Caltrans tests out grinding methods for reducing noise
Saratoga resident argues for asphalt replacement
Completion target: March
By Rebecca Ray
A Saratoga resident thinks he has found the best way to reduce traffic noise on Highway 85. But the California Department of Transportation and Santa Clara Valley Transportation Authority are testing another technique.
The Saratoga resident, Robert F. Karlak, who cofounded the Freeway Noise Abatement Committee, thinks that asphalt concrete pavement should be poured over the Portland concrete cement pavement on Highway 85. A study done by the Wisconsin Department of Transportation shows that asphalt is the more cost-effective than concrete, Karlak said.
But Caltrans and the VTA are experimenting with another way to make the road smoother: grinding down the ridges of the grooves. They are currently testing this method on a section of Highway 101 in Sonoma County, which has the same concrete pavement as Highway 85. If VTA officials find that grinding down the ridges on Highway 101 reduces traffic noise by at least three decibels--or cuts the amount of noise in half, then they will consider grinding down the ridges on Highway 85.
Saratoga and Cupertino residents who live along the "corridor" of Highway 85, a six-mile section of the freeway below ground level that passes between high walls, have complained about traffic noise since the highway opened in October 1994. The noise even bothers residents such as Saratoga resident K. K. Lin, who lives about four blocks, or some 750 feet, away from the freeway. The noise magnifies as it bounces from the road to the walls and out into more distant neighborhoods, said Cupertino resident Ardith West, co-chairwoman of the committee, who lives about 1 1/2 blocks away from the freeway.
"The noise is always there, and it's pretty loud," Lin said.
Sometimes, he has to pick the right time to go to Kevin Moran Park, which is next to the freeway.
"It really defeats the purpose of having a quiet park," he said.
According to Lin, the noise is even louder at night. He has to close all the windows in his house, even in the summer, to be able to sleep.
"It's really affecting the residents here, especially small children," Lin said, adding that the noise is damaging the rural nature that is characteristic of Saratoga.
Lin and other residents voiced their concerns at the most recent Saratoga City Council meeting, in the hope that council members will put more pressure on Caltrans and the VTA to reduce the noise. Members of the committee, which formed one month after the highway opened, have communicated with the Santa Clara County Board of Supervisors about the noise issue, and will meet Jan. 15 to enlist the support of local politicians, assembly members and state senators.
Karlak said he doesn't see why Caltrans and VTA officials are even studying grinding, and has produced and played them a video he says shows how concrete highways produce more traffic noise than asphalt highways, even when the ridges of the concrete have been ground down. Karlak, a retired research scientist, filmed sections of highways 85 and 17 and interstates 680 and 880 and measured traffic noise with a sound level meter in view of the camera. He found that Highway 85 produced more noise than the asphalt Highway 17 and Interstate 880, and found virtually no difference between Highway 85 and Interstate 680, where the ridges of the concrete have been ground down.
Although officials from Caltrans and the VTA haven't ruled out asphalt, they believe they must consider other factors. Asphalt requires higher maintenance than ground concrete and is a continuing maintenance problem, said Mike Evanhoe, VTA director of congestion management and highway programs. When asphalt wears, it can't absorb as much sound, and noise levels increase. Also, asphalt separates from concrete, which forms potholes.
When Caltrans commissioned noise-reduction consultant firm Acentech to study various methods, including asphalt, in 1996, Acentech found that asphalt would reduce the noise level by three to five decibels.
Caltrans and the VTA began to study grinding after July 1999, when the county board of supervisors approved $9 million for sound mitigation. Caltrans and the VTA are scheduled to complete the grounding study in March and should have the results by April, Evanhoe said. Then VTA and Saratoga and Cupertino city officials will recommend a method, before Caltrans, which owns Highway 85, decides which method to use.
Saratoga, California Since 1955
