Distance-based tolls, peak-only tolling, and a wide range of rates from 50 cents to $3 are now on the table, as the Highway 99 tunnel’s toll advisory committee looks at a broader spectrum of ideas for raising revenue.

At a Wednesday meeting, committee members seemed far from solving the fundamental problem, after 11 meetings in 16 months.  Any toll high enough to reap $200 million for construction costs will cause drivers to opt for downtown streets, which are already near full. Models show there wouldn’t even be a boost in peak traffic on I-5 because the freeway is saturated.

Not only are tolls expected to finance $200 million of the $3.1 billion Alaskan Way Viaduct replacement over 30 years — but over the years, state officials quietly assumed the tolls could cover operations, maintenance, insurance and long-term equipment replacement, comprising another $400 million. Toll-backed financing is much weaker than what pro-tunnel officials assured the public back in 2009, when lawmakers voted to build a tunnel.

The latest scenarios include two that raise money:

• Varying the rates based on whether drivers enter and exit via local streets, or continue on the highway toward Green Lake, Shoreline, West Seattle, or Burien. This would be done using electronic readers at the South Lake Union and Sodo interchanges. In late afternoon, a “short” rate might be $1.20, a “medium” rate $2.10, or a “long” rate of $3.
• A simpler, high-revenue matrix of $2.25 morning peak, $1.50 mid-day, and $2.75 afternoon peak.

And two that minimize diversion to downtown streets:

• A peak-only toll of $1.75, charged from 6 a.m. to 9 a.m. and 3 p.m. to 6 p.m.
• Cheap rates of 50 cent off-peak, of 75 cents peak, and free at night.

In the latter two versions, the state misses the budget targets, and couldn’t use the tolls to back a bond sale.  And in all versions, at least 25 percent of what drivers pay would be spent just to cover costs of gathering the tolls.

The tunnel is scheduled to open to traffic in early 2016.

Projections say the high revenue version would cause the tunnel to lose 41 percent of vehicles compared to being toll-free — a debacle unless the vast majority switch to transit, carpools, telework or bicycles.

Toll diversion might clog bus routes throughout downtown, said Sung Yang, chief of staff to County Executive Dow Constantine. And Mark Bandy, state traffic engineer, pointed out that diversion would reach busy bicycling and pedestrian crossings, such as Boren Avenue at Olive Way, or Dexter Avenue North and Mercer Street.

“We don’t have any more scenarios — this is it. We’ve got to figure out how to get from this material to a recommendation,” said committee Chairwoman Maud Daudon, president of the Greater Seattle Chamber of Commerce and a longtime finance executive. Chances are, the group will combine these divergent ideas, she said later. Toll rates would need to undergo an investment-grade study, review by the state Transportation Commission, and passage by the state Legislature, under Initiative 1185.