Using contractor bid amounts to estimate the impact of night construction on cost for transportation construction

Many studies have documented the merits and problems of nighttime work for highway construction. Most of these studies have examined the safety of the construction site for workers or the traveling public. Illumination standards, sign requirements, and crash rate data have been studied to determine whether crash rates increase during nighttime hours, and the reasons for these crashes. Few studies have addressed either the effects on cost or productivity that nighttime construction has on a project. This study used hard bid unit prices to focus on the effect that performing certain construction activities at night has on cost and productivity. Specifically, the study assumes that a contractor's bid amount reflects expected relative project productivity and answers the question, "What impact, if any, does night work have on construction productivity and therefore bid price?" This is the first paper to answer both questions as related. Among the results was the fact that for the most part, the owner would have saved millions of dollars by allowing the contractor the option of working at night or during the day, though some items were bid lowest if the contract allowed for night work only.