height of above mean high water. The caissons, in turn, are submerged about beneath mean high water. At each end of the suspension span are two anchorages that hold the main cables, both of which are freestanding concrete structures measuring . The width of the bridge deck between the cables is . Unlike other suspension bridges, the Bronx–Whitestone Bridge originally did not have a stiffening truss system. Instead, I-beam girders gave the bridge an Art Deco streamlined appearance. After the 1940 collapse of the Tacoma Narrows Bridge, a bridge of similar design, trusses were added on the Bronx–Whitestone Bridge to minimize the span's oscillations. Further modifications to the bridge were made in 1988–1991 and in 2003–2005. Highway connections The Bronx–Whitestone Bridge carries Interstate 678 (I-678). In Queens, the Whitestone Expressway (I-678) extends south to an interchange with the Cross Island Parkway, located just past the end of the bridge's approach ramps. There is an exit from the bridge to the southbound Whitestone Expressway service road, and an entrance and exit from the northbound Whitestone Expressway to the northbound service road. In the Bronx, the bridge leads to the Hutchinson River Expressway (I-678). The expressway has exits and entrances in both directions to the Hutchinson River Expressway service roads, which in turn connect to Lafayette Avenue. The expressway continues north to the Bruckner Interchange, where I-678 ends and becomes the Hutchinson River Parkway; there are also connections to the Cross Bronx Expressway (I-95) and to Bruckner Expressway (I-278 and I-95). As most trucks carrying over have been prohibited from using the Throgs Neck Bridge (approximately east) since 2005, the Bronx–Whitestone Bridge is suggested as an alternative route for heavy trucks. Tractor-trailers exceeding and traveling between central Queens and the Bronx, as well as all heavy trucks over 53 feet that are banned from the Throgs Neck Bridge, are required to use the Bronx–Whitestone Bridge. History The idea for a fixed crossing between Ferry Point at Clason Point, Bronx, and Whitestone Point at Whitestone, Queens, was first proposed in 1905 by real estate speculators who wanted to develop Whitestone. At the time, residents around the proposed area of the bridge protested construction in fear of losing the then-rural character of the community. Plans for the bridge were submitted to the Whitestone Improvement Association in 1909, but they were not acted upon. Queens public administrator Alfred J. Kennedy later recalled that in 1911,