Traffic management, road network planning and appraisal are highly dependent on effectively assessing the performance of existing and future road infrastructure. In traffic engineering, performance assessment has been underpinned by a grading system known as the “Level of Service” (LoS), which identifies performance criteria that reflects the functionality of the road. This study develops a novel, consistent calculation methodology, the Demand Weighted Level of Service Estimation (DWLE) method, to estimate singular holistic multi-modal LoS metrics, which can be used to compare and contrast the performance of road segments. The generalized approach is independent of the definition and quantification of LoS indicators which offers global application potential. A demonstration of the approach provides evidence for the robustness and consistency of the approach. The value of the DWLE method is that it offers a tool for project prioritization evolving a long-held traffic engineering concept of the Level of Service.