The M5 was closed in both directions following the crash while inquiries were carried out and repairs were made to make the motorway safe.
National Highways confirmed at 10.20 GMT on Tuesday the northbound carriageway had reopened between junctions 24 and 25, and the southbound carriageway reopened shortly afterwards.
The site of the collision is near Creech Heathfield, close to Taunton.
There are long delays on local roads, especially the A38 near North Petherton and Bridgwater.
Motorists travelling southbound on the M5 have been experiencing delays of 90 minutes, with seven miles of congestion.
There have been delays of 30 minutes and congestion for two miles northbound.
Anyone who witnessed the collision or may have dashcam footage which could help the investigation is urged to contact police.