WORLD’S FIRSTPLATFORM DOORSUSING
2DCODESINSTALLED AT TOEI SUBWAY STATIONS
2024 marks the 30th anniversary of the 2D code developed by the Japanese firm Denso Wave Inc. The Tokyo
Metropolitan Bureau of Transportation (Toei Transportation) has now collaborated with Denso Wave to develop theworld’s first 2D-code system for opening and closing platform doors at stations on the Toei Subway Asakusa Line inTokyo. The two are now offering the technology to other rail operators free of charge.
Platform doors installed atrailway stations prevent passengers
from falling on or entering thetracks. Transporting on average
about 2.2 million people a day on
all four of their Tokyo lines, Toei
Subway first introduced platform
doors on the Mita Line andquickly saw a sharp decrease in
the number of platform accidents.

Platform doors were subsequently
installed on other lines as well.
To operate the doors properly,
all train carriages require sensors
to allow synchronization of theopening and closing of the train
and platform doors. Installing
sensors across all trains, however,requires a significant amount ofmoney. On the Asakusa Line,

which is run by five different
railway operators, including Toei
Subway, the prohibitive cost ofinstallation caused difficulties
in reaching an agreement onimplementation of the doors.
To solve this problem,
OKAMOTO Seiji of theTokyo Metropolitan Bureau ofTransportation, who has worked

Left: OKAMOTO Seiji, a fellow in the Rolling Stock& Electricity Division of the Bureau of Transportation,
Tokyo Metropolitan Government, developed platform
doors that use 2D codes. He has been involved inplatform-door planning and design for more than 20years.
Right: The special 2D code, or “tQR code,” wasdeveloped by Toei Transportation and Denso WaveInc.

in railways for about
40 years, turned to thetwo-dimensional QR
code, a Denso Wave Inc.
registeredtrademark.
“2D codes hold up wellagainst dirt and can carrya lot of data. I thought
we could make gooduse of these codes, so I
approached the company
and asked if we could
work together,” recalls
Okamoto. Sensing thesocial impact of such amove, Denso Wave agreed
Left: A camera reads the data and movement of 2D codes attached to both train doors, signalling the opening andto the collaboration.
closing of the platform door.
What was developed Right: The camera seen in the upper right of the photo reads information from 2D codes, such as the number oftrain cars and the position of the doors.
after much trial and error
was the world’s first system that sunlight. “Even if up to half of the station platform is like walking
uses multiple cameras installed code cannot be read, it will not on a bridge without railings.
at the top of the station platform hinder the system’s operation,” In developing this system, wefocused on safety above all else.”
to capture the 2D codes applied asserts Okamoto.
The benefits brought about
Toei
Transportation
andto the glass of the train doors,
thereby automatically opening by the development of this Denso Wave share the samesystem are immeasurable. The passion inherent to Japaneseand closing the platform doors.
The 2D codes contain such cost of refurbishing the train manufacturing, namely a desire
information as the number of cars, originally estimated to be to deliver safe, quality products
train cars and total number of about 2 billion yen alone for the far and wide. Although the twodoors. The cameras read this trains managed by the Bureau of companies have obtained a joint
information and the movement Transportation was reduced to patent, they are providing thisof the codes. For example, by about 2.7 million yen. Not only technology without charging
reading the codes, the cameras have costs been reduced, but as a royalties. In response, othercan recognize whether the result of installing the platform railway operators are also using
train is moving or stationary, doors, the number of passenger this technology to install platform
and whether the train door is accidents at all Toei Subway doors.
“I’m sure the technology willopen or closed. The platform stations has also drasticallydoors can then be opened or decreased from 70 in fiscal 2011 be useful for railway operators
closed accordingly. Numerous to just two in fiscal 2022. With around the world, given thatexperiments were carried out platform-door construction on they may have been hesitating
during the development stage. the last station of the Asakusa about installing platform doors
These included adjusting the way Line completed in February 2024, for some reason or other,” says
the cameras and codes were set all 106 Toei Subway stations now Okamoto. No doubt both Toei
up so they could be read even in have them installed. Okamoto Transportation and Denso Wavean outdoor environment, such as says, “I’ve heard that for the will respond effectively to any
when wet with rain or reflecting visually impaired, walking on a interest from overseas.