the record eight times. Read the full press release, which lists those records, and visit www.herrenknecht.com. 33/11. Prime minister Vladimir Putin meets Dr-Ing E. h. Martin Herrenknecht