The current balsa wood bridge record holder from the 2013 Physics Balsa Bridge Building Contest was able to support 603 pounds, beating the previous record holder by 118 pounds. The balsa wood bridge holding the record is a tiered arch structure.
Prior to 2011, a balsa wood bridge capable of supporting 461 pounds held the record of strongest balsa wood bridge for 10 years.
Balsa wood is a very lightweight yet strong wood. It absorbs shock and vibration well and is easy to cut and shape using hand tools. It comes from the balsa tree, which grows in the rain forests of Central and South America.