After watching patiently as the freeway got widened and interchanges were improved north of town in Santa Rosa and Rohnert Park, Petalumans are about to get similar relief.

One Highway 101 interchange project is already underway and two more are slated to begin in late 2012 or early 2013, though it's unlikely that drivers will benefit from any finished projects until 2014.

Work on the East Washington Street Interchange started in December. Construction includes straightening a tightly curving southbound onramp on East Washington Street, adding a second lane on the interchange's northbound offramp, and introducing a new, northbound onramp that will eliminate the need for drivers headed west on East Washington to make a left turn to go north on the highway.

Right now, workers are moving utilities like phone and electric lines farther from the freeway, a process that will last into 2013.

Actual construction won't begin until the utilities have been moved, and the project likely won't be completed until late 2014, said John Maitland, the deputy director of planning for the Sonoma County Transportation Authority.

Two other projects will begin in late 2012 or early 2013.

The Petaluma River Bridge, which carries the highway across the river near Petaluma Boulevard South, doesn't meet today's standards and must be replaced. At the same time, a lane will be added to the bridge in each direction.

Also, Caltrans will turn the Petaluma Boulevard South interchange into a diamond shape, where four ramps lead to an over-crossing with traffic signals.

Vice Mayor Tiffany Ren? spoke with enthusiasm about the project.

"This is an important project that will put people back to work and ease congestion and inconveniences," she said. Ren? represents Petaluma on the board of directors of the SCTA.

She noted that the bridge and interchange have been combined to reduce construction cost and inconvenience to commuters.

Maitland believes construction on the project should begin in the fall.

Bridge work will require that southbound traffic be diverted at night for intermittent periods of time, for a total of about 40 nights.

To keep disruption at a minimum, only southbound 101 traffic will be diverted and then only during late night hours.

The project is expected to go out to bid this summer, and cost estimates are for $123 million from conception to completion.

A third project will replace the current interchange at Old Redwood Highway on the city's northern boundary. Work on that project is expected to begin in 2013.

Construction will impact traffic in 2013 and 2014, as all three projects get into full swing, according to Maitland.

Meanwhile, those hoping to see additional freeway lanes running through Petaluma will have to hold their breath a while longer.

Plans call for Caltrans to widen Highway 101 through Petaluma, adding an HOV lane in each direction. In the process, Caltrans is expected to elevate a portion of the freeway so that the much-anticipated Rainier Cross-Town Connector can one day pass underneath.

But there's currently no funding to construct the project, Maitland said. There is money available to design it, however, and the Authority is currently doing that work in order to have the project ready to go when funds become available.

"We're in the process of looking for other funds," he said. The SCTA is on the lookout for new federal or state grants that might become available.

According to a recent SCTA Highway 101 corridor update, about $86 million is needed to pay for the HOV lanes in Petaluma.

Most other projects to date have been funded through a combination of county Measure M sales tax funds and other city, state and federal monies.

Jay Gamel contributed reporting to this article.

(Contact Jamie Hansen at jamie.han sen@arguscourier.com)