AWARD OF EXCELLENCE – TRANSPORATION Dufferin Street Underpass

For more than 100 years the southbound journey on Dufferin Street in Toronto was stopped short by a major, multi-track rail corridor. Cars, buses and emergency vehicles alike were forced to turn left, entering the infamous “Dufferin Jog.” This three block circuitous route through a residential neighbourhood added only time and confusion to those travelling south.

Delcan was contracted to remedy this by designing and engineering a solution to seamlessly link the two parts of Dufferin Street. The city of Toronto billed the project as an exercise in “urban place-making,” wanting both to improve access and revitalize the community at the same time.

Delcan’s crisp urban design met the requirements by drawing on community input and imagining a bright, open corridor, with a stone parkette, a grassy knoll and well-lit walls for the installation of art.

At the same time, they designed a straight-through alignment for the underpass, which minimized the taking of property and provided the smallest footprint.

The technical challenge was that the underpass needed to be constructed under a busy multi-rail corridor.

To achieve this, the designers elected to raise two rail tracks marginally rather than lower the roadway. This allowed the existing traffic to continue undisrupted, while limiting major works on the railway corridor itself.

The engineering design evolved to a scheme to “sneak” in a rigid frame structure beneath the railway tracks, creating a “bridge on a bridge.” Observing minimal clearances, tight confines and very large loads, the new underpass was built to have the existing railway bridge actually supported on the underpass’ roof.

The scheme involved no changes to the grades of Queen Street and Dufferin Street, but instead involved raising two of the railway tracks by about 1 metre, a process that was much easier to accomplish than the lowering of Queen Street and Dufferin Street.

A compact reinforced concrete twin-cell rigid frame structure was built in a sequential manner to accommodate train traffic throughout construction, and with the goal of having virtually no effect on vehicular traffic on Queen Street, Dufferin Street or adjacent streets. None of these streets was ever closed during construction.

The scope of Delcan’s design and engineering included everything from concept design to environmental assessment, structural engineering, electrical engineering, utilities relocation, stormwater management, landscaping and public consultations.

In November 2010, the new Dufferin Underpass opened to ringing endorsements. Travel times through the area were reduced and the Toronto Transit Commission announced expected savings of close to $450,000 per year by making Dufferin bus trips more efficient.

Plans are under way to improve the formerly “trapped” neighbourhood north of Queen Street West with pedestrian walkways and bike-friendly features that will help to promote the area’s vitality and growth.

The project’s creative engineering solution has solved a century old problem while reinvigorating a downtown community. cce

Project name:

Dufferin Street Underpass, Toronto

Award-winning firm (prime consultant):

Delcan, Markham, Ont. (Joanne McCall, P.Eng., Brent Archibald, P.Eng., Bill Moore, P.Eng., Jonathan Werner, P.Eng., Vic Anderson, P.Eng., Thomas Woods, P.Eng., Sami Ibrahim, P.Eng., David Yaeger, P.Eng.)

Owner:

City of Toronto

Other key players:

Golder Associates (geotechnical); McCormick Rankin Corporation (contract administration, resident services); Dufferin Construction (general contractor).