Because of thermal expansion of the steel cables, the height of the upper roadway is lower in summer than in winter. The Narrows is the only entry point for large cruise ships and container ships that dock in New York City. As a result, they must be built to accommodate the clearance under the bridge. At mean high water, that clearance is . The RMS "Queen Mary 2", one such vessel built to Verrazzano-Narrows Bridge specifications, was designed with a flatter funnel to pass under the bridge, and has of clearance under the bridge during high tide.