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Capitol Hill Station, United States of America

Project data

Location: Seattle, United States

  • Expansion of the metropolitan railway system (Light Rail) of Seattle by 5 km and 2 new stations
  • 100 m long Capitol Hill subway station at a depth of 18 m
  • Lateral bracing of the underground structure by means of steel composite tubes on two levels


  • Single-sided construction of the tunnel walls
  • Realization of the massive, up to 1.70 m thick edge beams and 1.20 m thick tunnel slab
  • Completion on schedule and within budget
  • Installation and concreting of the constructively stiffening steel composite tubes with 1.00 m and 1.50 m diameters


Turner Construction, Seattle, USA

Customer's benefit

  • Less construction joints along with minimum assembly time and expense due to monolithic construction of the walls and reinforced concrete beams
  • Considerable time and cost benefits through the optimized construction method as well as the use of rentable system components which were available at very short notice
Statement, Kevin Whalen, Superintendent: Capitol Hill Station, Seattle, USA
Kevin Whalen

Working in collaboration, PERI and Turner Construction designed the Traveling Mono System which has met scheduling and budgetary constraints. We've increased the level of safety for our workers as well as reduced the number of man hours required to set up traditional formwork systems. This system was specifically designed to pour concrete from the ground to the roof giving us ability to maximize our labor force and allow subcontractors to work beneath the system, all while improving on the quality of the finished product.

PERI solution

  • Customized formwork carriage solution on the basis of the VARIOKIT engineering construction kit for lateral bracing of the walls realized through single-sided forming operations as well as load-bearing system for the edge beams
  • Two-part construction for three different formwork heights
  • Hydraulically operated formwork carriage, movable along the edge beams
  • Temporary support of the edge beams with HD 200 heavy-duty props
  • Comprehensive project solution using formwork and scaffolding from the extensive PERI product portfolio