Canadian Consulting Engineer
TORONTO WATERFRONT: The End of An Era – Dismantling the East GardinerEngineering
Two years ago Toronto city council decided to dismantle the easternmost portion of the Gardiner Expressway, the elevated road that runs east to west downtown. Though opponents were afraid removing the...
Two years ago Toronto city council decided to dismantle the easternmost portion of the Gardiner Expressway, the elevated road that runs east to west downtown. Though opponents were afraid removing the artery would add to the city’s traffic congestion, urban designers and people in the nearby Riverdale community saw the roadway as a barrier between the city and Lake Ontario, and they campaigned to have the roadway taken down. In the end, economics largely drove the decision; dismantling rather than maintaining the road should save $14 million over 50 years.
Toronto consulting engineers Cole, Sherman & Associates had done the original environmental assessment study and in 1998 took on the role of prime engineering consultant for the demolition and new construction.
Approximately 1.3 kilometres of the structure have been removed, from east of the Don Valley Parkway to Leslie Street. Built around 1964, this stretch of the Gardiner was planned as an expressway to Scarborough but the route out to the suburbs was never realized. Planners at the time envisioned a network of highways crisscrossing the city, but they found their dreams soon thwarted by citizen groups who felt such throughways destroyed historical neighbourhoods and divided the urban fabric.
The demolished Gardiner section consisted of a 235-mm thick concrete deck resting on 20-metre long steel girders supported on concrete bents. Over the years water leaking through its expansion joints had deteriorated the structure. It rode over the top of Lakeshore Boulevard, a wide surface artery that will now accommodate the rerouted traffic.
The demolition of the structure was the longest of its kind undertaken by the city. Because of the risk of damaging underground utilities and adjacent buildings, it was dismantled conventionally. The concrete was taken for recycling as a base for the new roadway.
Cole Sherman was responsible for the design of the new Lakeshore roadway as well as detour routes to keep traffic flowing during construction. Public consultations were critical, and the plans were complicated by the presence of a nearby rail spur.
The reconfigured Lakeshore Boulevard from Leslie Street has four lanes in each direction, leading to two new on/off ramps designed by Morrison Hershfield that connect to the remaining elevated Gardiner. Studies show that vehicles will take only one minute longer to travel the distance along the new Lakeshore than they did using the elevated expressway.
The new section of Lakeshore Boulevard has bicycle and pedestrian paths, new pedestrian bridges, public art work (portions of the old expressway illuminated) and extensive landscaping planned for 2002. According to On the Level, a city newsletter, the artery will be transformed into an idyllic place: “Imagine new cycling and walking trails where shadows from an overhanging expressway once dominated. Picture new groves of trees and pleasing landscaping in place of deteriorating concrete, weeds and wasted open space.”
Client: City of Toronto (David Crichton)
Prime consultant: Cole, Sherman & Associates, Toronto (Murray D. Thompson, P.Eng.)
Other key players: Morrison Hershfield (structural), DuToit Allsopp Hillier (urban design), LURA (public consultation), GeoCanada (geotechnical), S.S. Wilson Assoc. (noise and vibrations); Grascan Construction and Torbridge Construction (contractors)
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