This is a good question but semi trucks are NOT allowed to park on the shoulder of the freeway (including on and off ramps). I too have noticed vehicles on the shoulder during the overnight hours when looking at DOT cameras on SR-167. It appears they are using the shoulder as a resting area, which DOT assures me isn't allowed. If any driver needs to pull over to sleep, then they should to leave the freeway and rest at a designated rest area or truck stop.

I hope this helps to answer your question.

Cheers,
Jenni Hogan

Below is the official response from WSDOT:

Rick Roberts, WSDOT King Area Traffic Engineer, says:

It is illegal for vehicles to park or stand on limited access highways, such SR 167, as well as highway on- and off-ramps, unless directed by law enforcement or WSDOT personnel. Vehicles parked on the shoulders of our roadways reduce access for emergency responders and increase the risk of collisions, particularly those that occur in the early morning hours and involve alcohol and driver fatigue. WSP and WSDOT are working together to add more "no parking" signs at specific locations on area roadways, and WSP has been issuing citations for illegal parking in King County.