The George Washington Bridge's total width is . When the upper deck was built, it was only thick without any stiffening trusses on the sides, resulting in a deck weighing and a length-to-thickness ratio of about 350 to 1. At the time of the George Washington Bridge's opening, most long suspension spans had stiffening trusses on their sides, and spans generally had a length-to-thickness ratio of 60 to 1, which translated to a weight of and a thickness equivalent to an 11-story building. During the planning process, Ammann designed the deck around the "deflection theory", an as-yet-unconfirmed assumption that longer suspension decks did not need to be as stiff in proportion to its length, because the weight of the longer deck itself would provide a counterweight against the deck's movement. This had been tested by Leon Moisseiff in 1909 when he designed the Manhattan Bridge in 1909, though it was less than half the length of the George Washington Bridge. Stiffening trusses were ultimately excluded from the George Washington Bridge's design to save money; instead, a system of plate girders was installed on the underside of the upper deck. This provided the stiffening that was necessary for the bridge deck, and it was replicated on the lower deck during its construction. The plate-girders underneath each deck, combined with an open-truss design on the bridge's side that connected the decks with each other, resulted in an even stiffer span that was able to resist torsional forces.