The Arkansas Highway and Transportation Department has requested permission for the placement of dredged and fill material in waters associated with replacing the Broadway Bridge and approaches crossing the Arkansas River in Little Rock and North Little Rock.
According to a notice published by the AHTD, the project would be done as part of a project to replace the Broadway Bridge.
“Construction would be on existing alignment with the existing bridge to be demolished before construction of the new bridge,” according to the notice.
The bridge over the navigable portion of the Arkansas River would require authorization from the U.S. Coast Guard (USCG) in accordance with Section 9 of the Rivers and Harbors Act. The existing bridge is supported by four piers in the river and has 331.3 feet of horizontal clearance for commercial navigation vessels. The new bridge would be supported by three piers in the river and would have 396 feet of horizontal clearance for commercial navigation vessels.
The existing and proposed bridges have 62.4 feet of vertical clearance (at navigation pool elevation 231.0 feet mean sea level) for commercial navigation vessels.
The public notice published by the USCG can be found at: http://www.navcen.uscg.gov
“The AHTD’s stated purpose is to ensure that the Broadway Bridge will continue to safely provide for modern transportation needs across the Arkansas River. The bridge is considered structurally deficient due to the condition of the deck, superstructure and substructure, and is considered functionally obsolete due to its existing roadway and deficient access ramps, according to the notice.
The existing bridge was completed in 1923. It totals 2,355 feet in length and its main spans consist of five open spandrel arch deck spans with 37 reinforced concrete tee-beam approach spans. In 1974, two concrete arch spans were replaced with a single steel arch span to accommodate the McClellan-Kerr Arkansas River Navigation System. The bridge has four 10-foot-wide lanes and two eight-foot-wide sidewalks; total width including railings is 60 feet.
Current traffic volume on the bridge is approximately 24,000 vehicles per day. Traffic is forecasted to increase to 35,000 vehicles per day by 2035. The AHTD plans to remove the existing bridge with explosives and excavators. The majority of existing steel would be removed and the concrete substructure would be dropped into the Arkansas River by use of explosives.
Approximately 12,000 cubic yards of concrete would be deposited into the river and approximately 8,000 cubic yards of that concrete would be recovered with excavators or clam shell buckets. The proposal to utilize explosives was made in order to reduce the time that the navigation channel would be closed and reduce overall demolition/construction time.
The new bridge would be a plate girder design consisting of two 448-foot basket-handle, network, tied arches that span the Arkansas River. The total length of the bridge, including approaches, would be 2,373 feet. It would have a concrete deck supported by steel substructure, and the roadway would consist of four 11-foot-wide travel lanes, and a 16-foot-wide shared use path on the eastern side. The shared use path would be protected from motor vehicle traffic by a concrete barrier.
Construction of the new bridge is expected to take a minimum of 18 months. Two temporary pile-supported work platforms would be constructed; one would be located on the south bank and west side of the bridge, the other would be located on the north bank and east side of the bridge. The primary effect from bridge construction would be disruption of motor vehicle traffic operations during construction. The bridge would permanently impact 0.14 acres of the Little Rock Julius Breckling Riverfront Park and 0.43 acres of the North Little Rock Riverfront Park.
The AHTD and the cities of Little Rock and North Little Rock have agreed to mitigation measures for the impacts to these parks. A special provision would be made part of the contract to minimize harm to migratory birds, such as swallow and phoebes, that periodically utilize the bridge for nesting. Impacts to the floodplain would be minimal and would not significantly increase flood heights.
The AHTD would coordinate with the USCG and Little Rock District Corps of Engineers to insure that there would be only minor impacts to commercial navigation on the river during demolition and construction. There are no wetland impacts and impacts to water quality should occur only during demolition and should be temporary; therefore, no mitigation would be required.
An existing gas transmission line on the bridge would be relocated. An existing water line, telephone lines and other communication lines would be placed on the new structure or an adjacent bridge. No federal threatened or endangered species would be impacted. No businesses or residences would be relocated, and there would be no impacts to historic properties. The Environmental Assessment (EA) evaluated five alternatives, including the no action alternative. The EA was completed by the AHTD on Aug. 7, 2012, and the Federal Highway Administration issued the Finding of No Significant Impact on Sept. 5, 2013