Acosta Bridge -- Traffic count average daily: 32,000

The Acosta Bridge spans the St. Johns River in Jacksonville, Florida on a fixed span. It was named for City Councilman St. Elmo W. Acosta, who convinced voters to approve a $950,000 bond issue for the original bridge. It carries SR 13 (six lanes) with the two-track JTA Skyway in the median. Prior to its replacement in 1991, the bridge, originally called St. Johns River Bridge, opened in 1921 and carried three lanes (center one reversible) on a lift bridge. Tolls were charged until 1940, earning more than $4 million for the City of Jacksonville. At some time in 1991, the original bridge was closed to allow construction of the new one to proceed.

Despite being a freeway, bicycles are permitted on the main lanes of the bridge.

The Acosta Bridge is also notable because of the blue neon lights that illuminate it at night.

The St. Johns River (officially Saint Johns River, but commonly spelled 'St. Johns River') is the longest river in the U.S. state of Florida, stretching 310 miles (500 km) from Indian River County to the Atlantic Ocean in Jacksonville in Duval County. The Saint Johns is north-flowing, which is somewhat unusual among U.S. rivers

The elevation change from headwaters to mouth is only about 30 feet, making the St. Johns one of the worlds "laziest" rivers. Extremely low velocity and low volume of flow, combined with the generally level elevation, cause the St. Johns to spread out to a great width for much of its course. During periods of low flow, the river can be influenced by tides as far south as Lake Monroe - 161 miles inland. For a distance of over twenty miles before arriving at downtown Jacksonville, the river's average width exceeds two miles and some points exceed three miles in width. The slow flow of the St. Johns makes it difficult for pollutants to be flushed from the waters, which has become a serious problem for the river ecosystem. It was designated as one of the American Heritage Rivers in 1997 and pegged by an environmental organization as the 6th Most Endangered River in America in 2008.http://www.ens-newswire.com/ens/apr2008/2008-04-17-01.asp Still, the river is home to numerous species of plants and animals. It is not uncommon to see dolphins in the river east of Jacksonville and manatees in the springtime when the water warms up. Alligators, bald eagles, ospreys, stingrays, and many species of fish?both salt and fresh water?are found living in the river and on its banks. The entire basin is managed by the St. Johns Water Management District.

Span is a section between two intermediate supports, e.g. of a beam or a bridge.

A span can be made of a solid beam or of a rope. The first kind of span is used for bridges, the second one used for power lines, overhead telecommunication lines, some type of antennas or for aerial tramways.

Category: Image - :Bending.png|frame|right|Side view of a simply supported beam (top) bending under an evenly distributed load q (bottom).

The span is a significant factor in finding the strength and size of a beam as it determines the maximum bending moment and deflection. The maximum bending moment and deflection in the pictured beam is found using:

:moment:   Mmax = 1/8 · q · L2

:deflection: fmax = 5/48 · Mmax· L2 / (E · I)

From this it follows that if the span is doubled, the maximum moment (and with it the stress) will increase four times, and deflection will increase sixteen times.

For remarkable long-distance rope spans, used as power line, antenna or for aerial tramways, see List of spans.