Backups at the eastbound entrance of the Mt. Baker Tunnel and space constraints on the floating span would be problematic if future High Occupancy Tolls were added to I-90.
The latest review of one of the five proposed tolling schemes for I-90 to help fund a new floating SR-520 took place on Mercer Island, Friday, Dec. 12. The three-member 520 Tolling Committee held a formal hearing as they were presented with a WSDOT analysis of what traffic would look like and how much it would cost drivers to cross I-90 with High Occupancy Toll lanes, or HOT lanes, beginning in 2016.
During the presentation, it was noted that the width of the floating span carried challenges to implementing HOT lanes — as did the traffic jams from cars funneling into the Mt. Baker tunnel from I-5 and the Rainier Avenue South on-ramps.
One of the WSDOT presenters said there would be more congestion heading east into the tunnel under the proposed configuration, and necessary improvements would require rebuilding the I-5 and I-90 interchanges to get people into the correct lanes sooner.
Space constraints on the floating bridges were also a problem because HOT lanes require a two-foot gap between general purpose lanes. Sight issues on the bridges and drainage were other concerns found in the analysis.
The extra costs for the work to alleviate these issues were not evaluated, and Committee members said that those details would be needed to move forward with the proposal.
“That needs more work if it’s going to work out for us,” said Committee member and state Transportation Secretary Paula Hammond. “I’m taking it somewhat pessimistic. Westbound, I see some viability, but eastbound there are some challenges.”
The proposed toll scenario, dubbed scenario 10, is one of six other proposals that include tolls on I-90 and 520. The scheme looks at converting two of four general purpose lanes in both directions of I-90 into HOT lanes.
Currently, I-90 has six lanes total when not including the reversible lanes, but the state and Sound Transit are required by government agreement to add a fourth lane to the highway between Seattle and Bellevue in both directions prior to adding light rail to the center roadway.
The tolls analyzed by the WSDOT ranged from $.10 to $.95 per mile, depending on level of congestion. The stretch of highway between I-5 and I-405 looking to be tolled in the scenario is seven miles.
According to the breakdown of the price fluctuations, the morning rush hour costs for a single occupancy vehicle using the westbound HOT lane would be between $.30 and $.50 cents per mile and only $.10 per mile eastbound.
During the evening rush, the HOT lane would cost $.30 a mile in both directions or as low as $.10 per mile heading west. Those traveling east would pay $.70 per mile at set times.
The HOT lanes would generate about $254 million more after deducting the installation costs of the necessary infrastructure. Tolling the existing 520 bridge beginning in 2010 would generate $1.52 billion, and adding HOT lanes on I-90 would put a total of $1.77 billion toward the new northern span.
“I believe in the HOT lane system. You can envision a system [conversion] throughout the area,” said Hammond. “I don’t want to discontinue this idea. It’s a great idea for managing traffic if it works.”
