Empirical investigation of life cycle cost of road studs on national roads
Thesis (MBA)--Stellenbosch University, 2013.
ENGLISH ABSTRACT: The study involved a detail empirical investigation into the different road studs in use on South Africa’s national road network and how they performed on the network under different road conditions in order to establish which road stud, under what conditions, offers best value for money in terms of life-cycle cost for the South African National Roads Agency Limited. These main questions were asked: What is the most cost-effective/value-for-money stud option for SANRAL to choose for each of the specified road categories? Under which conditions do the studs perform differently and what is the most likely mode of failure of specific studs linked to a specific road condition and road category? The South African and Australian road stud standards were reviewed to gain understanding of which criteria one has to consider when evaluating road studs and what information would be needed for the research. Similar studies on road studs were reviewed to compare the criteria that were looked at, namely Guidelines for the use of Raised Pavement Markers, developed by the Department of Transport in the United States, and Feasibility of using accelerated pavement testing to evaluate the long term performance of raised pavement markers, a research paper by the Florida Department of Transport. This research made use of a standardised questionnaire containing questions on various elements found to be key to the road stud performance. The study was done on approximately 4 659 km of roads in SANRAL’s Western region, consisting of the Western Cape and Northern Cape. From the literature review, it was identified that there is a need for the SABS standards to be updated to include the testing of structural properties of studs. SANRAL should look at the lack in specification requirements when asking for the installation of road studs. From the data available it was observed that the preferred studs were the Ferro Lynx followed by the STA+52 stud. They are predominantly used on the roads that were included in the survey. They perform well on the national roads. The data suggests that these two studs and the Rhino stud are the best-performing studs with the least dislodgement and loss in reflectivity. The STA+52 and Rhino stud, however, are fairly new on the market and more data for theirs full life cycle should be obtained for further monitoring The regression analysis indicated that 36 per cent of the variation in the reflectivity of the Ferro Lynx stud can be explained by the surface width of the road, the traffic volume measured as ELVS and the period installed. All the coefficients were significant with a 5 per cent significance. The prediction tables on the weighted data set, indicated that one should always consider width of road when choosing a road stud and that the reflectivity of studs deteriorates most on the narrower roads.