Highway Projects

Route 85 Noise Mitigation Project Texture-Grinding Test Project

Overview:

The Santa Clara Valley Transportation Authority (VTA) Board of Directors authorized a texture-grinding (also known as micro-grinding) test project on a section of Route 85 to assess the potential to reduce tire noise along Route 85 between I-280 and Route 87 in Santa Clara County.

Project Description:

Texture-grinding is a newer type of pavement grinding in which machines with parallel saw-wheels grind away roadway surface bumps and rough spots, leaving a smooth surface with a pattern of narrow, longitudinal grooves while retaining safe skid resistance. The concrete pavement industry asserts that texture-ground pavement is quieter that traditional diamond-ground pavement.

The test project section was located just north of the Prospect Road area and extended southerly for less than a mile. Grinding operations lasted approximately two weeks. Crews monitored noise levels in the freeway right-of-way and on surface streets both before and after the grinding operations.

The trail study indications that texture-grinding the freeway pavement reduced overall noise but it was less than the 3 dBA threshold that is perceptible to the human ear. However, the study determined the grinding caused a downward shift in the tonal characteristics of the sound and decibel reductions at frequencies that are easily heard by human ears. Based on comments from the community, the combined effect has been a perceived reduction in noise.

Project Schedule:

Texture-grinding test project

Started: July 2002

Completed: September 2002