July 26, 1999
WOODINVILLE--The heavy traffic congestion on 131st Ave. NE, between SR-522 and NE 175th, might soon improve, thanks to cameras that trigger the lights.
The cameras, loaned to the City on a free, six-month trial basis by Odetics of Anaheim, Calif., cover all four directions of the 131st NE and NE 175th intersection. The State of Washington contributed free installation of the cameras.
"The State had a great incentive in clearing the traffic exiting SR-522, especially since SR-202 (Woodinville-Redmond Rd., running north-south along the west side of the slough) begins at that intersection," said Mick Monken, Woodinville Director of Public Works. "We saw a big improvement during Monday evening's peak-hour traffic, but it was still pretty jammed up during yesterday's (last Wednesday's) rush hour."
Monken said the City has no current plans to install the cameras at other intersections between the freeway and NE 175th. The cameras have worked well in other parts of the country, he said. The main disadvantage to their automatic triggering of signals occurs during heavy fog conditions.
The City turned to the camera experiment because the heavy truck traffic in the area breaks the traffic signal wires (called "detection loops") buried in the asphalt in a matter of months. "Whenever you cut into the asphalt (to bury the detection loops), you compromise the integrity of the pavement," said Monken.
Heavy loads cause a "shoving" effect, especially on hot days when the pavement is softer. Trucks are longer and heavier than they used to be. Experts have estimated that a single, heavily-loaded semi has the same impact on pavement as 2,700 cars. Those heavy trucks move the pavement at the cuts in the road, breaking the wires.
"At 131st and 175th, we had 32 loops broken within six months after installing them; some of them were broken in much less time. Our recent repavement of that intersection involved removing the old surface, to get rid of the tread 'valleys' caused by heavy traffic. Vehicles tend to follow those valleys, which causes a constant pushing out effect on the asphalt. Without the detection loop grooves, the integrity of the asphalt is not hurt as much," said Monken.
Monken said the City also hopes to install cameras at the intersection of 140th Ave. NE and NE 175th. The City plans to replace pavement there due to damage caused by tree roots. Plans for installing detection loops there were interrupted by the Endangered Species Act (ESA), said Monken.
"A biological assessment found that our work might impact three endangered species of bats in the area," he said. "Bats generally feed on bugs in very moist areas and in old trees. We're hoping to find possible mitigation by creating more habitats for bats in our parks, so we can go ahead with our improvements at the intersection."
Monken said the City has not noticed any moist area or old trees near that intersection, but they are forced to abide by ESA rulings.