Winner, (Transit NZ / Works Infrastructure) NZ Road Innovation Award 2003; Highly Commended, NZAA Prize for Best Paper. Recent research investigated ways of analysing and providing for improved passing opportunities on rural highways in New Zealand. This paper focuses on the studies of the performance of slow vehicle bays. Field surveys at eight sites identified the effect of different features on usage and bunching reduction. The surveys observed higher levels of use than found overseas, however the effect on vehicle bunching was generally not significant. Minimum desirable lengths for slow vehicle bays were also reviewed and safety effects considered. From this, project evaluation methods using either simplified procedures or TRARR simulation modelling were developed.