VANCOUVER -- The mayors of Portland and Vancouver have agreed on details of the Interstate-5 bridge across the Columbia River.

Wednesday afternoon, the Portland City Council also voted to approve the latest bridge plan; a compromise aimed at supporting the environment, funding and funneling traffic.

In a joint Op Ed story published in the Vancouver Columbian and in The Oregonian, Portland Mayor Sam Adams and Vancouver Mayor Royce Pollard wrote: “We must build a new bridge,” and laid out their join support for the so-called "jumbo plan". The compromise between the mayors calls for up to 12 lanes and a toll for crossing.

"It would be just three lanes once you get by the bridge, not six lanes pouring into Portland like some people seem to think," Mayor Pollard told KGW.

The number of vehicle lanes has been a hotly contested issue throughout the planning of the new bridge. In their opionion column, the two mayors lay out their argument for three through-lanes each way, and up to three “add/drop” lanes that the mayors equated to a thermostat that could be used to regulate the flow of traffic.

The mayors also made clear that some of those lanes would be dedicated to alternate transportation modes including HOV lanes and van pools.

"It would actually offer relief from congestion and pollution," Royce said.

According to the mayors, a final decision on the number of lanes was set for March. The Portland City Council was scheduled to hold public hearings on the Columbia Crossing bridge plan Wednesday at 3 p.m.

More: Read Mayors' Op Ed piece

Also: Experts: Bridge won't spur sprawl