Wireless across road: RF based road traffic congestion detection

Road congestion is a common problem worldwide. Intelligent Transport Systems (ITS) seek to alleviate this problem using technology. But most ITS techniques, currently used in developed countries, are inapplicable in developing regions due to high cost and assumptions of orderly traffic. Efforts in developing regions have been few. In this paper, we seek to develop a low-cost ITS technique to detect congestion in disorderly road conditions. We take Indian traffic conditions as an example for our analysis. But we believe that most of our claims and experimental results can be extended to other developing countries too. Our technique is based on exploiting the variation in wireless link characteristics when line of sight conditions between a wireless sender and receiver vary. Our system comprises of a wireless sender-receiver pair across a road. The sender continuously sends packets. The receiver measures metrics like signal strength, link quality and packet reception. These metrics show a marked change in values depending on whether the road in between has free-flowing or congested traffic. We have experimented with off-theshelf IEEE 802.15.4 compliant CROSSBOW Telosb motes. From about 15 hours of experimental data on two different roads in Mumbai, we show that we can classify traffic states as free-flowing and congested using a decision tree based classifier with 97% accuracy.