SUMMARY
This paper presents a comprehensive model with an application of discrete-event simulation (DES) that facilitates an estimation of CO2 emissions resulting from equipment operation in flexible pavement construction. While there are a number of past studies applying a DES technique to the construction process, they mostly concentrate on a single process rather than an entire project. The constructed model aims to improve the current body of knowledge in two aspects: (1) the development of a comprehensive construction operation diagram representing flexible pavement construction and (2) the application of DES that contributes to a more reliable result of the environmental impact. An application example of the real expressway project in Thailand was analyzed to demonstrate the use and capabilities of the developed model in evaluating the environmental impact in terms of CO2 emissions. The findings will provide a holistic environmental perspective to transportation planners and help them in analyzing their resource allocation in order to make the projects more eco-friendly.