The truck driver told KRMG news the hydraulics on his truck malfunctioned, causing the bed to raise as he was driving.
The truck bed then rammed into the 169 overpass and came off in the left lane of the expressway.
The bed remains in the left lane of 44 under 169 causing the left and center lanes of the highway to be closed for now.
The truck was spreading salt and sand at the time of the accident and did spill contents that are now being cleared away.
ODOT workers told KRMG news the bridge was not severely damaged and there shouldn't be any issue with traffic on 169.
Check back at KRMG and KRMG.com as workers continue to clear the road.