A comparison of impacts derived from the road executive project, and the works during construction was performed.•
Executive projects based on incomplete studies require adjustments in the executive project during road construction.•
Adjustments of the executive project account for 16% average increase of environmental impacts of road construction.•
Increase of environmental impacts derived from miscalculations in location of borrowing areas and quarrying volume.•
Adjustments of the executive project accounts for 30% of costs overrun of road construction.
Road infrastructure works are complex and important undertakings for the social and economic development of a country. They are based on studies that ensure the technical, environmental and economic feasibility of the work. These studies are the basis of the road executive project, which includes the projects that characterize the work to be performed. Road constructions can be considered as horizontally arranged, integrated and complementary activities, so that each of them establishes boundary conditions that affect all the others. Thus, modification of any part of the project changes the proposed scenario for the execution of the following work stages. Most executive road construction projects must be readjusted during the construction because of deficiencies and incomplete surveys and field studies. Those modifications extend the construction period of the road, alter the contractual value and the environmental impacts of the work. This paper investigates the environmental impacts, associated with the input and output flows, as well as the cost overruns of the construction of a road, considering the activities foreseen in the awarded project (scenario S1) and those executed by the construction company (scenario S2) using a Life Cycle Assessment (LCA). The adjustments done in scenario S2 accounted for an average increase of 16% of the environmental impacts in relation to S1 impacts. The critical stages of those activities were clay mining, embankment construction, base construction, and paving. Although the clay and soil volume moved in the construction process was five-fold higher than the volume of aggregate material, the impacts of the exploration and processing of the rock aggregates were 27% higher. Comparing the costs of both S1 and S2 scenarios, the final contractual values of scenario S2 were average 30% higher than the scenario S1 projected costs. Specifically, the S2 costs of earthwork and paving stages were 45% and 11% higher than S1 respectively. The ground of cost overruns and delays during construction are forecasting errors for soil movement and usage of rock aggregates. The results also shown that LCA application after to completing the executive design of a road can help road designer and contractor during the decision-making processes, to anticipate the potential environmental impacts that road construction can produce, as well as predict the environmental effects of changes on the executive project.