Sometimes it put Gamble, a traffic engineer with Clark County Public Works, on overtime.

That’s not needed with new gadgets that he calls “pole-mounted black boxes,” being used in Hazel Dell for the first time.

If you’ve driven on Northeast 117th Street between Second and Third avenues, you’ve seen these two 3-by-5-feet boxes, which cost about $10,000 each.

For a couple of weeks last month, after neighbors complained, the boxes silently collected radar data about how fast people were driving in the 30-mph zone, Gamble said in a bulletin.

Then, on July 2, Gamble turned on the large display screens that drivers headed east or west see.

It’s not too exciting if you’re doing 30 mph or less; you just see a black screen.

But if you’re exceeding the speed limit, the device shows some attitude.

Speeding drivers “trigger a bright, electronic display flashing a standard black-and-white speed limit sign,” he said.

So will the boxes convince flashed-at drivers to obey the speed limit, which is the idea behind them?

Or will drivers slow down for awhile, marveling at the new stuff, and then go back to lead-footing?

“The radar data will tell the ultimate story,” said Gamble, who plans to leave the signs where they are for more than a year.

Gamble said the boxes don’t have cameras and can’t identify individual vehicles. They don’t generate speeding tickets.

Gamble also uses smaller, more portable black boxes that he can place along a street and collect radar speed data, with no need for him to hang around.

Although neighbors frequently complain about speeders, convincing motorists to obey speed limits isn’t easy, officials say.

Within Vancouver’s city limits, officials mainly use trailer-mounted radar units that show drivers how fast they’re going, said traffic engineer John Manix.

“They tend to be very effective while they are in place,” he said.

And for a couple of years, the city has maintained a solar-powered radar speed-display sign, meant to operate 24/7, by Marshall Elementary School, 6400 MacArthur Blvd. It wasn’t working when a reporter drove by about 1:30 a.m. Thursday.

“It did not meet my expectations,” Manix said.

JOHN BRANTON covers public safety and law enforcement for The Columbian. He can be reached at 360-735-4513 or john.branton@columbian.com.