OV-chipkaart: 30 million transactions per week


The OV-chipkaart (Public Transport Chip Card) is the national electronic payment system for all public transport in the Netherlands. It is a complex system with multiple participants, each of which purchase their own equipment from various independent suppliers. In order to ensure smooth operations, effective organisation is necessary. This is provided by Trans Link Systems (TLS).

Article from Objective 16, 2011

The OV-chipkaart was gradually introduced in the Netherlands in 2005. The card can now be used in public transport throughout the country. We are therefore the first country in the world with a single electronic payment system for all types of public transport. And while the card is simple to use, the underlying system is extremely complex. The OV-chipkaart system is a decentralised system. Every transport company has their own sales equipment, inspection equipment and check-in/out points or gates. These are then connected to a central computer within the company. These computers are then connected to Trans Link Systems' central system.

Trans Link Systems was set up in 2001 by five major public-transport companies in order to set up and maintain the OV-chipkaart system in the Netherlands. The organisation is at the top of the OV-chipkaart pyramid. It processes all transactions conducted in the Netherlands and divides up the money collected (clearing & settlement). This currently adds up to nearly 30 million transactions per week, a number that continues to rise. TLS also controls card distribution. Finally, TLS determines rules to maintain and improve manageability of the system. To use the language of the trade, TLS is the scheme provider. "This term originates from the financial world", explains Bram Schot, Scheme Manager for TLS. "A scheme is a set of rules and agreements about how parties interact with each other and how equipment is supposed to function. For example, there are PIN schemes and credit-card schemes."

Open architecture

The OV-chipkaart scheme involves a wide variety of equipment produced by many different suppliers. For this reason, TLS has set up a strict list of specifications, known as the System Documentation for Open Architecture (SDOA). "This contains a description of the functionality of equipment", explains Schot. "Which interfaces there are and what conducts (use cases) are possible. All equipment must comply with the SDOA."

TLS monitors compliance of the scheme via certification, amongst other methods. "Once a supplier has achieved this certification, access to our architecture specifications (SDOA) is granted. They then develop the equipment based on these specifications", explains Scheme Expert Peter Schonewille. "The supplier then submits this equipment for certification, as we need to ensure that it complies with our specifications. The tests for this certification are conducted for us by Technolution. Officially, we are the certification body, although we have outsourced all of the tests to Technolution."

Technolution tests all equipment that is used in the scheme, i.e. all of the equipment that consumers will encounter. "Technolution has developed everything about the testing process themselves, including the tools. Furthermore, they have built up a great deal of knowledge that can also be applied in other areas", says Schot.

Continually in development

Although the OV-chipkaart is fully in operation, developments have not ceased. New functionalities are still being added using existing and new equipment. "The number of physical sales points is falling as sale via the internet is increasing. As a result, new machines are necessary in stores – as well as buses – where internet orders can be picked up. A recent development is the use of the OV-chipkaart in the Regiotaxi minibus service, for which new machines are also currently in development. The scheme is continually on the go; it is a never-ending process", says Schot.

Use cases

Within the OV-chipkaart scheme, every participant has a degree of autonomy. Everybody has the opportunity to devise something new, often in conjunction with the suppliers. TLS is involved in this process in order to test that everything fits within the framework of the scheme. "We like to be involved at as early a stage as possible", emphasises Schot, "this enables us to contribute to the thought process." Every new machine or every software/hardware adjustment must be certified before it is implemented. The supplier indicates which use cases are supported by the equipment. "A use case is an exact description of a function, and what the machine must do in that particular situation", explains Schonewille. For example, if you chose an automatic-recharge card, the equipment will ensure that an amount is automatically loaded onto the OV-chipkaart if the balance drops below a particular level. "And that is what we test: whether the machine complies with the use cases and interfaces, or whether it performs the correct steps. Technolution then compiles the results in a report and records any problems encountered during the tests. We assess this report and assign a rating of satisfactory, minor problem, medium problem or major problem. The report is then shown to the supplier, who can then solve any problems that may have cropped up. If no problems need to be addressed, then a certificate is awarded for the machine."

Test kit

To give suppliers a helping hand, Technolution developed a set of testing tools. This allows suppliers to test the product for themselves before submitting it to TLS. "The test kit has helped increase quality enormously", says Schonewille. "Previously, a rejected product would have to be sent back to the supplier, who would make changes and resubmit it for testing. This process would often have to be conducted twice or three times. That is inefficient and costly. The test kit enables suppliers to make many changes before they submit the machine for certification."


Schot: "Technolution's most important service to us is certification. However, they also have a great deal of knowledge and can answer any questions we may have. We have a close relationship that dates back a long time. They helped us in the creation of the system documentation, and thanks to their tests, which allow us to continually improve the specifications, they continue to help us optimise it in a specific and measurable manner.

"It is important to cardholders that the OV-chipkaart works at all times", summarises Schot. "That's the difficult part: we have to keep it simple. The card must be compatible with all of the different types of machine. The situation that one particular machine registers (check-in/check-out) must correspond to the situation at the previous machine. You do not see this process, but it is essential that it works correctly. This is what makes it so complex. The easier it seems from the outside, the more difficult it is on the inside. This is what makes these certification tests so important: they guarantee this certainty so that we can build upon it.

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