A methodology for modeling the cost and duration of concrete highway bridges
Abstract
Accurately estimating the cost and duration of bridge projects is essential for optimally budgeting money and time for construction. An investigation of the current procedure used by the Transportation Department of the State of Indiana showed that it does not satisfy these important requirements. This research concentrated on analyzing an alternate methodology for optimizing cost estimating. In addition, the work offers a better strategy for estimating the duration of project construction. Three types of concrete highway bridge projects were analyzed. The projects were divided into five categories of work packages. These categories are Substructure, Superstructure, Road Approach, Traffic, and "Other." The cost of each category was modeled by applying multiple regression statistical techniques. The regression analysis considered two types of models: the geometric, which considers the physical aspects of the projects; and the material quantities, which consider the major material items that integrate the models. The material quantities model was more precise for the Substructure category, while the geometric model was more appropriate for the Superstructure and the category "Other." A combination of the geometric and the material quantities model was used to calculate the cost in the Approach category. The category Traffic was found to be dependent neither on the dimensions nor on the material quantities of the bridge projects. Duration models were analyzed with the same analytical approach. In this case, the geometric model was used for modeling the duration of the Superstructure and the Approach, while a combination of the geometric and the material quantities models was more representative for the Substructure duration. Although the duration of the projects cannot be obtained the same way as the costs can (by simply adding the individual category durations), the sum of the durations represents the maximum completion time period required to complete a project. The construction of the project allows some activities to overlap, so the categories may similarly overlap. The rate of overlapping, if any, is up to the contractor to determine. The analysis of this overlapping showed that there could be an exponential relation between the actual project duration and the ratio of straight/actual duration.
Degree
Ph.D.
Advisors
Chang, Purdue University.
Subject Area
Civil engineering
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