If you live or work near the future route of the Yonge North Subway Extension, you may start noticing something new appearing around your community. 

Some of these additions might be easy to miss, like reflective targets attached to buildings or walls. In other areas, you may notice equipment mounted on poles or other structures near roads and sidewalks. 

These are monitoring devices, and they are being set up ahead of future tunnelling and construction. This equipment is commonly used on large transit projects around the world, helping teams safely plan and build things like subway tunnels and stations.  

Before construction begins, the monitors help establish a baseline picture of existing conditions in the area, including ground conditions, air quality, noise and vibration, and the location of nearby buildings and structures. Once work begins, the monitors can detect even very small changes over time, helping construction teams track conditions and make sure work is moving forward according to plans. 

Depending on the location and type of work planned nearby, some monitoring equipment may remain in place for an extended period of time. 

As work continues, Metrolinx will continue to reach out to communities with updates about upcoming construction activities and what to expect in your area. 

Want to learn more? Dig deep into how tunnelling works and learn about how noise and vibration are monitored and managed during construction.