Even if RTC directors approve the project as expected, many issues will need further work. They include determining how many lanes will be on the bridge, what the structure will look like and, of course, how to pay for a project expected to cost $3.5 billion or more.

The Metro Council voted 5-2 Thursday to endorse building a replacement bridge with light rail. Councilors Carl Hosticka and Robert Liberty cast the two dissenting votes, as they did when Metro approved a June 5 resolution endorsing the project.

Danielle Cogan, spokeswoman for the Columbia River Crossing project, said so far none of the agencies has adopted a position that will stymie bridge planners from moving forward.

Many have attached a list of concerns or positions they want addressed as bridge planners move from the conceptual phase to specific design and engineering.

“I think it helps as a form of community guidance to say, ‘We think it is important. Incorporate it in your project,’ ” Cogan said.

Both Metro and the city of Portland support three through lanes in each direction, with the number of auxiliary lanes to be determined later.

Auxiliary lanes are used to provide an orderly flow for traffic entering and leaving at freeway interchanges and to reduce hazards as drivers jockey for position.

Crossing officials previously have said they believe they can reduce the number of auxiliary lanes from three to two in each direction and still maintain adequate traffic flow.

Another critical issue for Portland interests is climate change and greenhouse gases. The Portland City Council’s resolution calls for an independent analysis of greenhouse emissions and how much additional automobile travel could be created by building a larger bridge.

Portland also wants to see a bridge with a signature design, a position that could require crossing officials to push the Federal Aviation Administration to accept a design that intrudes on Pearson Field’s airspace, as the lift spans of the existing crossing have for more than 90 years.

But the biggest challenge remains securing money to pay for a colossal bridge, freeway and transit project.

Cost at issue

The project’s critics continue to characterize it as “a $4.2 billion bridge,” a misleading figure in a couple of ways.

First, a replacement bridge spanning the Columbia River is only a little more than a third of the overall cost. Freeway improvements and transit account for most of the cost. One example: Rebuilding the Marine Drive interchange in north Portland is expected to cost $750 million.

Second, the most expensive option, a replacement bridge with a light-rail line ending north of Kiggins Bowl, would cost an estimated $3.9 billion to $4.1 billion, but the crossing staff stopped studying that option three months ago.

Vancouver and C-Tran have selected Clark College as the ending point for light rail. The project’s draft environmental impact statement places the total cost for that project — bridge, freeway and transit improvements — at $3.4 billion to $3.6 billion.

That study envisions tolls as the project’s biggest funding source, used to pay off as much as $1.35 billion in construction debt. Portland supported variable tolling, where high rates are charged during rush hour, that would be collected “in perpetuity.”

Metro went one step further, calling for placing tolling on the existing twin spans “as soon as legally and practically permissible” and to consider adding tolls to the Interstate 205 bridge as well.

In contrast, Vancouver stripped all references to tolling from its bridge approval. C-Tran’s resolution also is silent on tolling.