Many things change over the course of 70 years, especially traffic patterns, which has certainly been the case for the Homestead Grays Bridge over the Monongahela River in Pittsburgh.
The bridge is currently undergoing a reconstruction with a completion date of Nov. 23, 2007 — 70 years after it originally opened in 1937.
The contract for the project was awarded to Balfour Beatty Construction, under the direction of Ed Barrickman, for a total of $35.2 million. Funds are 85 percent federal, with the Pennsylvania Department of Transportation (PennDOT) contributing an additional 10 percent and Allegheny County, PA, contributing 5 percent.
The reconstruction project began on Nov. 14, 2005, and is currently on schedule. The contract called for the widening of the 3,800-ft. (1,158 m) main bridge, as well as the replacement of an intersecting ramp that ties into the bridge. The first five spans of the main deck will be replaced, but the remaining grid deck will remain in place. It will be overlaid with bituminous concrete. Finally, new sidewalks will be added, and the entire bridge will be repainted. Because of the existing lead paint, substantial containment of the bridge will be necessary during the abrasive blasting.
“There is a considerable amount of new fabricated structural steel that replaces deteriorated or obsolete members,” said Douglas W. Aiken, construction manager of the Allegheny County Department of Public Works. “The rehabilitation requires 1.8 million pounds of fabricated structural steel.”
Aiken noted that the project is unique from others he has worked on because of its proximity to a busy shopping complex, as well as dealing with four municipalities that have input into the project.
“The bridge spans over the Waterfront, a fairly new shopping and entertainment complex,” he said. “This requires cooperation from many sources.”
According to Aiken, construction is taking place in phases to allow two lanes of vehicular traffic to use the bridge during the project. In addition, at least one sidewalk must remain open across the bridge at all times.
“On the southern end and adjacent to the waterfront, the bridge spans over three Norfolk Southern lines and one CSX railroad line,” he said. “On the northern end, the bridge spans three CSX railroad lines as well.”
A total of 74 people are assigned to the project. Major subcontractors include Avalotis Painting, Verona, PA, for painting; Zavala Inc., Pittsburgh, for electrical systems; Lindy Paving for bituminous concrete installation; Structural Services Inc. for SIP deck pans; and Protections Services, which installed and maintains the MPT control devices.
Aiken noted that most of the equipment used on the job is owned, with only the large specialty equipment requiring rental. The list includes six Genie personnel lifts, a 200-ton (181.4 t) Manitowoc crane, an Ingersoll Rand 875 cfm air compressor, a Watson drill rig, a 300-ton (272.1 t) hydraulic crane, Cat backhoes, Bidwell finishing machines, and a 150-ft. (45.7 m) concrete pump.
The original bridge in the area was built in 1894 and was called Brown’s Bridge. It required four piers, and also had a low deck height that caused problems for river traffic. In addition, the approach to the bridge was problematic, involving a steep hill and railroad tracks. When 50,000 residents signed petitions demanding replacement, the work was commissioned.
Construction of the Homestead High Level Bridge began in September 1935. Its name was derived from the fact that the structure was built at a higher level than the original. The bridge was the first to be built using a Wichert truss design, which uses a quadrilateral shape over each support. PghBridges.com noted that the design uses a cantilever spandrel-braced deck arch, which is not a true arch bridge.
“The curved lower chord gives the bridge the form of an arch, but it does not rely on arch action to carry the load. The open diamond panel above each pier is the easily recognized mark of this truss type; without a vertical truss member in this hinged location. Before the use of computers, the interaction of forces on spans, which crossed multiple supports, was difficult to calculate. One solution to the problem was developed by E.M. Wichert of Pittsburgh in 1930. By introducing an open, hinged quadrilateral over the intermediate piers, each span could be calculated independently.”
The main span of the Homestead High Level Bridge was 516.3 ft. (157.4 m), with a vertical clearance of 109.3 ft. (33.3 m). The total construction cost at the time was $2.8 million.
In 2002, the bridge was renamed the Homestead Grays Bridge in honor of the Negro National League baseball team, the Homestead Grays. The Grays was one of two Pittsburgh teams in the league, and won 10 pennants and three World Series. The other Pittsburgh team was the Pittsburgh Crawfords. CEG