TriMet is pitching a $1.7 billion bond measure to help pay for a new light-rail line as well as a slate of other regional transportation projects.

As currently imagined, the measure on the November 2018 ballot would impose a $13 vehicle registration fee and a new property tax assessment within the transit agency's service area. The tax assessment would cost the average homeowner an additional $150 a year.

The biggest single chunk of the money raised -- $740 million -- would provide part of the funding for the Southwest Corridor light-rail project, which would connect downtown Portland with Tigard and Bridgeport Village in Tualatin.

The remaining $950 million would be distributed to Washington, Multnomah and Clackamas counties, as well as the city of Portland, for congestion-relief and safety projects identified by those jurisdictions.

TriMet officials, who initially declined to discuss the matter, cautioned that the proposal is still in its early stages and that the numbers could change. Or it could decide not to pursue a funding measure at all.

"We're in this exploratory phase here," said Bernie Bottomly, TriMet's executive director of public affairs. "We know from the polling that we've done that the residents of the region are very concerned about congestion. They feel it every day, and they really want to see something done to address it."

A recent report from the Oregon Department of Transportation found that the hours of congestion in the Portland area grew by 13.6 percent from 2013 to 2015, a period during which the metro area's population grew just 3 percent. A booming economy, however, has put far more vehicles on the roads.

TriMet is currently in talks with the three counties and Portland to identify projects that would resonate with residents who might not directly benefit from the new light-rail line. The agency is particularly interested in congestion relief projects that could be completed within seven years.

TriMet had previously contemplated a measure that would pair transit projects with freeway expansions in all three Portland-area counties: Interstate 5 in Portland's Rose Quarter; Oregon 217 in Washington County; and Interstate 205 in Clackamas County.

But the Oregon Legislature undercut that possibility with its own transportation package, which partially funds each of those three projects.

The Southwest Corridor project didn't make the final cut in the transportation package because it would be too costly, said Sen. Lee Beyer, D-Springfield, who co-chaired a special committee that crafted the bill.

"Personally, I think that project makes a lot of sense," Beyer said. "But the people who are going to pay for that are the people living in the metro area. That's really an issue for them to decide."

With the "big three" freeway project off the table, TriMet set about reconstituting its plan. Those projects might still show up in an eventual ballot measure, however, if local funds are needed to supplement state and federal allocations.

The Southwest Corridor would also depend on a sizable federal contribution. It's expected to cost $2.4 to $2.8 billion in 2025 dollars, reflecting the time it would be under construction.

The outlook for federal transit construction funding is still unclear. President Donald Trump's budget proposal would cut the Federal Transit Administrations' capital improvement program, a version of which has funded nearly every MAX line (with the exception of the extension to Portland International Airport) and the Portland Streetcar's eastside expansion.

Congress, whose members value federal funding for projects in their home districts, might have different plans. The Federal Transit Administration continues to accept applications for funding.

Nonetheless, the ballot measure could be written in such a way that the light-rail portion of the package doesn't take effect until federal funding is secured, Bottomly said, which could give voters assurance that they won't be paying for a project that won't come to fruition -- or that it would hold back other projects.

Metro's Joint Policy Advisory Committee on Transportation, which includes representatives from various jurisdictions within regional government, will likely begin to vet the list of projects before the end of the year.

To get a measure on the November ballot, it would need approval from TriMet's Board of Directors in June, and the various governments involved would need to negotiate funding agreements in the meantime.

-- Elliot Njus

enjus@oregonian.com

503-294-5034

@enjus