$15 tolls for carpool lanes on I-405 and SR-167 start in March

Plus: Minimum tolls are going up to $1, and tolling hours will last an hour later on weekdays, through 8pm.

The big picture: Highway construction projects on SR-167 and I-405 face major funding shortfalls, which the increased toll rates will help address, the Washington State Department of Transportation wrote in an email to toll pass holders this week.

State of play: Right now, drivers pay a maximum toll of $9 on SR 167 and $10 on I-405 to enter the HOV lane if they don't meet carpool lane requirements.

• I-405 requires at least three people in a vehicle during peak hours to avoid a toll in the HOV lane, while SR-167's HOV toll lanes require at least two people.

What they're saying: Raising the maximum tolling rates to $15 is also designed to "discourage too many cars from entering the lanes," the transportation department wrote.

• That in turn will "improve travel time reliability," the agency said.
• Toll rates in the HOV lanes are based on the speed of traffic, with tolls lowest when traffic flows smoothly.