Under the background of China's "One Belt One Road" construction, Cambodia's transportation infrastructure is backward, which restricts economic development in all aspects. Combined with the actual demand of the Cambodian government's plan to build the new phnom penh international airport in Kampong Chhnang, the construction of the expressway project from phnom penh to Kampong Chhnang will break the history of no expressway in Cambodia, which is the demand of promoting the "four-corner strategy" and the need of the economic development of Cambodia. Highway traffic volume is the reflection of economic and social development to highway traffic demand. Its occurrence and development are closely related to the economic and social conditions along the road. Traffic volume prediction is the basis for determining the construction scale and technical standards, as well as the basis for economic evaluation and financial analysis. In order to solve the problem of weak basic traffic research in Cambodia, this research analyzes and predicts the traffic volume of phnom penh to Kampong Chhnang airport expressway project. Key words: “One Belt One Road” construction; Cambodia; Traffic forecast

CICTP