The new laser-guided traffic signal at Gregson and Peabody streets doesn’t just tell you where to stop. If you’re driving a truck more than 11 feet 8 inches high, it also tells you where to go.
Clueless drivers on Gregson – often rookies in rented box trucks – have been crashing into a low railroad bridge there for decades. Their mishaps make for entertaining videos, thanks to the 24/7 vigilance of a webcam site called 11foot8.com.
Just watch the latest clip, Crash 107 (May 2), and you’ll know why they call this battered bridge The Can Opener.
A crowd of engineers and technicians spent Wednesday morning doing their best to spoil the fun.
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They switched on a sensor that emits a laser beam at just the right height above the Gregson Street pavement, near the Brightleaf Square entrance in the middle of the block. They used a long pole as a test to interrupt the beam – just as a too-tall truck would do.
That sent a signal to the new traffic signal 100 yards away at Peabody, turning the light from green to yellow to red. And it lit up a bright white LED message aimed at the too-tall-truck driver, who might get the hint while waiting for the light to turn green:
Is this perhaps too subtle? The subtext is: You still have time to avoid disaster by turning left or right on Peabody. Drivers will have 50 seconds – that’s how long the light stays red – to save themselves. Or not.
“The hope is that they will recognize that they triggered it,” said John Sandor, a state Department of Transportation traffic engineer overseeing the work. “And they’ll make that turn without hitting the bridge.”
The new installation on Gregson is paired with similar technology a few blocks away, at Roxboro and Pettigrew streets, that will go live later this month. The combined projects cost DOT $280,000.
The railroad bridge over Roxboro is even lower, 11 feet 4 inches. But it is not believed to snag trucks as often as the Can Opener does, possibly because it looks more forbidding: a low dark tunnel.
DOT tried for years to alert those hapless truck drivers on Gregson Street. An older laser sensor triggered flashing yellow lights on a striped “OVERHEIGHT” warning sign at Peabody. Still, the webcam captured a crash about every month.
Webmaster Jurgen Henn, a Duke University technology manager whose Brightleaf office overlooks the fabled bridge, posts the videos and contributes cheerful commentary:
There’s still human error. Until that factor is removed, the chance (of a crash) will always be there.
John Sandor, DOT traffic engineer
“Just another Friday afternoon at the 11foot8 bridge: wrong turn onto the one-way street, truck crashing into the 11foot8 bridge plus gridlock and general mayhem,” Henn wrote under an April 29 headline, “Dazed and confused.”
Acknowledging that the fun may not last forever, he added: “Soon the new traffic lights will put an end to all these shenanigans. Enjoy!” Henn could not be reached this week for comment.
DOT engineers said Wednesday the new signal will warn some drivers away, at least. And it will slow down the rest.
Instead of barreling down Gregson at 25 miles per hour or faster, the remaining Can Opener victims will be starting from zero at the Peabody stop light. It’s about 50 feet from the battered steel “headache bar” that protects the bridge and absorbs all those blows.
“The worst-case scenario is they’re a lot slower, so the impact will be marginal compared to what it was,” Sandor said. “There’s still human error. Until that factor is removed, the chance (of a crash) will always be there.”