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LONG DISTANCE CURVED MICROTUNNELLING RAISES THE BAR IN ONTARIO (2014)
Prior to 2012, the integration of designed vertical or horizontal curves into microtunnel alignments was unheard of in Ontario. Straight and relatively short microtunnels, less than 200m long, were the local accepted industry standard. Following the release of a large number of infrastructure projects in the suburban Greater Toronto Area (GTA), clients and design consultants encouraged contractors to present value engineered alternatives to proposed project alignments and construction methods. Such an initiative has allowed contractors to develop cost effective solutions, which harnessed the application of state of the art microtunnelling methods and equipment. As a result, several recent projects now feature pre-designed curved microtunnels as part of the tender documents. This paper discusses, in technical detail, three recent projects, whereby, long distance curved microtunnels were successfully constructed. Each of the projects had tunnel drives exceeding 300m in length, ranging in diameter from 1200mm ID to 1500mm ID, incorporating the use of Vertical, Horizontal, and Spatial Curves. Critical parameters such as pre-project planning and engineering are highlighted, while the importance of post-tunnelling assessments is also discussed.
Tunnelling in a Resource Driven World, Vancouver TAC 2014, 26-28 Oktober 2014
Ward and Burke Microtunnelling Ltd., Mississauga, Ontario, Canada