Detecting rumble strips, brick and grooves with a cane
Gallaudet University Campus, Washington, DC

The blind students at Gallaudet University have been having problems aligning and maintaining straight line of travel on some of the crosswalks on campus. At a meeting on accessibility, staff considered installing something to help address this problem, and wondered if the rumble strips that they use for traffic calming might be used for this purpose also. After the meeting, I went out to see if the rumble strips would work, and also experimented with their brick crosswalk.

These rumble strips could not be detected with the cane.

This brick feels the same as the concrete. It is a relatively smooth brick, but I've experienced several other crosswalks made with bricks that were more rounded which also could not be distinguished from the concrete of the road.

The groove at the edge of the crosswalk could sometimes be felt. However grooves can fill up with dirt and debris and become undetectable. Worse yet, cracks can sometimes be mistaken for the groove. For example, I once worked with a blind man who couldn’t keep straight when crossing the wide, wide driveway along Georgia Avenue, and there was a crack along the edge of the sidewalk that we decided he could follow the crack across.

It worked great, but one very scary day, the engineers had installed a wire into the pavement to actuate the signal, and left a crack that felt just like the one he followed across the driveway, but this crack went directly into the street. He accidently found that crack instead of the one going across the driveway, and followed it out into the busy, 6-lane street!

These rumble strips were distinctive from a car -- the bumps could be heard and felt. However they were not detectable with a cane.

Raised crosswalks might help provide alignment across the street. They might also slow the drivers, and slower drivers are more likely to yield. However, with raised crosswalks it's very important that the detectable warnings (truncated domes) are installed along the entire edge of the sidewalk that is level with the street, so that blind people can recognize when they are entering the street.

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