Development of Objective Payment Adjustment Criteria for Nova Scotia

Most highway agencies in North America adopt specifications to control the level of initial roughness of new or rehabilitated pavements. Previous studies have indicated that high initial roughness results in higher Life Cycle Costs (LCCs). Therefore, controlling initial roughness leads to longer pavement service life, lower maintenance and rehabilitation costs, and consequently to more cost-effective pavements. Smoothness acceptance specifications typically include a value for acceptable initial roughness (in terms of a roughness index), together with payment adjustment factors that result in full payment, a bonus, or a penalty to the contractor. This paper summarizes an initiative to review the current smoothness acceptance specification of the Nova Scotia Department of Transportation and Public Works (TPW), which had been in place for about 15 years, and to evaluate the benefits of other equipment, roughness indices and payment adjustment factors. This initiative was geared towards developing and proposing an alternative smoothness acceptance specification that the province could choose to implement. Within this paper, a particular emphasis is placed on the effort made to objectively identify the impact of initial roughness on expected pavement service life, and hence objectively determine the levels of bonus and penalty that should be awarded to contractors. Two alternative approaches were considered to objectively quantify the impact of initial roughness on the pavement economics. Comparisons between TPW’s current specification, the specifications of three other Departments of Transportation (DOTs) in US and Canada, and the two alternative approaches developed, are presented in this paper.