OLYMPIA – Gov. Jay Inslee has signed a new two-year transportation budget to keep state troopers on patrol, state ferries operating and help solve the problem of traffic back-ups on the Edmonds waterfront.

But he emphasized Thursday that the state still needs lawmakers to approve a 16-year proposal to raise billions of additional dollars for building new roads and bridges and expanding bus service statewide.

House and Senate negotiators are meeting regularly to reach agreement on the much-discussed plan that would generate around $15 billion in new spending, with a big chunk coming from an 11.7 cent-per-gallon hike in the gas tax.

The Senate version would spend $570 million on projects in Snohomish County. The House plan earmarks around $330 million in the county.

“Passing a transportation package is the single best thing the Legislature can do for Washington’s economy,” Inslee said in prepared remarks. “I remain optimistic that with collaboration on both sides of the aisle and serious purpose, we can get these critical investments across the finish line this year.”

What Inslee did sign authorizes spending $7.6 billion on road projects already under way and for the day-to-day operations of Washington State Patrol, Washington State Ferries and the departments of licensing and transportation.

This budget, which relies on collection of the existing gas tax and fees such as vehicle registration, also provides $500,000 for a study on ways to reduce back-ups of traffic bound for the Edmonds waterfront caused by frequent trains traveling through town.

It also pledges money to Island Transit to restart service from Camano Island to Stanwood and downtown Everett on the condition the agency makes those riders pay a fare. Island Transit does not currently charge fares for any of its bus service.

And the spending plan sets the stage for another increase in ferry fares to help keep the cash-strapped marine transportation system afloat. On Tuesday,the Washington State Transportation Commission is to consider the potential amount of the hike to put before the public for comment. An increase could take effect as early as October.

On Thursday, at about the time Inslee signed the transportation operation budget, House and Senate negotiators from both political parties wrapped up another round of talks on the long-term package. Participants said they are slowly paring down their disagreements over how to spend the money and what reforms to pursue.

“I feel there is a really strong possibility that we’ll get to an agreement,” said Sen. Marko Liias, D-Mukilteo.

Sen. Steve Hobbs, D-Lake Stevens, the ranking Democrat on the Senate Transportation Committee, said the gap between the two chambers is narrowing.

“We’re making progress,” he said. “I think once the operating budget is passed, we will rapidly close the differences.”

One disagreement is a provision in the Senate-backed proposal that would redirect money for public transit to roads if Inslee pursues a new low-carbon-fuel standard.

Republican senators oppose the standard and contend it will hurt consumers by increasing the cost of gas.

Another point of contention is use of the sales tax revenue collected on road projects. Those dollars now go into the state general fund to pay for government operation. House Democrats want to keep it that way, while Senate Republicans are pressing to retain those dollars for transportation improvements.

And the two chambers differ on a request from Sound Transit, which could limit its ability to bring light rail to Everett. Sound Transit is seeking permission to raise up to $15 billion from new or higher taxes, with voter approval. House Democrats are supportive, but Senate Republicans want to cap the tax-raising authority at $11 billion.

Jerry Cornfield: 360-352-8623; jcornfield@heraldnet.com.