MRC Yonge Street Slip Tunnel Design

Colin Ahola and Mashrur Chowdhury
Case revision date: 
13 pages (Case Study)

McCormick Rankin Corporation (MRC) is an engineering consulting firm providing services in the fields of transportation, construction and environment. MRC was consulted by the Toronto Transit Commission (TTC) regarding the construction of a new streetcar tunnel under Queen’s Quay West. Upon investigation it was revealed that there is a timber crib structure under the Yonge Street slip along Queen’s Quay. The TTC was not aware of the crib structure’s existence and consequently their initial design work comprised of a straight tunnel passing along Queen’s Quay. As an alternative to rerouting the TTC would like to explore solutions such that a tunnel can pass straight through under Queen’s Quay as per their initial design.Existing TTC Harbourfrount Route

Colin Ahola, a civil engineering co-op student from the University of Waterloo, was asked to analyse three potential solutions that would enable the proposed tunnel to pass through the crib without having to change its horizontal alignment and recommend a solution. The three options were (1) jet grouting, (2) new bulkhead construction, and (3) permeation grouting.

Learning objectives: 

This case study seeks to demonstrate how socioeconomic and environmental factors pertain to civil engineering decisions. The case will also help illustrate the preliminary phases of the engineering design process. After completing the case study, students will be able to apply the principles governing grouting methods and bulkhead constructions, generate preliminary design solutions based on given constraints, generate a decision matrix to conduct an environmental analysis, and conduct a preliminary costing analysis and finally establish a final design solution. 

Key words: 
soil stabilization, grouting, bulkhead construction, tunnel construction
CEAB attributes: 
Problem Analysis; Design; Use of engineering tools; Impact of engineering on society and the environment
Module 01 – Case Study
Module 02 – Preliminary Design Alternatives
Module 03 – Environmental Analysis
Module 04 – Preliminary Costing Analysis
Module 05 – Recommended Solution
Module TN – Teaching Note

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