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Japanese inventor broke new ground with safety-conscious design 52 years ago today

BART and Muni’s tactile paving blocks helped make public transit more accessible

A stopped BART train with the tiled safety strip to its right.
Photo by Sundry Photography

Bay Area mass transit riders recognize the distinctive, bumpy grating on the yellow safety strip at BART and Muni platforms, but not everyone knows precisely from where it came. This tactile paving invention, known as “Tenji Blocks,” was first installed at traffic crossings in Japan 52 years this day.

Today’s Google Doodle marks the anniversary of this simple but critical “braille blocks” innovation. As Curbed notes, Japanese inventor Seiichi Miyake created the first such installation near a school for the blind in 1967.

The UK’s Department of Environment Transport Regions explains the distinctive surface’s utility:

When moving around the pedestrian environment, visually impaired people will actively seek and make use of tactile information underfoot, particularly detectable contrasts in surface texture.

[...] Tactile paving surfaces can be used to convey important information to visually impaired pedestrians about their environment, for example, hazard warning, directional guidance, or the presence of an amenity.

Research has determined that visually impaired people can reliably detect, distinguish and remember a limited number of different tactile paving surfaces and the distinct meanings assigned to them.

In San Francisco transit, there’s more to the layout of “blister pavement” than immediately meets the eye.

Take a look at the yellow line on a BART platform and most of the bumps turn out to be in an “offset pattern.” As Henshaws, a charity for the visually impaired, explains, this design is used specifically on train platforms “to warn visually impaired people of the edge.”

But on the black portion of the strip, denoting where the train doors open, the bubbles align into neat rows. This pattern tells riders who may not be able to see that this is a safe point to step forward; it’s the same pattern used at crosswalks.

Incidentally, this is one of the reasons why your BART conductor takes pains to line up the doors with the platform.

Note that Muni platforms don’t feature the black boarding sections of the platform strip. Muni trains tend to be a bit more haphazard with where they stop and open the doors.

However, regular light rail riders will also notice the “corduroy paving” on the train stairs—raised horizontal strips that run a different direction from those on the floors of the train.

“This type of surface warns visually impaired people of the presence of a specific hazard,” Henshaws explains—yet another variation on Miyake’s brilliant design.