Millions of people who enter subway systems using fare cards never give a second thought to the technology underlying them. But the development of the world’s first commuter ticket–scanning machine that could check more than one rail pass per second was recently named an IEEE Milestone in Electrical Engineering and Computing.

The ticket scanner, which went into service in March 1967, was nominated by IEEE Life Fellow Isao Shirakawa, dean of the Graduate School of Applied Informatics at the University of Hyogo, in Kobe, Japan, and former chair of the IEEE Kansai Section, which sponsored the nomination. Shirakawa says that before the machine could be put to work at Osaka’s KitaSenri station, its developers first had to reinvent the way passengers accessed and exited the stations at the start and completion of their commutes.

Back in the 1960s, a commuter ticket used at Japan’s railway stations listed the holder’s name and age as well as the prescribed routes and the ticket’s expiration date. Gate agents had to read each ticket to verify that the rider was on the right route and the ticket had not expired. That task became nearly impossible as ever-increasing hordes of workers entered the stations during rush hour. In February 1964, Minoru Nakai, head of research at Kintetsu Corp., Japan’s largest private railroad company at the time, organized a group of researchers from his company, Osaka University, and Omron Corp. to create a machine to scan the tickets automatically.

Automatic ticket scanners were already in use, but they controlled so-called closed-gate machines; they opened a pair of doors after a passenger’s ticket was validated. Then, as the rider retrieved the ticket from the machine, the first doors closed and a second set simultaneously opened to let the passenger through. But those first scanners were real slowpokes. For example, one type at a tube station in London could process at most 20 tickets per minute. But to cope with the 60 000 or so passengers who exited Kintetsu’s AbenoBashi station in Osaka during the morning rush, a machine needed to process tickets three or four times as fast.

Nakai put two teams to work. One developed the logic architecture for checking a ticket’s validity—was it being submitted at the correct station, had it expired yet? The other team developed the hardware to control entry. Within a year, a 21-bit encoding scheme was developed that could deal with each of the 170 000 routes possible among the railroad’s 280 stations in the northern Kansai area, which includes Osaka, Kyoto, and Hyogo. And Omron built a machine that lowered a bar, instead of closing a door, to prevent entry if an invalid ticket, which was actually a plastic punch card, was inserted or if someone crossed a beam of light emitted by the gate without first inserting a ticket. During a one-month trial at AbenoBashi station with Kintetsu employees as test subjects, the system was fine-tuned to pass nearly 60 passengers per minute.

In March 1967, Hankyu Corp., a rival transit operator, took advantage of the advance by fielding a more refined version of Omron’s ticket reader, able to admit 70 passengers per minute, at its KitaSenri station. It was not quite the throughput desired, but good enough to do the job. Subsequent work by engineers from Omron and Kintetsu led to cards that carried information on thin magnetic strips, and machines to read them. They superseded the plastic cards, which were comparatively easy to counterfeit.

A ceremony commemorating the introduction of the ticket-scanning machine is scheduled for 27 November. Plaques noting the achievement are to be displayed at several significant locations: Omron’s headquarters, its R&D center, and the factory where the first prototype machine was built; at the respective headquarters of the train operators Kintetsu and Hankyu; and on the grounds of Osaka University’s Graduate School of Information Science and Technology. Plaques are also to be placed at the AbenoBashi station, which saw the first field test, and the KitaSenri station, where the machine made its public debut.

The aim of the IEEE Milestone Program is to highlight the roles in the advancement of science and technology played by the IEEE’s geographic regions and organizational units, such as its technical societies. The IEEE currently recognizes more than 75 engineering and computing milestones around the world. Innovative technical achievements that are more than 25 years old are eligible. For more information on the program, which is administered by the staff at the IEEE History Center in New Brunswick, N.J., visit http://www.ieee.org/web/aboutus/history_center/about/milestones.html.