Analyzing the causes and impacts of design errors and omissions in highway construction

State Departments of Transportation (DOTs) often face challenges in completing highway construction projects on time and within budget, primarily due to design errors and omissions (E&Os), which lead to change orders and delays. While research has mainly focused on vertical construction, insights into horizontal projects are scarce. This paper employs a mixed methods approach, including change order analysis, surveys, and interviews with experts, to examine the impacts and causes of E&Os in highway construction, revealing varying perceptions among participants. Analysis of 960 change orders over eight years from a US state DOT revealed that design errors and omissions (E&Os) in Design-Bid-Build (DBB) accounted for 14.4% of total change orders, representing 0.22% to 2% of the original estimated annual contract. Although this seemed minor, it resulted in project-specific cost changes of negative 2% to 15% from original budgets, impacting overall project performance. Both design and construction experts were interviewed and surveyed to evaluate the impact of design E&O. Surveys and interviews confirmed that plan errors had the highest impact on cost. This research provides practical insights from a state DOT by quantifying the impacts of common design errors in DBB projects, identifying the prevalent reasons and frequent design errors, and proposing strategies to minimize them based on industry perceptions.