Public transportation services in Chiang Mai city are currently provided mainly based on two types of vehicle; fixed-route mini-bus and non-fixed-route light-truck called “Silor Daeng”. The Local government attempts to change urban public transportation into fixed-route operation service. Due to inefficient non-fixed-route truck, environmental impacts such as air pollution from exhaust gas of vehicles is increasingly becoming a serious problem. LCA is a tool to estimate environmental impacts of product throughout its lifecycle. The aim of this study is conduct Life Cycle Assessment (LCA) to analyze environment impacts from vehicles’ lifecycle including material production, vehicle production and use stages of the two types by a ‘NETS’ methodology and find the environmental cost of silor daeng & mini-bus in suitable route by use the logistics management based on linear programming in terms of internal cost and external cost. As the result, we have found a use stages is main environmental impact more than 70% of life cycle and environmental cost of suitable route from 3 points of view; Energy, Environment and Economy