The accident happened around 6:00 a.m. Tuesday on westbound Route 422 near Township Line Road.
Police say 40-year-old Brendon Landon of King of Prussia was traveling behind a vehicle driven by 26-year-old Rigoberto Paralta-Lopez in the right lane gong westbound.
Lopez's vehicle had a malfunction and stopped in the traveling lane.
Landon couldn't stop and rear ended Lopez's vehicle. Landon's car overturned and came to rest in the left lane.
Lopez's vehicle went down an embankment and hit some trees.
Both were taken to area hospital with moderate injuries.
Officials temporarily closed the westbound lanes of Route 422 and the ramps to Township Line Road while crews work to clear the scene. Traffic was also backed up for miles in the eastbound direction approaching the accident scene.