A system for relieving traffic congestion of a two-way road, each way of which consisting of a plurality of lanes, said system comprises: means for limiting mobility of the traffic, including three elongate main members of a generally equal length, wherein: one main member is disposed longitudinally on and along median line of the road, for blocking the traffic from moving across said line; the other two main members, each of which is disposed longitudinally on and along a lane line of the road, on one side of the median main member, for blocking the traffic from moving between the lanes, each end of the main members is extended, by an elongate auxiliary member of a shorter length than the length of the main members, transversely across a lane, wherein each transverse auxiliary member converges towards a point on the line adjacent one end of the median main member, for blocking the traffic from moving along the lane; and said main and auxiliary members are capable of being erected and retracted in a coordinative manner. Also disclosed is a method for relieving traffic congestion of the two-way road.