The highway network in Turkey spans 3,523 kilometres (km) as of the end of 2020 (Turkey Ministry of Transport and Infrastructure, 2020). To support the growth of this network, the country has implemented some of the most advanced technologies in tolling, including passive UHF RFID technology. Over 600 high-performance UHF RFID readers have been deployed. The implementation of passive UHF RFID technology has greatly reduced congestion and improved cost-effectiveness. In this case study, we will look at how passive UHF RFID is being implemented, the technical challenges, and how these challenges were overcome.
Turkey’s network of toll roads consists of a combination of Multi-Lane-Free-Flow at high vehicle speeds, Open Road Tolling at low-speed roads and Stop-and-Go Toll Plazas. The traffic condition varies from high-speed free flow to bumper-to-bumper traffic. Take Istanbul as an example, the average peak hour traffic speed at 27 km per hour and time lost in congestion during peak commute periods compared to free-flow conditions is 45 hours in 2020 (INRIX, 2021).
Currently, Turkey runs passive UHF RFID and Dedicated Short-Range Communications (DSRC) tolling systems in parallel. Passive UHF RFID transponder identification is captured and forwarded to the backend system where it is verified against license plate images. The country started implementing passive UHF RFID solutions about 10 years ago.
Compared to DSRC transponders, passive UHF RFID transponders are less expensive, smaller, typically a label; therefore, easier to fit into vehicles. They also eliminate the administrative and logistics costs related to the issuance of DSRC transponders. In addition, the new passive UHF RFID readers offer features to ensure that the tolling operators have the stability and accuracy required to keep traffic flowing safely at optimal speed and improve operational efficiencies.
While passive UHF RFID is a proven technology for Automatic Vehicle Identification (AVI), with bumper-to-bumper traffic and the narrow frequency band (865.6 – 867.6 MHz), with reduced power compared to the level authorized in the United States, it is not easy to reach the vehicle identification accuracy target. Moreover, the extreme weather conditions in Turkey also pose a challenge.
Tetra HGS, a world-leading Vehicle Identification and Electronic Toll Collection Solutions Company, have been working with Litum Technologies, a global leader and provider of Automatic Vehicle Identification (AVI) Technologies and Intelligent Transportation Systems (ITS), to deploy the new generation of passive UHF RFID system across Turkey’s toll road and bridge systems.
According to Alp Ülkü, Director of Business Development of Litum Technologies, equipment specification, performance, quality, and reliability were some of the most important factors to consider when choosing the right equipment for this project. Litum Technologies decided to partner with Star Systems International (SSI) to supply the equipment because of SSI’s expertise and commitment to ensure customer success.
The Titan Reader was selected for this project. Titan is a high-performance smart RFID reader. It is designed for high demand vehicle identification and tolling applications, such as Multi-Lane Free Flow. In addition, Titan comes with an IP67 case and has an operating range of -40°C to +70°C (-40°F to +158°F). Most Titan Readers are deployed at Multi-Lane and/or Non-Stop sections of the country’s highway and toll roads with an overhead gantry and antennas capturing transponder identities at speeds of up to 120 km per hour.
The Obstacles and The Solutions
This section discusses a few technical obstacles encountered during the initial deployment and how these obstacles were addressed.
Obstacle 1: Interference
Given the frequency band requirement, the team only has about 2 MHz to work with. In addition, this 2 MHz space does not belong to electronic toll collection exclusively; it is shared with any other technology that uses an unlicensed transmitter. One of the biggest issues to solve is interference, which could greatly affect the system’s performance.
Solution: SSI’s Titan reader conducts an over-the-air analysis of the environment and adapts to it dynamically for optimal performance. Titan actively listens to co-channels and adjacent channels and decides how to maximize throughput and communication patterns. This cognitive algorithm allows Titan to reject interference and maximize reading performance.
Obstacle 2: Accurately Identifying Vehicles
With traffic and vehicles that are bumper to bumper, side by side, changing lanes or next to buses or trucks, the more reliable reads toll operators can get while in the read/transaction zone, the higher the chances of a successful transaction. For instance, taller vehicles, such as trucks and buses, cause problems in the reading sequence as they move closer to the read-zone because they might block smaller cars. In addition, flat windshields of buses can create a challenge regarding tag transmission orientation. With Multi-Lane-Free-Flow and Open Road Tolling at high speed, vehicle identification gets even more challenging.
Solution: Titan reader tracks transponder reads from moving vehicles by determining lane position and identifying vehicle location. Together with optimized system settings, antenna orientation and lane setup, SSI’s overall design of the system creates an optimum read zone. Therefore, the system can accurately identify close and fast-moving vehicles and prevent cross-lane reading.
Obstacle 3: Irrelevant Reads
There are many non-tolling transponders on the road, e.g., tags on goods or packaging carried by the vehicles.
Solution: SSI Titan reader features a Text Stream Interface (TSI) which allows operators to run text-based commands. In this case, the “Select” command is used to filter out non-tolling tags.
Obstacle 4: “Missing” Transactions
During the initial implementation, it appeared that the system had missed a number of transactions.
Solution: Assuming the settings and antenna orientation are correctly set, the percentage of missing transactions is minimal. SSI’s support team was able to quickly narrow the issue down to the placement of passive UHF RFID tags. Since most drivers in Turkey were used to DSRC transponders, which could be placed in the glove compartment, they did not understand how to properly attach the passive UHF RFID. The toll collection company was advised to provide clearer instructions to drivers so that they can properly affix the passive UHF RFID tags.
The new system gives a success rate of approximately 99.5%. In addition to cost-saving, improving reliability and transaction efficiency, the biggest benefit of this new passive UHF RFID system is the reduction of congestion. True Free Flow of traffic was enabled by the implementation of the new passive UHF RFID system. Multi-Lane-Free-Flow and Open Road Tolling reduce congestion time and carbon emissions. According to the Global Traffic Scorecard issued by INRIX, Istanbul was ranked the 33rd most congested city globally compared to the 4th in 2019. In addition, there was a 70% decrease in hours lost due to congestion in 2020 compared to 2019 (INRIX, 2021).
Turkey’s highway network is expected to expand to 8,247 km by 2035 (Turkey Ministry of Transport and Infrastructure, 2020). More SSI readers are expected to be deployed as part of the expansion.
Arman, M., & Kayaci, K. (2017, November 7). Functioning & Financing of National Road Management in Turkey [Slides]. UNECE. https://unece.org/DAM/trans/doc/2017/TEM/2017/Turkey.pdf
INRIX 2020 Global Traffic Scorecard. (2021, March). INRIX, Inc. https://inrix.com/scorecard#scorecard-report
Turkey Ministry of Transport and Infrastructure. (2020, August). Highway Constructed by Year. https://static.poder360.com.br/2019/02/INRIX_2018_Global_Traffic_Scorecard_Report__final_.pdf