State highway engineers have one idea on how to limit the time traffic will be affected during construction of the new Broadway Bridge - blow the old one up.
Using explosive charges to demolish the old crossing between Little Rock and North Little Rock and allowing it to drop into the Arkansas River likely will require less time than dismantling it piece by piece, Arkansas Highway and Transportation Department officials said in interviews last week.
“I would suspect [the contractor is] going to want to blast it,” said Carl Fuselier, head of the department’s Bridge Design Division.
The new bridge is being built on the same site as the old one. Removing the old bridge as quickly as possible will shorten the project and thus the time the 24,000 motorists who use the bridge daily will have to take alternate routes.
The department has estimated the crossing will be unavailable for at least 18months, but agency officials have said they won’t know precisely how long until the contract is awarded, likely in July. The contract will include incentives to reduce the time the route is closed to traffic. The officials say that if the contract is awarded in July, the bridge likely will be closed to traffic by the end of the year.
Department contractors have taken down bridges before using explosive charges, but it isn’t that common, especially in populated areas. The last time explosive charges were used to take out a bridge was in 2005 when the U.S. 70 bridge over the White River at DeVall’s Bluff was removed, said Danny Straessle,a department spokesman.
Downtown explosions, technically called implosions, attract crowds. In February 1980, hundreds of people, including Gov. Bill Clinton and Little Rock Mayor Webb Hubbell, braved frigid temperatures to watch the demolition of the historic Marion and Manning hotels. Explosives were used to take down the two hotels to make way for the Excelsior Hotel, now the Marriott Hotel, and the Statehouse Convention Center.
At the same time, if the contractor decides to use explosives to remove the bridge, the contractor will be responsible for removing the resulting debris from the river to protect the environment and keep the navigation channel safe for barges and other river traffic, department officials said.
The contractor “just can’t let it fall in and leave it there,” Fuselier said.
He said barge traffic will be “alerted ahead of time” and the contractor will have a “short period of time” to clear the navigation channel.
The decision on how to remove the bridge is one of many considerations facing contractors as they decide whether to submit a bid for the project. Over the past couple of weeks, the department has been allowing contractors to review the 528 pages that hold the latest designs, specifications and notes for the new bridge. Agency officials caution that the design still has to be finalized, which is why they won’t allow copies to be made. But contractors can take notes.
The winning contractor isn’t required to dot every “i” or cross every “t” in the final design, not if it can figure out a way of doing the project, or parts of the project, that better serves the taxpayer and the commuter alike, highway officials said.
The design is “used to communicate with the contractors how we see the project being built,” said Chuck Martin, the department’s assistant division head for roadway design. “They may look at it and they may see different ways of doing things.”
The quantities of the materials required for the new bridge aren’t being provided yet. But department officials say they estimate the project will require 35 million pounds of reinforcing steel, 20 million pounds of structural steel and 17,000 cubic yards of concrete.
The department has said the existing bridge, which was opened to traffic in 1923, remains safe, but is becoming too costly to maintain. It notified local officials about three years ago that the bridge would be replaced. The department estimated it would cost $58 million to build what it deems a safe, efficient and functional bridge.
Pulaski County committed another $20 million to incorporate two basket-handle arches into the design instead of just one. That money would be paid over several years.
The raft of pages contractors have been reviewing for what the department has dryly designated Job No. 061227 contain detailed schematic drawings and notes on almost every aspect of the new bridge, including the roadway changes leading up to the bridge on both sides of the river, the construction and design specifications, the minimum strength requirements for the steel and concrete that will be used in its construction, and even specific designs for each of the new traffic signals.
The bridge design diverges sharply from a department policy that aims to streamline designs and specifications to improve communication, economy and speed in getting a project from design to construction.
“This is such a different type of bridge, all of it isn’t covered in our [standard] specifications,” said Trinity Smith, the head of the Highway Department’s Roadway Design Division.
The design includes a requirement that the concrete deck be 6 inches thick all the way across except for one lane that will be designed for possible future use for the River Rail system; that lane will use 16 inches of concrete.
The concrete pavement has a design life of 20 years with traffic projected to be 30,126 vehicles a day on the bridge by 2033. Twenty years is a typical life of pavement design, Smith said.
The bridge is expected to hold up far longer - 75 to 100 years, according to Fuselier.
From the overall design, it is evident that what will be the new Broadway Bridge is a collection of bridges, including the main bridge, a new bridge, or ramp, for southbound motorists to exit onto LaHarpe Boulevard, as well as bridges for pedestrian access on both sides of the river, including access to Dickey Stephens Park in North Little Rock.
“Everyone focuses on the one over the river, but there’s more to it than that,” Fuselier said.
Front Section, Pages 1 on 02/10/2014