This thesis reports the use of Paramics microscopic simulation software to model the differences between the performance of ten Christchurch intersections under the existing New Zealand road rule which requires left turning vehicles to give way to vehicles turning right into the same road, and a changed rule that would see the right turning vehicle have priority. Previous research concerning this issue is reviewed and the history of the existing road rule and recent moves to change it are discussed. At each of the ten intersections a range of traffic volume combinations was assessed and the journey times and queue lengths were compared. The ten intersections represent a range of different layouts and forms of control including give way signs, stop signs and traffic signals. The impact of a rule change on the use of shared lanes at intersections using a Paramics model of the Christchurch Central Business District, as developed for the Christchurch City Council, is also reported. Conclusions are drawn about which types of intersections and traffic volume combinations are likely to be affected by a rule change. The features of intersections that contribute to this susceptibility are identified and conclusions drawn about whether positive or negative effects are likely. It is concluded that there is no compelling intersection performance reason why the rule could not be changed. The successful implication of such change would require a review of the road network to identify critical intersections. Some monitoring and mitigation measures may also be required.