Impact of Inaccurate Engineer’s Estimated Quantities on Unit Price Contracts

Abstract

This paper discusses the issue of unbalanced bid prices in unit price highway contracts. It analyzes the reasons contractors unbalance their bids and looks for ways that allow public transportation agencies to discourage this practice. It reviews the results of a study of quantity estimating accuracy of 462 transportation projects in Oklahoma, and finds that one method to reduce unbalanced bid prices is for the agency to ensure that the bid quantities used in the engineer’s estimate are as accurate as possible. Doing so reduces the need for contractors to unbalance to protect fixed costs and target profit on bid items that will underrun the quantity used in the engineer’s estimate.