Ticket validation machines are an important part of public transportation systems. They are used to validate tickets, passes, and cards, ensuring that riders have paid the correct fare to access the system. Validation machines use a variety of technologies to read, scan, and verify tickets. Here is an overview of how ticket validation machines function.
Ticket Insertion
Most validation machines have a slot or feeder that allows riders to insert paper tickets, passes, or cards. This slot will have a sensor that detects when a ticket has been inserted. The sensor triggers the machine to pull the ticket inside and position it for reading by an internal scanner or reader head.
Sensors
There are a few common types of sensors used in ticket validators:
- Optical – A light beam shines across the slot opening, detecting when it is interrupted by a ticket.
- Mechanical – A lever arm is tripped when a ticket pushes through.
- Electronic – An electric circuit detects the ticket’s presence.
The sensor alerts the validation machine’s internal mechanisms to grab and move the ticket into reading position.
Ticket Transport
Once the sensor is triggered, the ticket is gripped and pulled further into the machine by a series of rubberized drive rollers. These rollers feed the ticket along the transport path and alignment tracks, ensuring it is oriented correctly for scanning.
Scanning Position
The transport rollers move the ticket under the reader head or optical scanning elements. The positioning tracks bring the ticket into the proper focal range for scanning. Most systems use either a magnetic read head or an optical scanner at this stage.
Ticket Scanning
The validation process involves scanning the ticket to read data encoded on it. This data provides details like ticket type, expiration, and other parameters needed to verify validity.
Magnetic Stripe Reading
Many paper tickets have a magnetic stripe along one edge. This stripe contains encoded data about the ticket’s characteristics. A read head contacts the magnetic stripe to read the data as the ticket passes by.
Barcode Scanning
An increasing number of modern tickets use barcode encoding rather than magnetic stripes. Optical scanners shine a red laser beam across the ticket surface to read these barcodes. The barcode contains the ticket data in an encoded format.
OCR Reading
Some tickets have printed validation codes that must be read optically. Optical character recognition (OCR) technology is used to convert these numeric codes into digital data that can be checked against databases.
RFID Scanning
Contactless smart cards and tickets with embedded RFID (radio frequency identification) chips are also common. The validation machine uses an RFID reader to pull data from the card or ticket wirelessly using radio signals.
Ticket Verification
Once the ticket data has been read, the validation machine must verify that the ticket is valid for the requested access. This involves cross-checking several ticket details against parameter databases.
Ticket Type
The system must check that the ticket is the correct type for the mode of transit. Single ride, roundtrip, monthly pass, etc. are all different ticket types that provide varying access to the system.
Expiration Date
The date coding on the ticket data is compared against the current date to see if the ticket has expired. This prevents use of outdated tickets.
Origin and Destination
For systems with fare zones, the origin and destination stations encoded on the ticket are checked to calculate the required fare. This verifies that the proper ticket type was purchased for the route.
Blacklisting
The encoded ticket data may also be checked against a blacklist database. This helps identify known invalid or fraudulent tickets to prevent unauthorized access.
Fare Calculation
If the system requires fare calculation based on travel zones or other factors, the validation machines will handle this processing. Fare data tables stored in the system provide the needed pricing parameters.
Zone Fare Structure
For transit systems with tiered pricing by zone, the required fare is looked up based on the origin and destination stations encoded on the ticket. This ensures that proper fare was paid for the intended trip route.
Time or Distance Based
Other pricing structures may involve calculating fares based on trip duration or distance traveled. In these cases, data like boarding time, current time, or distance between stops is used to determine the expected fare.
Stored Fares
If the ticket or card contains stored cash value or prepaid fares, the validation can simply deduct the price of the current trip from the stored balance. This is common with prepaid contactless cards.
User Interface
Validation machines provide a user interface that allows interaction with transit riders. This includes displays, buttons, and other components.
