“I don’t understand why there would be noise walls on one side of the freeway and not the other side,” said Travis Mosley.

Renee Mosley adds that in her opinion, the noise barrier built on the opposite side of Interstate 405 from their home on 21st Avenue Southeast has worsened the sound problem in their Bothell neighborhood.

She said the noise from the freeway bounces off the wall, heads up a sort of ravine and right smack into their home.

“It funnels right up the hill and right to our houses,” agreed neighbor Andrea Roberts.

At present, these families say construction along 405 only has exacerbated what they call a long-standing noise problem.

WSDOT (Washington State Department of Transportation) has almost completed an additional northbound lane on 405 between Northeast 195th Street and State Route 527. Deputy director of the 405 corridor project, Denise Cieri said the work on the 1.8-mile stretch of road should be finished by mid-June. With that completion, some noise complaints should abate, she said.

But Cieri also added there are no plans until at least 2012 for noise barriers on the south side of the freeway. And even then, her comments, as well as those of another WSDOT official, made the arrival of any new noise barriers contingent on a number of factors.

In information provided the Mosleys, WSDOT Public Information Office Sandy Lam said noise mitigation can take place when noise levels measured during a formal noise analysis reach 66 decibels. Though she did not say when the study was done, Lam added noise measurements taken in eight different locations around the Mosleys’ neighborhood read between 58 and 63 decibels.

For the Mosleys’ part, they contend those readings are simply inaccurate or that the measurements were taken in what they consider inappropriate locations. Travis Mosley said sound readings he’s been taking himself around his home measure anywhere from 69 to 74 decibels, even excluding noise from the current construction.

Mosley said a truck hitting an air brake or driving over one of the highway’s ripple strips create the upper-level rackets.

Cieri said tight state and federal regulations govern when noise barriers can be introduced. She said the barrier was added on the north side of the freeway because the new lane moved traffic closer to homes there. As for the south side, an upcoming transit project may trigger WSDOT to conduct a new noise analysis, which could potentially lead to southern noise barriers.

Basically, Cieri said WSDOT is looking for a way to move mass-transit vehicles through that stretch of highway more quickly. The solution could be an additional lane. Or buses may be allowed to use existing shoulders. In either case, traffic would move closer to homes and the noise-mitigation process might get a jump start. But again, Cieri gave no guarantees of walls appearing on southbound 405.

Cieri said the transit project itself is dependent on funding approvals. The study or design phase of the work could begin in July 2011 with construction starting in 2012. At that point, a WSDOT sound study still would have to show traffic noise had reached the 66 decibel level before any consideration of noise barriers.

As for the current construction, Roberts and the Mosleys said the work often shakes their homes. Roberts said her bedroom now includes a high-capacity air filter just to create some white noise to drown out the sounds of machines driving in guard-rail stakes. Cieri said the guardrail work often draws noise complaints. She said in this instance, it is being done at night to avoid having to close a lane of 405 during the day.

Cieri added noise is always the top public concern during construction projects.