State and county delivered bridge replacement project analysis : phase I and phase II.

PDFTech ReportOR-RD-10-13Bridge constructionProject deliveryConstruction projectsRoad constructionOregonOregon. Dept. of TransportationDoolen, Toni L.Behmardi, BehrouzOregon. Dept. of TransportationUS Transportation CollectionThe purpose of the study was to compare the cost of state delivered bridge projects and county delivered bridge projects. A total of 190 different bridge replacement projects were analyzed. The first phase of the project focused on whether or not the project delivery type (state or county) was a significant predictor of project cost or project duration. The greatest variability in the cost of bridge replacement projects (79%), was found to be explained by project duration and bridge length, with length being the most influential. Overall, it was found that the duration of state\ue2\u20ac?delivered projects was longer than the duration of county\ue2\u20ac?delivered projects.In the second phase, analysis was completed to determine if a predictive model could be developed for project costs and project duration. Variables included bridge closure type (on\ue2\u20ac?site detour, off\ue2\u20ac?site detour, and staged build), clearance type (over water, over railroad, over canal/irrigation), number of bids received, and project location. Clearance type was found to impact construction costs, but not be a significant predictor. It was also found that projects built in stages had higher construction costs than projects using onsite or offsite detours. Using the results from Phase I and analysis from Phase II, a model was developed. The model was found to account for 86% of variation in project costs