Performance study of inter-vehicle information dissemination using long range wireless system for assisting congestion resolution at sags

Sags are road sections where gradient slowly changes from downslope to upslope, being mainly found in expressways. It has been observed that some drivers are not aware of speed decrease due to grade resistance at sags, and as a result congestion occurs. For velocity control to mitigate the congestion, the theory of Jam Absorption Driving (JAD) has been attracting attentions which encourages vehicles running behind the congested platoon to reduce their speed and to delay arrival to the platoon. The authors have presented velocity control system that utilizes inter-vehicle communication with long range wireless system such as 700MHz ARIB-T109 for quickly sharing congestion information among cars and leads cars approaching the congested platoon to perform JAD. This paper evaluates the proposed scheme by focusing the effect on the communication range of wireless system on the congestion alleviation performance. The simulation results show that using communication range of 1km has substantially reduce the travel time of the vehicles compared to using small communication range such as 300m and information is relayed among cars with multihop broadcast. Also, this configuration is effective for the case where only low ratio of vehicles are equipped with communication systems. The findings of the paper show that the proposed scheme is beneficial to improve traffic flow at sags.