A panel of national experts told local leaders Thursday that a clear philosophy needs to emerge for tolling in the Interstate 405 corridor that balances the needs to finance a multi-billion project while also delivering the performance and congestion relief to make it worth the money.

In the second of a series of three meetings between national experts and local officials, the experts talked about the need to hash out some of the key questions related to who will be allowed to use the tolled, or high-occupancy toll (HOT) lanes for free, and how the project will be financed.

The nearly $2 billion plan to fund HOT lanes from Lynnwood to Bellevue didn’t make it off the Senate floor for a vote earlier this year, partially as a result of confusion as to how it would be financed.

The toll lanes are part of an overall vision to connect I-405 with State Route 167 and form an Eastside Corridor that flows seamlessly between Puyallup north to Lynnwood. The state has already installed toll lanes on SR-167 between Auburn and Renton. The state suggested using tolling as a means to pay for expansion of the Eastside Corridor, as funding from the gas tax runs low. But history shows tolling the roads won’t finance the entirety of the expansion, and the state Department of Transportation is tasked with finding state funding in a time when the budget has been cut repeatedly.

At the meeting Thursday, some leaders questioned what choice they had in the matter. The project won’t be a success if it’s not financed, so the money has to be the first priority.

“The assumption seems to be that you need this financing in order to build the project, that is the driving policy just by necessity to me,” said Bellevue City Council Member Claudia Balducci, speaking on behalf of Sound Transit. “It seems like this kind of policy discussion is almost meaningless. We can talk about it all we want, but when it goes down to Olympia they’re going to have to fund it.”

The other half of the question revolves around the effectiveness of toll lanes. Should they be free for carpools with two people, or must it be three or more? This issue has stirred up great debate in city councils and amongst communities. The national experts told leaders Thursday they need to be consistent in their policy. It shouldn’t be viewed as a city policy, but a regional decision.

“Large metro areas with traffic crises are looking at networks of traffic controls not just singular projects,” said Robert Poole, a transportation consultant. “For user experience the same rules would apply throughout the metro area.”

Complicating the matter further is that little history exists on such projects. Tolling on I-405 represents a “second generation” toll lane project, the experts said. First generation projects, such as the SR-167 HOT lanes focus on converting an HOV lane into a HOT lane. The I-405 project represents creating an entire transit system, linking together several different roads to ease movement throughout the congested region.

The congestion level could greatly influence the decisions local officials have to make. Several city’s in the area with HOV lanes for cars with two people are just as congested as general purpose lanes. The issue then becomes, if those lanes are converted to three-occupant vehicles, how much of the brunt will the other drivers take? Could switching the HOV lanes to three occupants per vehicle in only peak times be the solution?

“Three-plus in peak periods kicks out 75 percent of vehicles,” said Craig Stone, Washington Department of Transportation Toll Division director. “No one in this country has successfully made this transition toward doing that. The policy looks good, but it’s very hard to do.”

The expert panel is continuing to meet to discuss these questions. Another public meeting will be held on Nov. 10 in Kirkland, with the group’s final report due out in December.