Publication Abstract

Proceedings of the 42nd Annual Conference on Deep Foundations, 2017, New Orleans, LA, USA, (DFI)

Prescriptive Specification Design: The Impact on Cost and Constructability - Case History
Shawna Munn, P.Eng, Allison Bennett, E.I.T. and Nadir Ansari, P.Eng, D.GE, M.ASCE

This paper outlines how specification driven design has made Toronto Area transit infrastructure projects more expensive than similar private projects, and provides a case study of the results of an excavation at Launch Shaft 1 (LS1) for the Eglinton Crosstown Light Rail Transit project in Toronto, Ontario. The paper will describe the impact specification driven design parameters can have on design economy, constructability, and schedule and will suggest an alternative approach utilizing the Observational Method. As a result of the initial specification based design, Isherwood was retained by both the General Contractor and the Specialty Excavation Shoring Contractor to provide value engineering leveraging the Observational Method to improve constructability and construction schedule. By using well known, accepted design methods coupled with local experience in lieu of the specified design pressures and parameters, the redesigned bracing scheme reduced construction cost and schedule. This excavation case history can be a lesson learned for future transit projects.

 article #2767; publication #1037 (AM-2017)