Second Conference of Junior Researchers in Civil Engineering 11 Applying RFID in traffic junction monitoring Nikol Krausz BME Department of Photogrammerty and Geoinformatics, e-mail: krausz@mail.bme.hu Abstract Improving road safety is one of the major issues in the transportation policies of most countries. This paper presents traffic monitoring and classification technique in junctions. The RFID-based monitoring system can be used in case of every crossing types. This is a human error and intervention-free system, which is able to provide different types of traffic data. The same system is also capable of detecting vehicles traveling against traffic direction. Introduction The sale of new motor vehicles shows an increasing tendency worldwide; the newly purchased vehicles also have to use the congested existing road networks that in most cases cannot cope with the increasing volume of traffic. Since for some reasons the public road networks cannot be repaired (e.g. lack of funding), congestion arises. A major issue of traffic management is how to effectively reduce the number of road accidents. The growing number of vehicles involved in road traffic results in high number of fatal accidents especially in less developed countries. The reason of accidents, their severity and location are important statistics for the transport engineers. Accidents can happen for several reasons, the main types are [1]: inattention, drowsiness, weather conditions, the unavoidable reasons e.g. pedestrian runs across, traveling against traffic (ghost driver). In order to protect human life the governments prioritize the development of road infrastructure primarily by building redesigned junctions. Other tools include reduced speed zones, changed traffic directions and additional. In areas where accidents occur, traffic lights can control the flow of vehicles. Where the surrounding environment allows, the conversion of conventional junctions to roundabouts can also be a solution. An important aspect of all methods is to improve safety and to exploit the capacity of the network at the same time. Junction monitoring Traffic is coming from different directions into the junction and leaving it based on the traffic rules. The intersections can be classified according to their spatial features, whether it s a level crossing or a separate level crossing or it includes railroad crossing or not. Traffic flow observation of a particular junction is possible with different techniques. Among them, the easiest way is the conventional manual traffic counting, by observing the selected area and collecting the necessary data in a form. This solution is accurate and can be used in any kinds of junctions that are not equipped by sensors capable of monitoring traffic. Such traffic counting campaigns provide only data that is valid only on the particular time period when the measurements were carried out, however, there are mature methods to extrapolate the results. In contrary, a fully automated system is able to continuously provide constant flow of data, regardless of weather, without the possibility of human error. Over the years, the traffic experts were already developed a number of solutions to observe the junction. The technology I present is used in medical applications to logistics to many other areas. The system is used radio frequency for data communication. RFID components Radio frequency identification (RFID) is a radio based communication technique originally developed for
Second Conference of Junior Researchers in Civil Engineering 12 identifying airplanes in the World War II ( friend-or-foe system). The technique is already used also in transportation (e.g. cargo logistics), but is still considered as new technology in the field of safety-related applications. The RFID system consists of reader and tags. Both reader and tags are equipped with antenna. Data is transferred between a tag and a reader via low-power radio waves. (see Fig.1.) In communication between reader and tags the most applied frequencies are the following: LF (low frequency): 125-134 khz HF (high frequency): 13.56 MHz UHF (ultra high frequency): 868-956 MHz Microwaves: 2.45 GHz. Fig. 1. RFID system components RFID readers are devices that convert radio waves from RFID tags into a form that can be passed to the processing software. An RFID tag reader uses antennas to communicate with the RFID reader. Detailed description of the system can be found in [2] and [3]. Monitoring system structure The simplest RFID system configuration in transportation applications is as follows: at least one reader is deployed on the roadside (e.g. onto the guardrail, traffic sign pose, motorway bridge) and tags are mounted on the vehicles in certain locations avoiding their electromagnetic shadowing. Tags are moving, whilst the reader is in fixed location. A tag can be read many times while being in the range of a reader, each identifier has to be recorded only once. The number of reads obviously depends on the travelling speed; in urban areas there is more chance to sense a tag more than once. On a motorway/highway, because of the higher speed, the number of detections is lower. The roadside RFID reader senses the approaching tags, and receives their identifiers, in theory, all moving vehicles in the range of the reader can be sensed by the system. The traffic volume can be derived based on the number of the crossing vehicles in a particular period of time. Figure 2 shows the communication between tag and reader in traffic. Specific data can be stored in each individual tag that can be downloaded by the reader, if it not only scans the tags, but also reads the data stored. These stored data can be different types of car-dependent information, such as vehicle type, engine size, fuel type, curb weight, total emission, special/dangerous cargo, emergency vehicle etc. (see Table 1.). Using these data more accurate traffic statistics can be derived. The collected data are transmitted by wired or wireless communication to a central server. In practice, data security and privacy issues have to be handled carefully not allowing to track individuals or collecting any kind of sensitive information.
