Highway 401 Crossing - Construction Phase Services

Metrolinx and Infrastructure Ontario
Toronto Tunnel Partners - EllisDon & Strabag Joint Venture
$117 million CAD
February 2019 — August 2021
Services performed
Dr. G. Sauer & Partners provided design representation on site during the SEM construction phase to TTP in form of an SEM Geotechnical Engineer as well as PoR engineering support services to ensure design compliance.
TTP delivered a new two-track rail tunnel of approximately 188m length crossing the Highway 401. The purpose of the tracks is to increase capacity along the Kitchener GO commuter rail corridor as well as to accommodate the new Union-Pearson (UP) Express service. The new rail tunnels are mined under the 401/409 Highway using the Sequential Excavation Method (SEM). Our role during the construction phase was to provide Design Representation on Site through an SEM Engineer and Geotechnical Engineer as part of the daily review and decision-making process and signatures on the RES-sheet. We provided ongoing design support to accommodate TTP's schedule by designing and implementing a fast-ring closure sequence. The tunnel advance switched between the East Portal and West Portal (for tunnel 2) several times with updated design sequences. As PoR, we ensured compliance of design.
Granular and cohesive embankment fill underlain by glacial till underlain by glacial till. Subsurface obstructions such as piles and boulders.
Toronto, Canada


  • Participation in daily RES meeting with joint release of daily RES sheet
  • Small and large design changes to accommodate TTP's schedule needs
  • Quality control for waterproofing and final lining as PoR to ensure compliance with design

Final lining invert concrete pours and ongoing SEM construction.

Final lining concrete works at portal wall and sheet membrane waterproofing.