If riding on Mitchell Road between Whitmore Avenue and the entrance to Walmart seems quieter now that a $881,470 street overlay has been done, it's not your imagination.
The reason why the street is quieter both inside and outside of a vehicle is due to the rubber that has gone into the asphalt mixture.
"It's a lot quieter both inside and outside," said City Engineer Toby Wells, "especially for high traffic areas with residences."
A $175,000 grant from Cal Recycle encouraged the city to go with the more expensive rubberized asphalt. Wells said that with the rubberized version costing about 17 percent more, or $88 per ton more than conventional asphalt, the city won't be using such materials in the future unless the costs come down or grant funds make up the difference.
Approximately 6,000 tons of asphalt went into the overlay of Mitchell Road from Whitmore to Walmart, which means the project's added costs are about $80,000 higher than they would be normally.
CalRecycle is offering the grants to help introduce cities and counties to rubberized asphalt to help create a market for repurposed rubber used from grounded up used tires. The idea is that the more contractors use the material the greater the costs will fall.
"It's more difficult for contractors to use it," said Wells. "They have to make a complete separate batch. So the more it's used ... it's supply and demand ... the costs will come down."
Besides less tire noise, rubberized asphalt has other benefits, he said. They include the environmental use of reusing recycled rubber, and giving the road better structural life.
"It's more elastic and it tends to last longer," said Wells. "It's estimated 25 percent more life."
Wells said that as a general rule of thumb, a typical street overlay lasts about 15 years but noted that Mitchell Road is well traveled with 40,000 cars per day which reduces asphalt life.
Less material has to be applied because it can be less in thickness.
The plan is to wrap up the Mitchell project soon.
The work is being done through a $881,470 contract with George Reed paving contractor. With a 10 percent contingency, the project could top out at $969,617.
Work also included replacing old concrete sidewalk corners along Mitchell with sloped and grooved sidewalk corners to make the sidewalks in conformance with the Americans with Disabilities Act (ADA) since it is a federally funded project.
The city is reconstructing Mitchell Road in phases due to the high cost. Last year the city performed an overlay of Mitchell from the Tuolumne River bridge to Hatch Road.
The third phase will involve an overlay south of Whitmore Avenue but federal funding may not be snagged in time for next summer, Wells said.