Twin Tunnels, Idaho Springs, COLORADO


  • RTD Light Rail Over CMD Tracks, Steel Arch Bridge
  • RTD Light Rail Over CMD Tracks, Steel Arch Bridge
  • RTD Light Rail Over CMD Tracks, Steel Arch Bridge
  • RTD Light Rail Over CMD Tracks, Steel Arch Bridge
  • RTD Light Rail Over CMD Tracks, Steel Arch Bridge
  • RTD Light Rail Over CMD Tracks, Steel Arch Bridge
  • RTD Light Rail Over CMD Tracks, Steel Arch Bridge
  • RTD Light Rail Over CMD Tracks, Steel Arch Bridge
  • RTD Light Rail Over CMD Tracks, Steel Arch Bridge
  • RTD Light Rail Over CMD Tracks, Steel Arch Bridge
  • RTD Light Rail Over CMD Tracks, Steel Arch Bridge
  • RTD Light Rail Over CMD Tracks, Steel Arch Bridge
  • RTD Light Rail Over CMD Tracks, Steel Arch Bridge
  • RTD Light Rail Over CMD Tracks, Steel Arch Bridge
  • RTD Light Rail Over CMD Tracks, Steel Arch Bridge
  • RTD Light Rail Over CMD Tracks, Steel Arch Bridge

Video of Idaho Springs Tunnel Blast

Project Summary


Curved Steel Plate Girder Bridge

The Twin Tunnels CMGC project is a two phase widening of the East bound and West bound tunnels at Idaho Springs, Colorado. Each tunnel widening will almost double the width of each of the tunnels. The bridge designed on the project is a 3 span prestressed concrete bridge intended to replace half of the existing structure currently in service. The bridge is 302'-8" long with a maximum span length of 159'-2".

Project cost: $110 Million

Client: Edward Kraemer & Sons, Inc/Obayashi JV

Services Performed


  • Design of falsework and temporary structures for the Clear Creek Bridge.
  • Design of EB & WB Tunnel portal blast protection frame.
  • Retrofit of portal frame for Tunnel rebar hoisting.
  • Design of rock fall wall & fencing.
  • Design of access bridge.
  • Evaluation of heavy equipment and crane loads on existing bridge.
  • Development of erection manual.
  • Design of rigging and lifting equipment.
  • Demolition plan development.
  • Mass concrete plan development.
  • Integrated working drawings.

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