Public Transport Prioritization Based on V2X

Numerous road traffic authorities and public transport companies are facing the challenge of modernizing existing radio technology used to improve public transport (PT) travel time. In Europe in particular, this transition is becoming increasingly urgent as some of the analog frequencies used for this purpose will no longer be available after 2028. V2X, based on ITS-G5 (IEEE 802.11p) in Europe, is one of the most promising candidates for a replacement. V2X offers the advantage that standardized protocols and components are already available on the market. Some of these are already being installed in vehicles today to increase safety. In addition, there are many local road traffic authorities that are equipping their traffic light signal systems with appropriate communication technology. The necessary test tools are therefore already available and are used for other V2X-based services in addition to the prioritization use cases.

There are still a few hurdles to overcome before a V2X system for PT prioritization can be put into operation. First of all, those responsible for road traffic in the city and the transport companies must agree on V2X as the successor technology. The main question here is whether V2X meets the requirements in terms of communication range. Furthermore, the necessary investments for the technology transition must be approved. In order to create investment security, a suitable test tool can be used at this point to check whether the communication range is sufficient (see illustration). CANoe.Car2x, the V2X test tool from Vector, also supports range measurements with suitable functionality and can visualize the results in different ways.

Once the decision for V2X has been made, cities and municipalities as well as the respective transport company will be faced with mixed operation for a certain period of time. This is usually unavoidable because neither all traffic light signal systems nor all buses and trams will be equipped with V2X at the same time. This applies in particular to bus routes that run beyond the city limits and serve neighboring municipalities. A closely coordinated approach by the project partners is necessary here for the transition phase.

At the latest when the first radio components are put into operation, the question will arise both on the road traffic authority side and at the transport companies as to how the road-side unit (RSU) at the traffic light signal system or the on-board unit (OBU) in the vehicle can be tested for acceptance.

As a test tool, CANoe.Car2x offers the option of assuming the role of the respective communication partner. The data exchange with the device under test (DUT) is bidirectional. This means that CANoe.Car2x generates the real radio communication of the simulated communication partner and also reacts to the messages it receives from the DUT. This means that the respective acceptances can be carried out independently of each other and without taking the deployment status into account.

The following use cases regarding bidirectional communication are possible:

(1) OBU Test

• Simple simulation of the RSU with various sequences (granted, rejected, etc.)
• Special scenarios such as specific states of the RSU
• Scenarios that simulate error cases

For this purpose, CANoe.Car2x can be taken along in the vehicle (equipped with the OBU).

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(2) RSU?Prioritization Function Test

• Typical approach of the (virtual) bus or tram
• Typical approach at different times of a signal cycle
• Repeated approach at longer or shorter intervals
• Special scenarios, e.g. modified approach route due to roadworks or missing cancellation after passing the traffic light
• Approach and prioritization of an emergency vehicle
• Approach of two vehicles competing for prioritization in different combinations (bus, tram, and emergency vehicle) and with different time sequences
• Stress tests with high communication load
• Security tests

In this case, the tests with CANoe.Car2x can be carried out from a parked service vehicle.

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(3) OBU Test During Mixed Operation

• Virtual RSUs at nodes that are not yet equipped with an RSU (e.g. for the acceptance of an OBU in a newly equipped vehicle).
• Monitoring and testing of bidirectional communication between OBUs and real RSUs that are already installed.

For this purpose, CANoe.Car2x can be taken along in the vehicle.

In all cases, it makes sense to record the communication and carry out a subsequent detailed analysis and further tests in the office. Even after project completion, CANoe.Car2x can be used for regular recording and automated testing during operation. CANoe.Car2x is therefore a helpful tool in all V2X project phases.

• More About CANoe.Car2x

Discuss your project with our experts on the upcoming Intertraffic Amsterdam 2024 from April 16 to 19. We welcome you to our stand 05.528 in hall 5 and will be happy to advise you. You can also bring a PCAP logging file with you that is used for a live demonstration in our test tool.