Transport of modern worldwide cities generates harmful emissions that accounts for nearly half of the total pollution in urban areas. Therefore local governments are forced to stimulate appearance of new fuels and technological innovations in urban mobility. Nevertheless there is a lack of methodological tools for supporting decision makers in spheres of motivation for using green vehicles by drivers and allocation available green capacity. This paper is devoted to the problem of green and non-green traffic flow assignment on the network consisting of green and non-green routes. The approach of defining green routes (green subnetwork) which are fully loaded and provide less travel time for green vehicles are developed. Conditions of well-balanced green subnetwork are obtained explicitly for the network of parallel routes.