M3 at M City Prepares for Tuned Mass Damper Installation

DEVELOPMENT CONSTRUCTION
October 30, 2025 by Anthony Teles 138

M3 is preparing to install the Tuned Mass damper at M City

Earlier this month, M3 in M ​​City celebrated a major milestone with a topping out ceremony, marking the completion of concrete formwork at the top of the building. The 77-story tower, part of the multi-phase M City project in downtown Mississauga and designed by Arcadis for Rogers Real Estate Development and Urban Capital Property Group, is now the tallest building west of Toronto in Canada.

Attendees gather on the 77th floor for the M3 topping out ceremony, image by UrbanToronto Forum contributor Steveve

As construction progresses to erecting the summit's steel beam, crews are also assembling the building's massive Tuned Mass Damper (TMD); This pendulum system stabilizes the slim structure by oscillating against the movement of the tower, ensuring occupant comfort. Adam Segal, construction manager at Urban Capital, provided UrbanToronto with more details about the TMD system and its installation in a three-story concrete void and is now awaiting the frame that will hold the TMD before the TMD and surrounding cladding are installed.

Looking northeast at the three-story concrete shell above that frames the space with tuned mass dampers, image by UrbanToronto Forum contributor drum118

A bird's-eye view into the crown shows the three-story concrete chamber where assembly of the 705-ton steel weight (705,000 kg or 1,554,258.95 pounds) is underway. In the middle of the chamber, prefabricated steel elements form the core frame of the damper, while thick counterweight plates are arranged for assembly. These panels were delivered in 65 truckloads, with the system taking approximately two months to assemble.

Top view of the steel components of the M3's 705-ton tuned mass damper, image by UrbanToronto Forum contributor Tim MacDonald

Viewed from the front, this image provides a clear view of the giant steel object that forms the core of M3's TMD, where the labeled steel plates (each etched for identification and alignment) are positioned within the three-story concrete enclosure. Next steps include installing long-span supports that will suspend the damper from the crown structure above. Yellow ladders and a blue elevator remain on site as crews complete assembly ahead of the system's tuning phase scheduled for January 2026.

Frontal view of the thick, lettered steel plates that form the core of the M3's tuned mass damper, image by UrbanToronto Forum contributor Tim MacDonald

Looking north towards the M3 from Webb Drive, this image captures the current extent of M City, with the M3 dominating the centre. The tower's open cavity at the crown is visible from the slope. Meanwhile, M1 and M2 (rotated 90° to each other and identified by their accordion-like silhouettes) stand on the right and the cranes for M4 and M5 protrude into the foreground on the left and right, respectively.

Looking north from Webb Drive towards M City, with M3 in the middle and visible cranes for M4 and M5 in the foreground, image by ImmenselyMental, UrbanToronto Forum contributor

Work on enclosing the TMD chamber will begin soon. The west façade will soon be completed with a steel frame before the crown steel is erected. Once this uppermost structure is clad in glazing and perimeter railings, teams will install M3's BMU (Building Maintenance Unit), then dismantle the external hoists and finally dismantle the crane, signaling the end of heavy construction work as the tower is completed in summer 2026. At 260.29 m and 879 units, M3 is both Mississauga's tallest building and the tallest in Canada outside of Toronto.

Looking northwest on M3 at M City, M City, designed by Arcadis for Rogers Real Estate Development Ltd and Urban Capital Property Group

UrbanToronto will continue to monitor the progress of these developments, but in the meantime you can learn more in our database files linked below. If you'd like, you can join the discussions in the associated Project Forum threads or leave a comment in the designated area on this page.

* * *

UrbanToronto's research and data service, UTPro, provides comprehensive data on construction projects in the Greater Golden Horseshoe – from proposal to completion. Other services include instant reports, downloadable snapshots based on location, and a daily subscription newsletter, New Development Insider, that tracks projects from the first application.​