The construction of the Petronas Towers turned out to be a multinational effort. The structural design engineers worked out of New York City, while the wind-tunnel consultants and elevator design engineers were from Canada. In order to meet local safety construction codes, the towers had to be able to withstand 65 miles per hour (105 km/h) winds. In order to assure this requirement would be fulfilled the engineers tested the towers twice within a wind tunnel, first by computer simulation and second by building an actual model of the towers.[22]