If an Oregon-led version of the Columbia River Crossing project takes shape—something that may be dictated in the Oregon legislature next month—expect to pay $2.50 for the privilege of crossing the Columbia on I-5. If you're a commercial trucker with a five-axle rig, figure on $10.

And that's just if you have a special transponder.

This and many, many other figures met questions—and occasional cantankerous ire—today, as people hoping to build a new Interstate 5 bridge over the Columbia River made their case to Oregon lawmakers.

In a sometimes-testy, often dull hearing, a joint committee studying the bridge and highway project got its first detailed look at an Oregon-only version officials cooked up last year, when it became clear Washington legislators have no stomach for the CRC.

The new version scraps plans for jazzed up interchanges on the north side of the river, and places all liability for the project squarely on Oregon's shoulders. Lawmakers previously approved a version of the plan where Washington would take on half the liability for debt used to fund the bridge. That's no longer on the table.

CRC Project Director Kris Strickler and others made a detailed case the project is feasible, but big questions plainly remain. Planners are counting on $850 million in federal money that's not guaranteed, and agreements over tolling with Washington state have to be hammered out. And time is of the essence, backers say—both in terms of snagging federal money and locking in current interest rates on debt.

The hearing was more than four hours long and packed with minutiae. Here are some of the larger take-aways.

The current proposal is contingent on many things, but at the forefront is Oregon legislators conceding to pay for it. Strickler drew the ire of State Sen. Betsy Johnson early on by oversimplifying the situation, saying Oregon would still only be responsible for $450 million—the same amount as the previous iteration—for interchange improvements under the new plan. The state also would need to shoulder more than $1.3 billion in debt that would in theory be paid with toll revenue.

"For some of us that's one of the problems here—you've got to tease out answers," said Johnson, a Democrat from Scappoose and by far the most vocally skeptical lawmaker at today's hearing. "Before this hearing is over, I want to hear what the whole number is."

Construction on the new bridge could begin as soon as fall 2015, with tolling beginning on the existing bridge no later than January 2016. Tolling would occur between 5 am and 8 pm only, while the bridge is under construction.

Initial toll rates are assumed at $2.50 for passenger vehicles with a special transponder that debits money from a pre-paid account. Commercial trucks and other large vehicles would be charged more, based on the number of axles they have.

People without transponders would be billed based on photos of their license plates, and would have to pay more. Backers assume a portion of those users simply will not pay, but say they can still expect at least 86 percent of the toll money owed.

This didn't sit well with a lot of lawmakers, who wanted to know what authority Oregon has to enforce tolls on non-Oregonians—who will be by far the heaviest users. Assistant Attorney General Ethan Hasenstein explained the state has a variety of options—both criminal and administrative—for collecting revenue, but conceded deterring scofflaws would be paramount.

"Success of actually recovering revenues is limited at best sometimes," said State Sen. Jackie Winters, R-Salem. "I just don't want us to look at that as some kind of magic bullet."

"If there's no deterrent in the state of Washington from paying, I think that (86 percent recovery rate) is totally out of whack," said State Sen. Fred Girod, R-Stayton.

Upon completion of the bridge in 2021, rates would increase 15 percent and tolls would be applied 24 hours a day. Eugene Ryan, a staffer with CDM Smith, the firm that recently completed an "investment-grade" analysis on the project, told the committee those prices would be less than average tolls nationwide.

Ryan conceded to lawmakers the tolling would both reduce traffic over the river and push motorists over to I-205, which would still be free. According to the analysis, average traffic over the I-5 bridge would decrease from 125,000 per day to around 83,000. The Glen L. Jackson Memorial Bridge on I-205 would shoot up from 140,000 to 168,000 a day.

The committee spent a lot of time on this displacement, and lawmakers with districts along I-205 were not at all pleased with the specter of increased traffic.

And Johnson had this question: "How do we justify a bridge where the traffic is estimated to be less than what it is today?"

"Those vehicle crossings then build back up over time," Strickler responded. "The volume does come back."

The analysis hasn't taken into consideration how that would effect maintenance costs for I-205.

If it turns out the CDM Smith analysis is wrong—or if there are cost overruns for the project—lawmakers are free to hike the toll to meet debt payments. But that would further decrease the use of the bridge. CDM Smith says this works out, financially, and that it's confident in its calculations the bridge is a safe bet.

"We would expect the actuals to not be lower than we've estimated," Ryan said. "We believe those are very good estimates, and on the conservative side."

Not everyone was convinced. "What happens if you can't toll your way out of this problem?" asked Girod.

There was a good deal of skepticism at the hearing, but also lawmakers who seemed ready to embrace the Oregon-led CRC option. Among them was State Rep. Greg Smith, R-Heppner. Smith cheered the infrastructure improvements the CRC would offer at the problematic interchange at N Marine Drive and I-5, and admonished the committee that time is of the essence.

"If we're going to endorse this project, we better get moving," Smith said. "We have a lot of work to do, we have a lot of questions to ask, but the cost of delay should interest rates rise is significant for the State of Oregon."