Display Screen
A digital display screen provides information and prompts to direct riders through the validation process. This screen typically shows messages including:
- Insert ticket
- Processing…
- Authorized – Thank you
- Invalid ticket
- See attendant
Interactive Buttons
Buttons allow riders to interact with the machine. Common buttons include:
- Start/enter – begin processing
- Language – select screen text language
- Help/info – view assistance
Audio Guidance
For accessibility, validation machines may also provide audio guidance and prompts coordinated with the display screen information. Riders can follow audio directions to progress through the validation process.
Ticket Return
Following validation, the machine must return the ticket to the rider. The mechanisms involved depend on the ticket type.
Magnetic Stripe Tickets
Magnetic stripe paper tickets are returned to the rider through a slot just below the entry feeder. The drive rollers reverse direction to propel the ticket out of the return slot.
Disposable RFID
Disposable contactless smart tickets may not need to be returned. In some cases these are simply ejected into a disposal bin within the machine following validation.
Retainable Cards
Plastic contactless smart cards are reusable and should be returned to riders after validation. In this case they are fed back through a separate return slot by the drive roller system.
Data Connections
In addition to processing tickets, validation machines also communicate data about each transaction. This facilitates collecting ridership data and connecting to the central transit system.
Wired Networking
Historically validation machines used wired ethernet connections to transmit data back to the central system. This allows collection of audit logs and ridership statistics from each validation transaction.
Wireless Networking
With the growth of cellular data networks, many modern validators use wireless data radios to connect back to the central system. Wireless networking allows more flexible machine placement.
Data Transmission
The validators transmit back validation logs and fare transaction data. This facilitates real-time monitoring of system access as well as compilation of long-term ridership statistics and travel patterns.
Maintenance and Serviceability
Like any complex electromechanical system, validation machines require regular maintenance and service to remain functional. They are designed for maintainability.
Modular Design
Validation machines commonly use modular subassemblies for major components. This allows replacement of individual scanner, display, or printer modules without needing to replace the entire machine.
Access Panels
Easy access panels on the validator exterior allow technicians to freely access internal modules without fully disassembling the unit. Common slide out modules include:
- Ticket scanner
- Display screen
- Receipt printer
- Sensors
- Control boards
Onboard Diagnostics
Machine control boards include onboard diagnostics to monitor operation of subsystems like sensors, scanners, and motors. Diagnostic modes can be activated locally or remotely to pinpoint faulty modules.
Remote Updates
Validation machine software and firmware can be remotely updated via their data connections. This allows bug fixes and performance enhancements without needing to access each individual machine.
Security Features
Maintaining security is also a key consideration in validation machine design and operation.
Tamper Monitoring
Sensors monitor the physical integrity of the validator housings to detect tampering or forced entry. Alarms trigger if the enclosure is breached.
Encrypted Data
Sensitive ticket data is encrypted during storage and transmission to prevent interception or manipulation of fares.
Blacklist Database
As noted above, the validator frequently checks ticket data against blacklists of known compromised or invalid tickets to maintain access control integrity.
Emerging Innovations
As with any technology there are always innovations emerging to further enhance validation machine capabilities and convenience.
Expanded Networking
New networking options allow validators to tie into expanded backend systems. Integration with smart city infrastructure is one example.
Mobile Integration
Validators are integrating with mobile platforms, allowing use of smartphones as tickets. This provides added convenience for riders.
Adaptive Processing
Sophisticated data processing algorithms allow validators to adaptively adjust sensitivity thresholds to optimize scanning marginal quality tickets.
Video Monitoring
Cameras and video analytics provide monitoring around validators to augment security.
Conclusion
Ticket validation machines play a critical role in mass transit access control andfare management. As ridership grows globally, enhancement of validation technology will continue to be an important priority. The trend is toward faster processing, expanded networking capability, and greater integration of emerging mobile platforms. With their complex integration of sensors, data processing, and electromechanical modules, validation machines exemplify how sophisticated automation technology can enhance infrastructure system operations and the user experience.