CityLink Tulla widening project

Client Name
CPB Contractors
Melbourne, Australia
  • Acoustics & vibration


The CityLink Tulla Widening (CTW) Project aims to increase capacity, reduce travel times and improve safety on CityLink and the Tullamarine and West Gate Freeways.

The scope of the project included an Automatic Incident Detection (AID) system to alert traffic controllers to incidents in real time. Installed as a gantry-mounted camera, the video-based AID system is very sensitive to vibration.

High vibration risks damage to the cameras, prevents the AID system functioning properly, makes direct observations of the camera feed difficult and can even induce motion-sickness in traffic controllers.


Initial trials of the gantry-mounted cameras indicated that vibration limits were regularly being exceeded. SLR demonstrated that the root cause was predominantly large trucks travelling at speed over elevated road deck spans.


To mitigate these issues, SLR developed an innovative, modular, rapid-development tune mass damper system to reduce camera vibration. The developed tuned mass damper system successfully reduced vibration to acceptable levels. This meant that the existing gantries could be retained, eliminating the need to modify or replace the newly installed gantries. The developed tuned mass dampers also had a very small form-factor and did not significantly alter the gantries’ appearance.