Review and prospect of research on road traffic flow energy model

Energy is a necessary prerequisite for the operation of road traffic flow. Describing the phenomena of traffic flow from an energy perspective will promote energy conservation and emission reduction technologies. To clarify the application status and trend of traffic flow energy, this paper studies and summarizes the literature on traffic flow energy, classifies the traffic flow energy models into four groups, discusses the benefits and drawbacks and practical scenarios of various models, and suggests future research topics. The research revealed that the ultra-microscopic traffic flow energy model, based on the principle of vehicle energy flow, has high calculation accuracy but is hard to forecast traffic flow energy, which is adequate for estimating the energy of a single vehicle; The microscopic traffic flow energy model, which can predict traffic flow energy but with low calculation accuracy, considers interactions between fleet vehicles and helps evaluate the energy consumption features of various traffic flow states; The average characteristic parameter of the traffic flow is the key to the macroscopic traffic flow energy model, which calculates energy precisely for the uniform traffic flow but lacks the macroscopic traffic flow theoretical underpinnings; The simplified traffic flow energy model of traffic flow has a straightforward structure but the low calculation accuracy, making it suitable for assessing the effectiveness of the traffic flow model. Large-scale vehicle testing, the thorough integration of macro and micro traffic flow theories, and the decrease of computing complexity should be the main focuses of future research on traffic flow energy models.