After their final meeting on the matter, the Interstate 405 Executive Advisory Group is recommending an option that would keep I405’s planned HOT lanes open for two-person carpools during off-peak hours, but would switch to three-plus during busy times.

The group’s recommendations will help determine the future of the 40-mile long express toll lane system, encompassing I-405 express toll lanes and state Route 167 HOT lanes.

An HOT lane is a multiple-occupancy lane that is open to single-car drivers for a price, like the lanes on SR167.

The Washington State Department of Transportation has plans to install at least one of the lanes on I-405, but the state law states that HOT lanes must be designed to maintain a minimum speed of 45 mph 90 percent of the time and that tolls must pay for their operation.

Because of that, discussions over how to deal with the lanes have gotten complicated, with several advisory members, including Renton representative and City Council President Randy Corman, worried that the public will simply not accept a plan that changes the rules for HOT lanes to three-plus from the current two-plus option.

But WSDOT officials have concluded that a two-plus option is not viable because too many people would use the lane, making the speed requirement nearly impossible to meet, as well as not generate enough revenue.

According to Renton Public Works Administrator Gregg Zimmerman, the Nov. 7 meeting was “amiable,” and despite reaching a consensus, Zimmerman said all involved had an understanding that “not everyone is going to agree on every detail.”

In a presentation before the City Council on Nov. 4, Zimmerman detailed some of the city’s concerns, including that Renton city streets get a lot of use from people looking to avoid traffic on the highway, or that the I-405/state Route 167 connector project be funded at the front end of the phase two project to ensure traffic can continue to flow when the new lanes are added to the existing highway.

During the meeting, Corman also said he was concerned that a mandatory transponder would be necessary to use the HOT lanes, stopping the possibility of a spontaneous carpool from using the lanes.

Combined with what he sees as a potential loss to the public who are used to carpool lanes being two-plus, he said he had some concerns.

“It seemed like with a lot of the proposals, the incentive for carpool fades away,” he said.

In the end, Zimmerman said the advisory group went for a hybrid option, making the lanes three-plus during peak usage hours, but keeping them two-plus at other times.

Zimmerman also said funding recommendations were discussed. As of now, the state legislature has not passed a transportation funding package for this project and others.

Zimmerman said there were three options for funding being discussed. At the top level was a $1.1 billion package that would fully fund the entire 40-mile system without tools being needed to supplement the funding. In that case, tolls that are collected could be put to future improvements.

The next level of funding is a more traditional $960 million package that would require $215 million in tolling to complete the project.

Finally, the group discussed a $675 million option that would need $500 million to be collected from tolls.

Zimmerman said there was little support for the bottom option.

“It seemed to be pretty much between the high and the middle funding options,” he said of the discussions, adding that no consensus was reached on funding options.

The next step in the process is for the Washington State Transportation Commission to begin the rate-setting process, including tolls and exemptions, a meeting that will take place Nov. 20 in Kirkland.

After that, WSDOT will deliver a final report on funding and phasing to the legislature and governor by the end of the year.

The new lanes are expected to be opened by 2015.