Brno - a complete V2X system

Our flagship project showing almost a full spectrum of V2X use-cases. The largest public transport priority system in Europe was just a part of it...

Internationally appreciated showcase of V2X

The projects in Brno are one of the best examples of V2X deployment in Europe and we are proud that we contributed in such an important way to them. It was not a coincidence that Brno was selected as the place of the C-ROADS conference in 2021.

Four projects working together


The complete system in Brno was build as a result of 4 tightly integrated projects:

We played a key role in all of the project and for three of them we were the only supplier. Currently, there are about 900 vehicles with OBU and 130 RSUs in and around Brno.

Public transport priority


Since 2018, we have equipped about 800 public transport vehicles with OBU units (and of it 750 in 2018). They are:

  • 350 trams,
  • 300 buses,
  • 150 trolleybuses.

The OBU is tightly integrated with the board computer, also developed by Herman.

Road-side units

Since 2018, we have equipped about 90 intersections with our RSU. The RSUs are of two types:

  • With a full use-case support, including emergency vehicle priority. Connected to new traffic light controllers (TLC) by Cross.
  • Only with public transport priority support. Connected to an older TLC of any vendor – shown on left

The use of the RSUs which only support public transport priority allowed to replace an older public transport priority system.

Public transport priority in general

The system in Brno features the following:

  • SREM and SSEM communication – the OBU addresses a particular intersection and indicates the correct ingress and egress approaches.
  • The confirmation from the traffic light controller (TLC) is shown in the board computer.
  • Ability to address two or more intersections at the same time.
  • Ability to inform the TLC about the vehicle plans (stops at a station before and intersection or just passes).
  • Forwarding of V2X packets
  • High performance – up to 1000 vehicles per day at a single intersection.
  • High reliability – less than 5% V2X packet loss from the first login position.

Transition phase from the older system

Our solution in Brno enabled transition from an older analogue radio system to V2X – without any interruption of the prioritization.

This was achieved thanks to parallel operation of older radio and V2X in vehicle. Our board computer was able to control priority using the older system, while at the same time providing necessary data to the OBU unit.

The RSUs delivered had a very special feature: they were able to communicate with the traffic light controller exactly the same way as the analogue modem did. That is, they pretend to be an “analogue modem”. For the traffic light controller nothing changed and even no traffic control algorithms had to be changed. The oldest controller to which an RSU was connected was 25 year old – and the priority worked.

Our solution thus allowed the city of Brno to switch from analogue radio to V2X at a comparatively low price with no change in the traffic controllers.

Emergency vehicle priority

Currently, all first-response fire brigade vehicles are equipped with OBUs (currently about 20). This allows them to get to their destination faster and safer. The range of V2X proves to be sufficient in most cases.

The units are also connected to a PKI, so the communication is secured. In addition to getting priority, emergency vehicles are warning other drivers using V2X.

Apart from the fire brigade, ambulances are now testing priority in the city.

Fire brigade vehicle in Brno