Two Ways to Refit Vehicles in Public Transport
12 Jan, 2023

With increasing data volume and requirements for real-time data in public transport vehicles, IP-based communication has become a basic requirement for modern IT system architecture in vehicles. We use two examples to show how transport operators are making the transition from an outdated technology to a modern IP infrastructure 

How to refit public transport vehicles

Why the Shift to IP is Absolutely Necessary

Analog technology with serial interfaces is not designed to transmit large amounts of data. In addition to bandwidth, IP-based communication also offers other advantages such as distribution, standardization and flexibility of the system.

Arguably, the biggest challenge of digitalization is to make large amounts of data manageable. Data should be exchanged quickly, efficiently and according to fixed standards. In addition, the networking of a large number of participants from different locations should be considered. This requires an efficient network infrastructure.

To meet the requirements of such complex data networks, the IEEE802.3 network standard, also known as Ethernet, has become established in recent decades. The standard enjoys great popularity primarily because of its robustness, scalability, bandwidth and degree of standardization. Standardization not only includes fixed specifications for transmission, but also enables compatibility of devices, cables and connectors.

The transformation to an IP-based, digitized public transport vehicle can take place in two ways. In practice, transport operators opt either for

a) continuous retrofitting by purchasing new vehicles or

b) retrofitting the existing fleet.

The following criteria are decisive for the choice: Size of the fleet, deadlines, financing, technical requirements.

Continuous Refit through the Procurement of New Vehicles

One option for retrofitting is the continuous procurement of new vehicles. Depending on the size of a transport operator, about 10% of a bus fleet is renewed every year. Depending on the political climate targets for CO2 neutrality, this quota can also be significantly higher. When buses are procured, they are put out to tender in such a way that they are already supplied by the vehicle manufacturer with an integrated IP network infrastructure including Ethernet switches and cables.

This approach offers the following advantages:

  • The changeover is continuous: the transport operator can familiarize itself with the technology in the new vehicle and take care of the necessary IT infrastructure and specialist personnel.
  • The additional costs for an IP network infrastructure, consisting of Ethernet cabling and Ethernet switches, usually account for less than 0.5% of the total cost of the vehicle. In return, the new vehicles are prepared for future applications and do not have to be retrofitted.
  • No large financial resources required

Continuous retrofitting has one key disadvantage: its duration. Assuming a renewal rate of 10% per year, the retrofit will therefore take 10 years. During this time, two different systems – analog and digital – may have to be operated. This type of continuous retrofit is particularly suitable for transport operators who have enough time with the changeover to realign their operations, recruit new specialist staff and get to grips with IP-based systems.

Retrofit: the Fastest Way to a Digital Fleet

Retrofitting the existing fleet is the fastest way to IP-based communication in the vehicle and thus to digital data.

To ensure that the retrofit is successful, the transport operator sets up a project and puts the network infrastructure out to tender separately. Precise planning of individual phases and cross-departmental collaboration between IT infrastructure, vehicle technology and the workshop are the key success factors.

With regard to the network infrastructure, four steps are necessary for successful implementation.

1. Network concept

  • Define network requirements
  • Select network components
  • Test the concept in the laboratory
  • Finalize configuration specifications for the network

>> Learn more in this article: Network Infrastructure in Public Transport Vehicles: Proof of Concept

2. Pilot operation

  • Initial installation in a few vehicles
  • Testing and optimization in mobile operation
  • Preparation for rollout

>> Learn more in this article: Network Infrastructure in Public Transport Vehicles: Pilot Phase

3. Rollout

  • Ensure scheduled component installation
  • Put network infrastructure into operation
  • Check all participants for function

>> Learn more in this article: Network Infrastructure in Public Transport Vehicles: Rollout

4. Operation

  • Line operation works as expected
  • The network infrastructure is maintenance-free
  • In case of malfunctions or network extensions, replacement of devices or updates is possible

>> Learn more in this article: Network Infrastructure in Public Transport Vehicles: Operation

Depending on the size of the transport operator and the number of vehicles, the process of retrofitting takes approximately between 6 and 24 months. Retrofitting existing vehicles also offers the following advantages:

  • Compared to continuous retrofitting through new procurement, the support for two systems is relatively short
  • Rapid availability of new functions such as video surveillance, passenger counting, dynamic passenger displays with live data – uniform for the entire fleet
  • Flexibility and expandability


  • Requires financial and human resources

But which way should you go for a transport operator?

Individual Decision Leads to Success

One thing in advance: Both paths have their justification. The decision on the right path must be derived from the individual situation of the transport operator. Important questions are:

  1. What time frame and requirements are there from the city administration/politics?
  2. How is the transport operator structured in terms of expertise and personnel?
  3. Which systems need to be digitized?
  4. What funding is available for this?
  5. How old are the vehicles on average?
  6. What is the planned rate of vehicle replacement in the coming years?

Our cooperation with more than 70 transport operators in the area of network infrastructure shows that there is no “universal concept” that fits everyone. Our practical experience shows that both small and large operations with fleets ranging in size from 10 to 1,000 vehicles are all able to plan and implement retrofits smoothly. The same applies to continuous retrofitting through the procurement of new vehicles. The important thing here is to involve all internal and external stakeholders in the project at an early stage.

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Our products are fundamental for the digitalization in public transport. ROQSTAR M12 Ethernet Switches provide the network infrastructure for e-ticketing, passenger counting systems (PCS), dynamic passenger information (DPI) and closed-circuit television (CCTV).


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