MURRIETA -- Silence is golden, at least for engineers planning two new highway lanes through a city of 100,000 that booted its mayor over development issues not so long ago.

More than 20 employees of government agencies and their private-sector partners held a forum Thursday evening in Murrieta's City Council Chambers to explain their plans for expanding Interstate 215 to three lanes in each direction.

The residents dribbled through singly and in pairs, moseying from easel to easel, as the engineers and planners waited to discuss the colorful graphics and aerial photographs that were mounted there.

The plans call for a fifth and sixth lane on the southernmost seven miles of the highway between I-15 and Scott Road at Murrieta's northern border.

"It's sorely needed, I'd say as a resident and a developer," said Mike Morris, managing partner of Apex Development, which is building an office park a mile north of Clinton Keith Road along Antelope Road.

That was the sentiment of everyone at the forum Thursday night, and most drivers on the highway, no doubt. I-215 is the major route for tens of thousands of commuters who have moved out to Murrieta and Menifee in recent years, but at times in the morning and late afternoon, it looks less like a freeway than a 20-mile parking lot.

Environmental studies are already underway, and the Riverside County Transportation Commission, the coalition of county and city governments that is working on expanding the road, estimates that construction will be completed over the course of 2011-13. That may not be soon enough for the drivers who sit there five afternoons a week, but it's a relatively quick pace for a project that got its final piece of funding earlier this year, said Susan Vombaur, Murrieta's chief traffic engineer.

The transportation commission is receiving $38.6 million in state bond money for the lanes in Murrieta, one of several major road projects in the western half of the county to benefit from the $4.4 billion that California voters approved in November 2006.

Bill Hughes, whose company is doing the major engineering and design work, said public opposition has been virtually nil, a rare situation in California. Hughes remembers an effort to install noise-reducing walls along Highway 60 in Moreno Valley four years ago that pitted neighbor against neighbor, and all sides against his company and the road agencies.

The relative ease this time around comes from the fact that the new lanes are to be added in place of the existing grassy median. There are no testy homeowners to negotiate with, either about the price of their land or additional noise. Homes and businesses along the seven-mile section of the highway are already shielded relatively well from the noise of construction and the increased number of vehicles that could eventually result, Hughes said.

"It gets very challenging sometimes," Hughes said. "Particularly if the wall's not built on state property."

Joining Hughes on Thursday evening were several engineering colleagues, at least one representative of the California Department of Transportation, a couple of Murrieta city employees, coordinators from two public-relations firms and three staffers from the transportation commission.

Of the 20 or 30 residents who trickled through, most own homes or commercial property within a stone's throw of the highway. That's the kind of proximity, Hughes said, that draws out residents to protest many other highway projects.

Contact staff writer Chris Bagley at (951) 676-4315, Ext. 2615, or cbagley@californian.com.