Validation of predictive production rates using historical data

The Tennessee Department of Transportation (TDOT) is currently using production rates that were developed from past experience and some historical data to estimate contract duration. These production rates tend to underestimate the time duration of a project. Research by the University of Tennessee, Knoxville has developed predictive production rates based on on-site construction operations observed in 1997-1998. The P₉₅ values were developed on the basis that the contractor would complete an operation 95% of the time. Without making any comparisons to past performance, the development of the P₉₅ values was based limited observations. Historical data were collected, analyzed, and used to make comparisons to the predictive production rates. This thesis concentrates on the comparisons of historical data. Historical production rates were determined based on information retrieved from inspector’s diaries, asphalt plant books, field books, and final record books. Comparisons between the historical production rates and the predictive production rates could then be made to determine if the P₉₅ values were applicable The P₉₅ values were then used to estimate the time duration of the twenty-two operations studied and compared to the number of days reported for completion of the operations. There appears to be a large discrepancy in production rate between the historical records and the P₉₅ model. One major reason is the interpretation of days reported. Without sufficient information from the historical records, the days reported were conservatively defined as full days of operation. This interpretation can easily lead to lower than actual production rates.