Surveying Requirements for Developments Near or Above TTC Tunnels

This guide outlines the specialized surveying procedures involved in developments located adjacent to or directly above TTC subway tunnels. It covers TTC records research, access requirements, field crew certification, tunnel entry approvals, three-dimensional field verification, geodetic control and the preparation of stratified reference plans where required. The document also explains how project requirements differ depending on whether tunnels cross the development site or are located nearby. Examples from Bloor & Yonge, Finch & Yonge, Bloor & University, and Sheppard & Yonge illustrate how tunnel proximity can affect survey methodology, legal plans, field access and project complexity.