OLYMPIA — The Senate on Monday approved a $15 billion transportation revenue package that includes an incremental gas tax increase of 11.7 cents over the next three years.

The chamber passed the revenue bill on a 27-22 bipartisan vote and negotiations with the House will begin. They also passed a spending bill that designates the money to specific projects.

“Even though there are issues with it that we might all have, this is a process,” said Sen. Steve Hobbs, D-Lake Stevens. “In the end, I think we will have something that is very good for the state of Washington.”

Under the 16-year plan, the gas tax would increase in three stages: a 5-cent increase would take effect this summer, a 4.2-cent increase would follow next year, and then a final 2.5-cent increase would take effect the following year.

Sen. Brian Dansel, a Republican from Republic, said that nearly 12 cents a gallon may not seem like a lot, but “it adds up quite a bit for folks who have to drive greater distances to fill their rigs up more often.”

The Senate proposal includes more than $8 billion for road projects that include the North-South Freeway in Spokane and I-90 on Snoqualmie Pass, and puts money toward transit and local rail projects, as well as bike paths and pedestrian walkways. It also would allow Sound Transit to ask voters to fund potential expansions of its rail line.

The package also contains $570 million for projects in Snohomish County, including money for a new bridge on Highway 9 over the Snohomish River, and new freeway interchanges — on I-5 at the south end of Marysville, and on Highway 526 near the Boeing Co. in southwest Everett.

There’s also money for reconstructing the interchange of I-5 and 116th Street NE in Marysville; safety projects on Highway 2 between Snohomish and Skykomish; and relocation of the ferry terminal in Mukilteo.

One provision allows Community Transit, at some future date, to seek voter approval of a sales-tax increase to pay for additional service.

Snohomish County’s delegation split its vote.

Hobbs, Sen. Marko Liias, D-Lynnwood and Sen. Barbara Bailey, R-Oak Harbor, voted for it, while Sen. Kirk Pearson, R-Monroe, and three Democratic senators — John McCoy of Everett, Rosemary McAuliffe of Bothell and Maralyn Chase of Shoreline — opposed the package.

Bailey said inclusion of money to build another 144-car state ferry will keep many on Whidbey and Camano islands employed. But approval of eight reforms helped her decide, she said.

Pearson didn’t specify a reason for voting against the bill. He noted he’s not a fan of hiking the gas tax, and there are not many projects funded in his district.

“It’s not over yet,” he said. “This is a work in progress.”

The plan does not incorporate elements of Gov. Jay Inslee’s climate-based proposal, which would have charged polluters under a cap-and-trade program to pay for transportation projects.

Part of the plan also addresses another idea Inslee is considering, a low carbon fuel standard that would require cleaner fuels over time. If that standard is ultimately adopted, under the Senate plan, all non-bondable revenues — such as fee-based money going toward transit and bike paths — would instead be moved into the main transportation account, a tie that several Democrats decried, even some who ultimately voted for the bill.

“I really would strongly prefer to be able to vote on the revenue and the projects and not have that other policy debate brought into this bill,” said Sen. Jamie Pedersen, a Democrat from Seattle who voted in favor of the package.

Last Friday, the Senate passed eight bills tied to the package, ranging from environmental permitting to adding “congestion relief and improved freight mobility” to existing state goals.