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Concrete sound barriers and train cars with hidden wheels to reduce noise are some of the possible mitigation measures for the Purple Line light rail that state officials plan to discuss with the Town of Chevy Chase, although town officials maintain their adamant stance against the project.

Town Mayor Kathy Strom said while the town hasn't conceded anything in its fight to keep light rail off the Capital Crescent Trail, which runs along the town's northern border, it plans to discuss what the Maryland Transit Administration will do to mitigate safety, noise, visual and other impacts within the next few months.

"They have indicated to me that they would like to discuss mitigation. To date, I haven't seen any specific plans," Strom said.

The Purple Line is a 16-mile mass transit project that would connect downtown Bethesda to New Carrollton in Prince George's County via Silver Spring. Gov. Martin O'Malley (D) chose light rail as the state's preferred alternative for the project on Aug. 4, with Federal Transit Administration set to study the project next.

Although light rail has the support of Montgomery and Prince George's county councils, the Town of Chevy Chase has advocated for a less expensive rapid bus system that would travel along Jones Bridge Road, rather than the trail.

The county's Planning Department staff wrote that without any mitigation by the MTA, the light rail could cause vibration impacts at or above acceptable limits defined by the Federal Transit Administration to homes within 40 feet.

"Site-specific mitigation techniques have yet to be identified," part of the January report reads, a fact which Madden confirmed on Friday but said ultimately will not be an issue.

"We will make sure there won't be vibration impacts," Madden said.

One key part of the MTA's general proposal to mitigate light rail's effect in the Chevy Chase area are concrete walls on both sides of the light rail from 2 to 6 feet high, intended to block out noise and vibration from the trains. The walls will be built around only the light rail, not the trail, and some of their total height could actually be obscured below ground, since in some cases the noise walls will double as retaining walls. The rail would be built below the trail in at least some sections, according to MTA renderings, obscuring the wheels of the trains from view.

The light rail train cars themselves will also have vehicle skirts, which are portions of the train that hang over the wheels. Vehicle skirts reduce wheel noise by up to eight decibels, according to the MTA. The state also said in its analysis that the noise impact of improperly maintained light rail wheels and tracks can be up to 20 decibels, 10 decibels less than a whisper in a quiet library. Even with proper maintenance the noise impact from the wheels is five to 10 decibels.

Lynda Williams, a resident of Edgevale Street, whose home abuts the trail, said removing the trees along the trail for light rail would damage more than just the appearance of the area, and couldn't be compensated for by sound walls alone.

"That's not going to be sufficient, because the trees are also going to be part of a sound buffer," Williams said.

Strom also said mitigating safety hazards of the trail is also one of the highest priorities for the town. In addition to the proximity of the rail to the trail, some residents have expressed concern about students crossing the trail going to and from Bethesda-Chevy Chase High School on East West Highway.

Currently there are two crossing above or below the light rail planned in the vicinity of the town. One would connect Lynn Drive to Montgomery Avenue, and another would connect East West Highway to Sleaford Road. Madden said the MTA would be willing to discuss other possible crossing areas.

"We have not yet dealt into the specifics of how we can make this the safest possible situation for our community," Strom said.