Roundabouts are a commonly adopted intersection treatment in Western Australia due to their road safety benefits (i.e. low speeds and improved impact angles).  To achieve the desired safety improvements offered by a roundabout, speeds are controlled through geometry, but road designers also need to consider the stability of heavy vehicles, with high centres of gravity, while negotiating the roundabout.  This is particularly relevant where approach speeds are high or if the roundabout geometry is tightly constrained by location.

Heavy vehicle stability analyses are undertaken during the design of all roundabouts meeting certain approach speed and location criteria.  The assessment is based on estimating the Load Transfer Ratio (LTR) of a representative heavy vehicle as it travels through a roundabout.  Speed and travel path are often estimated according to roundabout geometry and representative heavy vehicle type.  This project aims to capture real-world speeds and travel paths of different heavy vehicles passing through different roundabouts in the greater Perth Metropolitan Area.  Collection of this data will help validate common assumptions in stability analysis and ensure heavy vehicles can safely negotiate these intersections without risk of roll-over.