Cable-Stayed Bridge

What It Means

A cable-stayed bridge is a long-span structure in which the deck is supported by an array of straight cables running directly from one or more towers (pylons) to the deck at evenly spaced anchor points. Unlike suspension bridges, which have a main cable from which hangers descend to the deck, cable-stayed bridges have cables attached directly between the tower and the deck, creating a more rigid overall system. Common cable arrangements include fan (all cables converge at the tower top), harp (cables parallel), and modified fan or semi-fan (the most common modern configuration). Cable-stayed bridges are economical for spans between roughly 500 and 3,000 feet, overlapping with the lower end of suspension bridge economy but offering faster construction, simpler anchorage, and lower cost because no massive gravity anchorages are required. U.S. examples include the Sunshine Skyway (Florida, 1987, rebuilt after the 1980 collapse), the Arthur Ravenel Jr. Bridge (South Carolina, 2005, main span 1,546 feet), and the Penobscot Narrows Bridge (Maine, 2006). Cable-stayed bridges came into widespread global use in the 1970s and 1980s and now represent the dominant long-span form for new construction in the 1,000-2,500 foot range. They are still a small minority of the NBI inventory, fewer than 100 structures, but include some of the most prominent bridges in the country. Inspection focuses on cable condition (stay cables typically use parallel wire strand or seven-wire prestressing strand bundles encased in HDPE pipe with grouting or air dehumidification), anchorage hardware, tower condition, and deck-cable interaction. Cable replacement is a specialized operation and a significant lifecycle cost item.

Frequently Asked Questions