Second Conference of Junior Researchers in Civil Engineering 13 Provided data Fig. 2. The reader and tag communication The processed, result data are depending on the primary user needs, all provided data is based on the information, which stored in the tags memory. Optimally, every tag contains all the typical information about the vehicle that carries it. In this case, during a comprehensive junction monitoring all types of the passing vehicles can be recorded. From this data, information noise pollution of the selected junction can be derived or it can be stated whether the selected junction is a preferred transit way of the trucks, or not. The daily traffic flow-through data can be summarized and processed, this can be quantified for the selected junction. Beside the type of vehicle the axle load and weight data can also be stored in the tags memories, therefore information on pavement load and road condition can be calculated. This kind of road pavement monitoring can support road maintenance work and future traffic planning. Applying multiple readers in a single junction and recording the time-stamps of passing tags enable to derive velocity. By acquiring such temporal data, information on the level of congestion can be obtained. In long distances, e.g. by using such system on the motorways the average speed of a vehicle can be recorded, therefore it also can be used by the law enforcement. date time(h:m:s) tag Id db fuel type total emission CO2 (g/km) axle load total weight (kg) 20120307 152156 200109738-50 diesel 126 475 970 20120307 152156 200142308-46 petrol 111 515 1030 20120307 152156 200142309-49 petrol 348 1133 2166 20120307 152157 200109794-61 petrol 290 813 1625 20120307 152157 200109795-47 diesel 900 3600 7200 20120307 152158 200109798-52 petrol 194 715 1430 Ghost driver tracking Table. 1. Sample raw data The number of reports of drivers travelling against the right traffic direction (i.e. wrong-way drivers (see [4]), also known as ghost drivers) is increasing (more than 500 in a year in Austria and about 1800 in Germany [5], [6]). Due to high speed of traffic, if a vehicle enters the motorway from the wrong direction, the chance of mass and fatal accident is extremely high [7]. In urban environment the speed is lower, however, the collision cannot be always avoided due to lack of space. The main causes of ghost-driving: suicide attempt
Second Conference of Junior Researchers in Civil Engineering 14 ignoring traffic signs tiredness bad weather conditions, poor visibility intended entry: o proving courage o short cut to reduce travel time. The goal of a ghost driver system is to warn the road users as early as possible if there is a moving vehicle against them. Such rapid detection system can be supported by the RFID technology by deploying RFID readers on the roadside. Figure 3 shows a vehicle moving wrong way in a sample junction (see Fig.3.). The roadside readers are scanning the traffic of the crossroads, the vehicle moving in the wrong direction passes at least two detection points. Therefore based on the sensing order it can be decided whether the direction is correct or not. If only one reader detects the tag ID, only presence information can be derived, detailed description of the system can be found in [8]. Our initial experimentations proved that using long range (up to 100m) active RFID tags, traveling directions can be obtained, thus the system is capable of detecting ghost drivers even in high speed, motorway environment. Conclusions Fig. 3. Ghost Driver The paper presents a method of monitoring traffic in a junction by radio frequency identification. The RFID system can be found a wide range of logistics applications; the current paper describes how the system is able to provide location data. The system has the advantage of fast data collection and reporting, which obviously works only with vehicles equipped by RFID tags. Assumingly, in the near future all vehicles will carry such tags that can also replace the license plates or car registration cards. Since the RFID technology is standardized, it can be used all over the world. Deploying multiple readers in a carefully planned constellation in a traffic junction, the radio frequency identification is suitable for special tasks, e.g. detecting vehicles traveling against traffic direction. Based on the initial experiences, future research includes RFID antenna optimization for selected junctions.
Second Conference of Junior Researchers in Civil Engineering 15 Acknowledgement The work reported in the paper has been developed in the framework of the project Talent care and cultivation in the scientific workshops of BME" project. This project is supported by the grant TÁMOP- 4.2.2.B-10/1--2010-0009. References [1] http://seriousaccidents.com/legal-advice/top-causes-of-car-accidents/ [2] Krausz, N., Barsi, Á.: "RFID technology: a new tool for positioning", Geomatikai Közlemények, X, p. 99-106, Sopron [in Hungarian] (2007) [3] Finkenzeller, K.: "RFID handbook", John Wiley and sons, Chichester, (2003) [4] https://en.wikipedia.org/wiki/wrong-way_driving [5] https://www.kfv.at [6] https://www.adac.de [7] Safespot D2.3.2. Final Report (2008): http://www.safespot-eu.org/deliverables.html [8] Barsi Á., Lovas, T. Krausz, N.: "Detecting Ghost Driver by RFID", Geomatikai Közlemények, XII, p. 211-216, Sopron [in Hungarian] (2009)