 Complete the following phrase:  On December 1, 1951, a windstorm revealed swaying and rolling instabilities of the bridge, resulting in its closure. In 1953 and 1954, the bridge was retrofitted with lateral and diagonal bracing that connected the lower chords of the two side trusses. This bracing stiffened the bridge deck in torsion so that it would better resist the types of twisting that had destroyed the 