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Penny Tests for Transit

How to use a Penny Test to validate an Automated Fare Collection System

Launching an automated fare collection system involves many checks to ensure all parts are ready for public use. One of those important tests is a penny test. This whitepaper explains the penny test, its relevance to automated fare collection, how to conduct it, and how to design the tests.

What is a Penny Test

A penny test is used to validate that an automated fare collection system can correctly process transactions. It helps to confirm that every part of an automated fare collection system is working as expected. Penny tests typically involve processing small transactions through the system to confirm each part works as expected. These tests are essential for detecting errors in fare calculations, payment processing, and system integrity. By using small  transaction amounts, penny tests reveal issues that might not be obvious with larger amounts. 

How Robust Does the Penny Test Need To Be?

If your automated fare collection system is an integration of multiple systems (e.g. a systems integrator using multiple vendors), your penny tests should generally be more rigorous. On the other hand, if your automated fare collection system is more integrated, the penny tests might be simpler. TransitFare’s Automated Fare Collection system is one of these ‘all-in-one‘ type of systems.

Why a Penny Test Is Important

There are a few reasons why penny tests are important to do when launching an automated fare collection system. 

The goal of a penny test is to confirm that transactions move correctly through a system. Here are some examples of how transactions can move through an automated fare collection system:

  • When a customer purchases a fare, the fare is correctly ‘loaded’ to their account. This means the correct product, value, etc. 
  • The payment that the customer has made appears correctly in your merchant or bank account. 
  • The purchase transaction appears correctly in system reports (e.g. sales reports, reconciliation reports, etc). 
  • When the customer uses their fare product the transaction is recorded accurately (e.g. for fare validation). 

Also, transit fares tend to be smaller in value but high in volume. Small errors in processing these transit fares can result in major discrepancies, such as reconciliation reports being wrong. A penny test is a controlled way to verify that the whole system can correctly process fares and that financial reports are accurate.

To complicate things further, some automated fare collection systems are integrations of multiple independent systems. These might include a gateway processor, a clearinghouse, a third-party app, and possibly more. Doing a penny test is an important step to confirm that all of these separate systems are working together correctly.

How to do a Penny Test

Start with a Test Plan

Start by identifying different scenarios for payment transactions, including purchasing fares, refunds, discounts, etc. The complexity of your tests depends on the complexity of your automated fare collection system, your fare products, and all the ways that riders can purchase fares. 

Some fare collection systems, like TransitFare’s, are ‘all-in-one’. This means they are proven to work in the real-world and your tests can be simple. On the other hand, highly customized fare collection systems, or ones made up of several independent systems, require detailed tests.

Here are some sample test scenarios you might do:

  • Purchasing tests where you purchase one or more fare products. You might do controlled amounts like a single ride, or a single day pass. 
  • Doing fare validations on buses. For example, tapping for a single ride, and then a transfer.
  • Finally, doing a refund of any remaining fare balance remaining on your test cards.

Discuss your test plan with your automated fare collection system vendor to get their take on how to best complete your tests. 

Prepare the Test Environment

Preparing the test environment is a key step. The best way to do a penny test is in an environment that closely mimics the final system. This typically means that it is one of the final tests of the system before turning it on for public use. In some cases, you may be able to complete your tests in the actual final system. This might mean waiting until the system is fully configured, bus validators are installed, payment gateways are integrated, etc. 

Execute the Tests & Review the Results

Conduct all of your penny test scenarios by following your test plan. Record details about each test such as the date, time, bus number, and card ID. As you go through each test, confirm that the system is operating as you expect. This means verifying the accuracy of payment transactions, receipts, reports, etc. When you’ve completed the tests, confirm that the final reconciliation reports and card balances match with what you expect.

If you find errors, provide your automated fare collection system vendor details so that they can fix any issues. Once the issues are fixed, you’ll want to repeat some or all of the penny tests again.

Other Considerations

Remember that a penny test is typically a high-level test. It is mainly suitable for automated fare collection systems that are already well-tested or mature. If you are launching a highly customized or unproven automated fare collection system, you should include many other tests in your testing scope. Here are some other types of tests to consider in this case, with a brief overview:


The ability to handle a high volume of transactions is crucial. The automated fare collection system should be able to process lots of transaction quickly and stay accurate even under heavy  loads. This testing ensures that peak usage times, such as morning or afternoon rush hours, do not degrade performance or lead to errors.


Security is essential for an automated fare collection system. The system must be secure against potential threats and vulnerabilities, even when handling small transactions. Security tests can verify that the system securely processes transactions and protects sensitive data from unauthorized access or breaches.


Conducting a penny test is crucial for the successful launch of an automated fare collection system. By verifying the system’s ability to accurately process small transactions, you ensure reliability, accuracy, and user satisfaction. Design your tests with real-world conditions, and run them in an environment that is as close to the final system as possible. This approach will help you identify and fix issues early, ensuring a smooth system launch.

Selecting an ‘all-in-one’ system that is proven in the real-world, goes a long way to reducing the need to do detailed testing. If such a system is not an option, then going with a single integration vendor is the next best option. 

Talk to Us about Testing an Automated Fare Collection System