Reliable and secure data communications between cooperative ITS stations such as Road Side Units (RSU) and Onboard Units (OBU) are essential preconditions for implementation and deployment of cooperative systems in public as well as individual road transport applications. Viable applications of cooperative ITS solutions both in public transport and individual road traffic include among others :
- bus and tram priority,
- emergency vehicle preemption,
- road hazard warnings and
- protection of vulnerable road users.
Public transport priority at intersections
Public transport priority requires the intersection traffic light control to be driven by the situation of approaching transit vehicles within the traffic flow. The interplay between MAP messages defining ingress and egress lanes of the intersection as well as turning maneuvers and SPAT messages describing the real-time signal phases and timings enables the OBU to request the desired signal state by an SRM (signal request message) for the appropriate phase according to the route and schedule of the transit vehicle. The ifak C ITS OBU is equipped with a Green Light Optimal Speed Advisory (GLOSA) algorithm to provide advice to the bus driver on preferred speed for passage of traffic lights during green phase. In cases of bus stop locations close to the signalized intersection in driving direction the driver is supported by additional time signals for closing doors and departure from the stop.
Emergency vehicle preemption at intersections
Preemption of emergency vehicles approaching from any direction at the intersection can be realized by additional phases of the control algorithm that are initiated through V2X messages sent by the ifak C ITS OBU in sufficient spatial and timely distance ahead. A typical accident scenario involves right-turning bus traffic conflicts with pedestrians and cyclists at complex urban inter-sections. Collisions between right-turning traffic and particular-ly vulnerable road users are still one of the most accident-prone and often most serious accident scenarios in current traffic. The onboard unit can be connected to a screen at the dashboard of the driver’s cockpit to display warning messages in case of potential collisions. Collision detection software is included in the ifak C ITS OBU software package.
Secure communication by Public Key Infrastructure
An essential precondition for the seamless function of the ITS application cases is the establishment of a secure communica-tion between ITS stations RSU and OBU to ensure both trust and privacy of the communication components. The ifak C-ITS OBU is enabled to guarantee trust and privacy requirements by its capabilities of registration, enrollment and automatic subscription of short and long term certificates from a Public Key Infrastructure (PKI).
Technical specifications
CPU and Interfaces
- CPU Apalis iMX 6 X 8 quad core, Linux 4.14.173
- ITS-G5 over WLAN 802.11p at 5.9 GHz
- WLAN 802.11 a/b/g/n
- Bluetooth LE and cellular 4G SIM slot
- Ethernet (M12), USB (A,B), GPIO, CAN, IBIS (VDV300)
- Audio/Video display socket
Antennae with FAKRA sockets
- 1 WLAN 802.11 a/b/g/n wireless communication
- 2 ITS –G5 (WLAN 802.11p) for V2X communication
- 1 cellular 4G/LTE antenna
Aluminum casing with passive cooling
- Dimensions 162x105x50 mm
- Power supply 24V (ISO 7637), < 5W, (max. 300 mA)
- Weight 1550 g including cabling and antennae
Certificates for public transport use
The ifak C ITS OBU has been approved in certification processes for use in public transportation vehicles of railway rolling stock and busses for compliance with the following regulations:
- Fire protection inspection report according to DIN EN 45545-2:2020 for rail vehicles
- Electromagnetic compatibility test report according to UN/ECE R 10 for bus vehicles
- Electromagnetic compatibility test report according to EN 50121-3-2:2016 + A1:2019 for rail vehicles