State and County Delivered Bridge Replacement Project Analysis: Phase I and Phase II

摘要

The 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-delivered projects was longer than the duration of county-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-site detour, off-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.