This report concerns a research track experiment to test and compare four alternative priority markings for simple t-junctions, two of which were unconventional designs which it is considered could improve safety. No measurement of 'safety' could be made in the experiment: in this respect the objective was to test operating feasibility as an essential preliminary to any safety trial on public roads. The objective of the work is to devise generally-applicable, low cost modifications to existing conventional major/minor t-junctions, which would reduce accidents on urban local distributor roads. Design considerations suggest that safety might be improved by reallocating priority in the junction, and reducing the speed at which it is possible to pass through the junction. Attention was concentrated on designs in which the 'major' road was defined to turn on either the left shoulder or the right shoulder of the t. Both designs were shown to operate satisfactorily, and it is concluded that trials could be held at junctions on public roads, which would not have traffic engineering disbenefits, and would be acceptable to drivers. The track experiment gave an indication that the left shoulder design might be preferred by drivers, and might also be marginally easier to use than a mini-roundabout junction. Accordingly, the report recommends several pilot installations of the left shoulder design in preparation for a multi-site trial on a scale sufficient to measure any change in accident rate produced by the modification to the conventional major/minor priority markings. It is envisaged that if the turning-priority designs are successful, they could have wide applicability, and could also be a major component of traffic management technique for residential suburbs. (Author/publisher)
Abstract