Incentive/disincentive clauses (I/D) are designed to award payments to contractors if they complete work ahead of schedule and to deduct payments if they exceed the completion time. A previously unanswered question is, “Did the costs of the actual work zone impacts that were avoided justify the incentives paid?” This paper answers that question affirmatively based on an evaluation of 20 I/D projects in Missouri from 2008 to 2011. Road user costs (RUC) were used to quantify work zone impacts and included travel delays, vehicle operating costs, and crash costs. Conditions during construction were compared to after construction. Delay costs and crash costs were computed using published data. For every dollar paid in incentives, approximately 5.3 dollars of RUC savings resulted from the use of I/D. Also, I/D projects had a higher on-time completion percentage and a higher number of bids per call than average projects. However, I/D projects resulted in 4.52% higher deviation from programmed costs and possibly more changes made after the award.