A total collapse of the southbound Interstate 5 to northbound State Route 14 overpass occurred as a result of the February 9 , 1971 , Sylmar earthquake . This collapse resulted in the additional collapse of the intersecting southbound State Route 14 to southbound I-5 overpass ( as this connector bridge was directly beneath the 5/14 overpass ) . Both bridges fell directly onto the southbound I-5 truck bypass . There was damage to all structures involved , varying from minor cracking and splaying , to the loss of complete sections of bridges
Sylmar earthquake
1971 San Fernando earthquake
Newhall Pass interchange