Drivers on I-405 are on the honor system when the power goes out.

When heavy winds in the Pacific Northwest knock out power to the express toll lane infrastructure, the Washington State Department of Transportation expects drivers to use the lanes as HOV-only, according to spokesperson Ethan Bergerson.

Related: Pockets of Western Washington could be without power for days

At least some of the I-405 toll signs went dark on Tuesday, putting drivers in the dark as to what is the proper usage of the lanes.

By treating the toll lanes as HOV-only, that forces people who would otherwise be paying for a faster commute, back into the general purpose lanes. Bergerson did not have an estimate for how much toll money was missed during the outage.

He said the Washington State Patrol continues to enforce the carpool requirements (three-plus) during an outage.

Drivers in the lanes were tolled at the rate of the next operational sign, according to WSDOT.

Though most of the signs had power restored by mid-morning, signs north of 128th were still out. That goes for thousands of Puget Sound Energy and Snohomish County PUD customers as well.

Bergerson said the toll signs have backup batteries designed for short term outages, lasting up to four hours. WSDOT did secure – overnight Tuesday – backup generators for future long-term outages.