It's still a long road to achieving total traffic relief on the freeway in Petaluma, but significant work is now underway on three of four major projects meant to alleviate congestion.

"The flurry of (construction) activity is gratifying because we've been waiting for it," said County Supervisor David Rabbitt, who lives in Petaluma, "but it's also terrifying because of what's to come, the long wait time for these projects to be completed."

Indeed, local drivers can buckle up and expect years of construction in Petaluma, with one project expected to take until 2016 to complete and another not yet funded.

But while not many are excited about the coming traffic delays, almost everyone is pleased with the prospect of traffic relief on the often-congested stretch of highway.

"We're almost reaching the finish line in terms of freeway work," Rabbitt said.

An upgrade to the East Washington Street interchange that began in December of 2011 is expected to be completed later this year, according to officials with the Sonoma County Transportation Authority, which works with Caltrans on local highway improvement projects.

Construction on the East Washington Street interchange 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.

That project is moving forward ahead of schedule, according to SCTA spokesman James Cameron, despite some uncertainty over redevelopment funds that Petaluma had been counting on to help pay its share of the project.

Another large project with many components broke ground in early April. The $120 million undertaking combines several smaller projects into one in order to reduce construction cost and inconvenience to commuters. Those projects include widening and updating the Petaluma River Bridge to meet modern safety standards, widening the overpass that runs above Lakeville Highway, and rebuilding the Petaluma Boulevard South interchange into a more conventional diamond shape. Once finished, four on-ramps will lead to an over-crossing with traffic signals. The project will also include widening the highway and creating frontage roads between Lakeville Highway and the Petaluma Boulevard South interchange in preparation for the eventual addition of an HOV lane through town.

Demolition is currently taking place on the Lakeville Highway bridge in preparation for the widening of the bridge, work that has required detours in recent weeks. Detours are expected to continue through the late spring and early summer as the structure is actually widened.

According to Caltrans, the new Petaluma River Bridge will be constructed in three stages. They are anticipating a challenging project since it involves building over the Petaluma River. Caltrans is also constrained in when it can work on the bridge by environmental concerns such as nesting birds and endangered frogs and fish. The entire project isn't scheduled to be completed until 2016.

A third project also broke ground this spring to replace the current interchange at Old Redwood Highway on the city's northern boundary. Cameron said this upgrade will include a new, higher bridge, as some large vehicles have trouble clearing the current one. It will also feature two lanes in each direction instead of one. Work is expected to wrap up in 2015.

Meanwhile, those hoping to see additional freeway lanes running through Petaluma to match those to the north of town still have a longer wait in store.

Plans call for Caltrans to widen Highway 101 through Petaluma from Old Redwood Highway to Lakeville Street, 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.

All the current activity of updating interchanges and creating frontage roads is paving the way for the highway widening, but there's currently no funding for the $90 million project itself.

There is money available to design it, however, and the SCTA is currently doing that work in order to have the project ready to go when funds become available. Cameron added that the agency is actively seeking funds for the project.

Rabbitt, who sits on the SCTA board, said that finding local dollars will be key to obtaining additional state and federal monies. He pointed to an extension of Measure M as one way to provide those local dollars.

Measure M is the county-wide, quarter-cent sales tax that voters passed in 2004 to fund Highway 101 improvements throughout the county. The funds ran short before all the widening work in Petaluma could be completed.

(Contact Jamie Hansen at jamie.hansen@arguscourier.com.)