Magnetic-stripe

Magnetic-stripe tickets are cardboard or plastic tickets with one or more stripe of oxidized material that can be encoded to hold data. The data on the stripe can be read and written to by authorized machines for a variety of purposes including fare collection and ticket inspection.

The ‘magnetic stripe’ is not strictly speaking magnetic. It consists of an oxide material which can be configured by magnets (a read/write head) so that it holds information in the form of bits. This is the same principle as tape recorders. The data includes information such as ticket issuer, ticket type or fare product, time period or dates of validity, limits of use (modes, zones, number of trips, peak-off-peak) and transfer permissions. The stripe may also include information about the most recent use (e.g. date, time, operator, route, boarding point)

In the urban passenger transport industry, magnetic stripe tickets use two formats:

Credit-card sized, which is the industry norm. This almost always has a single magnetic stripe on the ‘rear’ of the ticket. In most cases the stripe is centrally located, so that the card can be inserted in either direction, but some older configurations had the magnetic stripe offset. The relatively large ticket area on the ‘front’ of the ticket is used either for graphics and information, or as a printable area.
‘Edmonton’ type tickets, which are considerably smaller, and were best known as the tickets used on the Paris Metro.

Magnetic-stripe tickets were the main advanced form of ticketing in the 1970s and 1980s, but since then they have been gradually displaced by smart-cards. Some systems, such as London, still operate smart-card and magnetic-stripe tickets in parallel.

Magnetic-stripe tickets are used to assist automation of the fare collection and ticket inspection processes. They are designed to be read by a machine, which then initiates a process. The main applications are:

Passes: The machine verifies that the ticket is valid for travel. This relates to time-based passes (day, week, month, etc.), employee passes and concessionary passes. Normally, the machine will emit a distinct sound corresponding to acceptance or rejection of the ticket’s validity, for the benefit of both the passenger and the driver / conductor.
Journey-based tickets: Decrementing the number of trips remaining. This relates to single-journey and multi-journey tickets. In the case of a single-journey ticket, the ticket cannot be reused (except for permitted transfer). For multi-journey tickets, the number of trips remaining is reduced by one on each validation, until eventually no trips remain. Information about the trip is normally printed on the ticket.
Stored value: An amount of travel value is stored on the card. The machine calculates the applicable fare and deducts it from the stored amount, creating a new balance. The remaining balance is usually displayed on a screen and printed to the ticket.
Transfers: Some fare products permit transfers within a specified time. The machine checks whether the conditions for transfer apply, and either accepts the ticket as valid for travel without further deduction, or deems that a new trip has commenced and deducts another trip or value.

Some magnetic-stripe tickets are ‘read only’, meaning that the ticket-issuing machine just reads the content of the stripe but does not then alter the content. In most cases, the ticket-issuing machine will adjust the data content of the stripe. Even where there is no deduction to be made, the data about the most recent validation will still be added.

Benefits of magnetic-stripe tickets are:

The tickets are machine-readable. This allows automation of fare collection and inspection processes.
Fares can be calculated and deducted automatically. Authorization for transfer can be verified automatically.
A wide range of fare products can be offered using the same ticket medium. The information on the ticket can be set to suit the fare product, issue context, use context, etc.
Transaction data can be generated, with extensive downstream potential.
The technology is used widely. It is supported by international standards.
A reasonable level of security can be achieved, requiring potential fraudsters to have more advanced technology available to them.
The consumables are relatively inexpensive.
The tickets can accept graphics for promotions and information.
The ticket stock has no value (other than the consumable cost) until the ticket is actually issued.

Cautions with regard to magnetic-stripe tickets are:

Machines for issuing tickets need to be purchased and maintained.
The machines have many moving parts and complex electronics. This requires technical capacity of the operator, and has more risk of failures.
Supply and control of ticket stock needs to be managed and monitored.
Although reasonably secure, the technology required to replicate them is readily available, and fraudulent production on a large scale is possible.