Southern Pacific Railroad's main north-south line through the San Joaquin Valley reopened after repairs to a track that cracked, causing 23 freight cars to derail near Goshen in Tulare County. At least five cars toppled onto California 99 early Monday, but the California Highway Patrol reported that no vehicles were hit on the highway, and no one was hurt. Railroad spokesman Gerald Pera blamed the accident on a transverse fissure of the rail that derailed the 19th through 42nd cars of the 58-car train bound for Portland, Ore., from Los Angeles. "Over a period of time, the molecular structure of steel broke down and caused a crack in the rail very similar to a pane of glass," Pera said. "At some point in time, something heavy enough comes over it to cause it to break apart." Damage was estimated at $100,000.