Abstract Manager

Undertaking the Highway 400 widening and Anne Street Bridge replacement project in Barrie, Ontario, within a confined urban setting posed various challenges. The original Highway 400 was constructed in the 1950s, with a two-span bridge over the highway at Anne Street. This project demanded innovative solutions to meet current transportation needs while considering future expansion plans.
Setting highway geometry required a thorough review of various permanent and temporary constraints, including limited right-of-way, existing utilities, high traffic volumes, and more. The following outlines a few of the key geometric design items that were dealt with during the detailed design.
On Highway 400, the decision to shift the alignment by 5 meters was primarily driven by property considerations. This strategic shift reduced property requirements and avoided the complexity of constructing new piers on top of the old pile foundation system.

The 1-meter grade lowering on Highway 400 was necessitated by the need for a substantially wider structure (almost double the existing width) to accommodate future municipal initiatives along Anne Street (cycling lanes). In addition to the highway lowering, Anne Street still required a grade raise to achieve the vertical clearance requirements. A 1.2m grade raise on Anne Street was needed. To ensure the adjacent Church, residential, and commercial properties impacts were limited, comfort criteria were applied with a minimum K value for a design speed of 60 km/h.
 

To complete the highway construction, four stages were required to ensure that three lanes of traffic were maintained in each direction. In addition, the existing highway was designed for a 110 km/h design speed, where we were attempting to utilize a 120km/h design speed for staging wherever possible. However, due to the site constraints, a regulatory speed reduction to 80km/h was required as a 100km/h design speed was the maximum that could be achieved for the horizontal alignment in select stages.

The successful completion of this project exemplifies the strategic integration of geometric design principles, site constraints, and constructability considerations in freeway widening within a confined urban setting. The project not only addressed immediate demands but also laid the groundwork for future expansion.