Complex sentence: It was built to supplement the overcrowded Bridge of the Americas, and to replace it as the carrier of the Pan-American Highway; upon its opening in 2004, it became only the second permanent crossing of the canal.
Split into simpler sentences: It was built to supplement the overcrowded Bridge of the Americas and to replace it as the carrier of the Pan-American Highway. Upon its opening in 2004, it became the second permanent crossing of the canal.