DEVELOPING HIGHWAY CONSTRUCTION PRODUCTION RATES OF WISCONSIN DEPARTMENT OF TRANSPORTATION
Project contract planned completion time is usually one of the most important and challenging things to determine when preparing highway construction contracts. Over the past few decades, the construction process and the construction output changed dramatically as a result of the technology improvements faced by this industry. Both the importance and process of estimating highway construction time have increased in significance as roadway user costs themselves have become more significant. However, the highway construction industry is one of the sectors with little or unreliable data available for estimating productivity. This is why the productivity estimation tool developed by this study is of crucial importance for designers. For the purpose of this study, the factors affecting productivity were identified and divided into two main categories: project specific factors and contractor specific factors. The different techniques and sources used to predict productivity were also identified through an extensive literature review. The research team also looked at the construction activities, the productivity rates and the methodology used by other departments of transportation (DOTs) in the United States. The top 10 project expenditure items were also identified based upon 2010 and 2011 WisDOT projects. In addition, quantities were evaluated for major work items by looking at projects that were completed over the last 3 years. Because of the various factors affecting construction productivity rates, it is almost impossible to account for the impact of all of them and it is impractical to collect a sufficient number of data points to make such analysis feasible. The main challenge of this research was the data collection phase. Productivity data that contractors were requested to provide is considered confidential and one of the main sources of providing a competitive advantage in the construction industry. Thus, those that have a historical record for this kind of data were reluctant to share it. In addition, some companies don?t follow a formal process to track and collect actual project progress and expenditures, so couldn?t provide it. Though there were challenges faced during data collection, this research will enable users to update the productivity rates of earthwork, concrete paving, asphalt paving, bridges and structures as well as some other miscellaneous construction activities for highway projects in Wisconsin by obtaining production data from actual construction projects. The scope of this project was to review the current production rates as provided in the Facilities Development Manual (FDM), recommend additional items and updated rates where appropriate, and develop a methodology for capturing a database of production rates on future projects. The main contribution of this study to the construction industry in general and the Wisconsin designers in particular consists of a tool that the designers can use to get a good estimate of the productivity rates for a specific project taking into account its job conditions. Guidelines on how to use and update the tool are also provided in this report. The data obtained were analyzed using a forward stepwise linear regression technique for each of the dependent variables (productivity rates studied) considering all of the independent variables (influencing factors). This kind of regression was used to identify the main factors that affect the productivity of each activity and to account for these specific factors when predicting productivity rates for future projects. After identifying the most appropriate independent variables for each of the dependent variables, a final multiple linear regression model was generated and its residual standard error was obtained. The statistical results obtained from the analysis of the responses were used as a basis for the productivity estimation tool developed. Finally a database was created where project personnel can input production rates observed on WisDOT projects so that a historical record is available to provide a basis for updating the published production rates.