Persistent Surveillance System for Gathering Comprehensive Road Information using Aerial and Land Based Sensors

Road infrastructure in countries like India is expanding at a rapid pace and along with it the need to build and maintain a comprehensive road information system (RIS). Even though static information like road names and road geometry can be collected by a one-time survey, road characteristics like road condition, traffic density, directionality, surface type etc., keep changing over time, posing a challenge to maintain an up to date RIS database. The common satellite based approaches are not sufficient to cover a number of road characteristics. Current ground based data collection schemes are either not affordable due to the use of expensive equipment or not scalable due to its time consuming paper-and-pen data collection approach. This necessitates the search for alternative technologies for road data collection. New systems need to be built using such technologies, which integrates information extraction methods and algorithms best suited for road data collection. Unmanned aerial vehicles (UAVs) are increasingly being used as a low altitude remote sensing platform. Providing cheap, on-demand high resolution aerial imagery and video makes them a unique data collection platform when compared to satellites and big aircrafts. An innovative data collection scheme that utilizes the trajectory information of the moving vehicles from the aerial video of UAVs, to robustly extract road characteristics like road traffic density and directionality has been proposed. The road directionality extraction procedure correctly extracted all node to node directionality attributes on the final evaluation dataset. Also the road density estimation procedure produced the density estimates with a least error percentage of 5%, strongly contending for the use of UAVs in road data collection. Another technology that has the potential to be used as a tool for extensive data collection, is the smartphone. The availability of a number of sensors, networking capabilities and being ubiquitous make them an ideal data collection platform. A smartphone based prototype system MAARGHA, was developed to collect road condition and road surface type. MAARGHA has been tested across different road conditions and sensor data characteristics to assess its potential applications in real world scenarios. The developed system achieves higher information levels when compared to state of the art road condition estimation systems like Roadroid, while achieving road surface type classification accuracy range of 60% to 100%. While the proposed aerial and ground based systems have initially targeted the collection of few road characteristics, they can be extended further to collect many other data as well. Together, the systems provide a unique solution which is more feasible to be used for extensive and frequent RIS data collection. Hence they can be called as persistent surveillance systems. Such data collection infrastructure for RIS can have significant impact on road transport domains like the road infrastructure management, autonomous vehicle navigation, and intelligent routing services. Table of