Starting Monday, May 4 the Washington State Department of Transportation (WSDOT) will close the HOV express lanes on the Interstate 90 bridge across Lake Washington around the clock for up to three weeks.

This is likely to cause significant delays for all traffic – including buses and carpools.

Without the I-90 express lanes, WSDOT is warning that funneling all traffic into the mainline lanes across the bridge could result in delays of up to 40 minutes.

The state anticipates the delays will be most disruptive westbound in the mornings and eastbound in the afternoons.

And, there could also be related slowdowns on State Route 520, Interstate 405 and Interstate 5.

If you regularly use I-90 or SR-520 to cross the lake, it’s not too early to make plans for dealing with the projected congestion.

Metro is offering special vanpool and carpool incentives, and the bus is always an option.

As mentioned above, transit service will be subject to the same delays as other vehicles, but at least you help get one more car off the road and you can relax while someone else does the driving.

And don’t shelve your May plan, because there’s more work to come on the bridge in July when WSDOT closes down all the westbound mainline lanes.

Those delays are projected to be up to 60 minutes.