PURPOSE: To make a vehicle travel along an alignment of a road only by paying a driver's attention to a movement of the vehicle in front of the driver by providing one side head part of two pieces of tracks on which the vehicle intends to travel in a groove type and making the other in a flat shape.

CONSTITUTION: To a territory of little demanded traffic volume, a two-way one lane road is applied, and for increase of the demanded traffic volume in the future, a two-way two lane road is made by extending a meeting and parting part of the road. Additionally, by making one side head part of two pieces of tracks in a groove type shape and the other in a flat shape, various kinds of vehicles different in distance between left and right wheels are made stable to travel. Consequently, it is possible to apply it to a territory long in distance between interchanges or between ramps by way of making it in a perfect incoming and outgoing restricted state.