A study of constructability related costs on selected Arizona department of transportation projects
Aman Mathur, Spring 2004
Brief:
Selected multi-million dollar highway projects administered by the Arizona Department of Transportation (ADOT) were studied as a part of this research in order to determine if the cost of constructability could be measured. Previous researchers have identified constructability costs for industrial and highway projects using only design alternatives to derive cost. This study proposes to capture constructability cost subsequent to construction using requests for information (RFI), change orders, other construction documents, and interview data. In the past, construction documents on transportation projects have not been evaluated to measure the cost of constructability A list of 866 projects awarded by ADOT between 1997 and 2002 was provided to the researcher and reduced to 95 projects by using certain criteria to obtain a consistent mix of project types. For a detailed study of constructability related costs, ten projects, distributed throughout the state of Arizona, were randomly selected from among the remaining 95. Two techniques were adopted to collect data from each of the ten selected projects. A standard questionnaire was developed to ensure that the subsequent interviews, of the project managers, resident engineers, and lead inspectors for each project, were consistent. Project records and documents were also reviewed. The collected data revealed that 16% of the expenditures on change orders for all of the ten projects combined were non-value-adding. Approximately 50% of the requests for information for all projects clearly indicated some lack of constructability considerations. Despite the contention of a previous National Cooperative Highway Research Program (NCHRP) study that the cost of design hours was 200 dollars, no cost could be effectively assigned to the RFIs based on project records and data. However, the direct cost of constructability-related change orders was easily determined. Because of the limited number of projects that could be effectively investigated through the interview and document evaluation process, the results of this study have no statistical significance. The primary value of this work has been to identify improved record keeping methods and project investigation timing that can provide more complete and accurate data for future ADOT constructability studies.