All roundabouts have a series of curves that limit vehicle speeds; however,  heavy vehicles using high-speed roundabouts tend to roll over. This study investigates the geometric design of high-speed roundabouts in relation to their use by heavy vehicles; towards the development of a revised design guideline. Two roundabouts in northern Queensland which had similar problems were selected for investigation. Video cameras and pneumatic tubes were used to determine semi-trailers’ travel path and their corresponding speed changes while navigating the roundabouts. In addition, as-constructed 3D models of the roundabouts were also obtained. Autoturn software was used to simulate the travel path, and 12D road design software was used to model and determine the actual radii and crossfall that an individual vehicle encountered.  By combining the above with speed data, the side friction generated by the vehicles and the rate of rotation of crossfalls encountered were determined and compared to relevant design standards. Results revealed that the rotation rate was more than allowable for trucks at high speed, leading to proposed modifications to geometric considerations. A supplementary set of standards was developed, which recommend combinations of geometry alterations, signage, and line-marking to more safely cater to heavy vehicles at high-speed roundabouts.