Mayerthorpe Rail Bridge Replacement

Canadian Consulting Engineering Award

Design and construction monitoring for replacement of vital rail link

On April 26, 2016, the wooden railway trestle bridge over the Little Paddle River, near the community of Mayerthorpe about 120 km northwest of Edmonton, Alberta, was vandalized and deliberately set on fire. The bridge was destroyed within a few hours, crippling the railway network owned by Canadian National Railway (CN). CN employed KCB to design the earthen approach embankments, provide input for the design of the bridge piles, and monitor the construction of the embankment approaches.

 

“We were very impressed with the team’s agility and ability to make design adjustments that adapted to very difficult ground conditions with limited time and data available.”

-CCE Jury

Challenges

  • The bridge needed to be re-built and service restored within three weeks
  • Suspected weak foundation soils under sections of proposed embankment
  • KCB’s drilling program for determining physical properties of approach embankment foundation revealed series of thick clay deposits

Solutions

  • Earth moving activities, pile and bridge pier installations, and bridge span construction activities occurred simultaneously on site
  • Embankment fills designed using observational approach which allowed adjustment of design to mitigate weak foundation conditions while construction proceeded
  • KCB’s designers added granular shear key to toe of eastern approach embankment and 5 m high berm to both embankments, to stabilize embankment

Successes

  • Bridge was back in service only 20 days after original bridge was destroyed by fire
  • Environmental impact of project reduced by reusing steel sections and using nearest available borrow material for approach fills
  • Experience based design which was confirmed through analysis allowed for fast tracked construction to proceed even before site investigation started