Dhakal, S; Mrawira, D and Rankin, J (2009) Effect of specifications type on the quality of paving contracts in New Brunswick. Journal of Construction Engineering and Management, 135(9), pp. 801-811. ISSN 0733-9364
Abstract
Construction specifications are used by transportation agencies to define the client's requirements of the final product. The primary motivation of adopting the newer end result specification (ERS) or performance related specification over method-based specification (MBS) is to reduce clients' costs, encourage contractors' innovation, and improve overall quality. However, some transportation agencies have been reluctant to fully implement ERS due to lack of demonstrated evidence on whether they achieve comparable level of quality or performance. This paper investigates if the specification type has any effect on quality. The case study presented is based on data from New Brunswick Department of Transportation (NBDOT) from years 2003-2007. NBDOT generally uses ERSs to call paving contracts equal to or larger than 8,000 t. MBSs are used for all other smaller paving contracts. The most prevalent indicator variables for accepting asphalt paving jobs in North America [that is, percent theoretical maximum relative density, asphalt binder content, air voids, voids in mineral aggregates, percent passing 4.75 mm (No. 4), and 75 μm (No. 200) sieves] were investigated. Statistical analysis was performed to compare the deviation of the quality indicator variables from their respective job mix formula values for paving projects that used MBS or ERS. ANOVA results revealed that there were no significant differences between the qualities achieved from the two specification types. Also, no significant differences were found from within-specification comparisons over the time frame examined. Given the possible cost advantages from agency's point of view, the flexibility of the contractors to innovate and the fact that this study demonstrates quality is not compromised, there is an opportunity for agencies to expand or fully adopt the use of ERS specifications.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | asphalt pavements; contracts; highway and road construction; quality control; specifications; variance analysis |
| Index terms: | asphalt pavement, statistical analysis, quality indicator, road construction, relative density, quality control, case study, deviation, paving, agency, aggregate, specification, variance analysis, transportation agency, evidence, motivation |
| Subjects: | data collection methods, contractual condition, sociology, data science, infrastructure and transport systems, psychology, materials science, material properties and characteristics, evaluation and assessment methods, financial and cost management, statistical analysis, project delivery, transportation engineering, civil engineering |
| Topics: | Engineering Principles, Research Practice, Contract Administration, Quality Management, Human Resources, Cost Management |
| Descriptive scope: | 5 PCTEA |
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