The new Dick Henderson Bridge was constructed on existing piers across the Kanawha River in West Virginia. Photo by Ahmed N. K. Mongi, P.E.
After the cost of a wholly new bridge exceeds its budget, the West Virginia Department of Transportation develops a plan to construct a new superstructure on a set of existing piers.
December 17, 2013—When transportation officials in West Virginia thought about replacing the Dick Henderson Memorial Bridge across the Kanawha River in Kanawha County, they initially planned to construct an entirely new structure at another location along the river. But as the cost of that plan rose to more than $100 million, officials determined that they could save a significant amount of money and expedite construction by not only constructing the new bridge in the same location as the existing one—but by also reusing the existing piers.
The Dick Henderson Memorial Bridge was constructed in 1934 to connect the towns of St. Albans and Nitro, West Virginia. A Warren through truss, the 1,367 ft long, three-span bridge had two 10 ft wide vehicular lanes, carrying a spur of West Virginia Route 25. The bridge provided an important link between the two small towns, but its condition deteriorated through the years, and eventually a 12-ton weight limit was imposed. Although the bridge was eligible for listing in the National Register of Historic Places, it was deemed functionally obsolete and structurally deficient beyond repair. As a result, the West Virginia Department of Transportation (WVDOT) set out to replace the bridge, according to Brent Walker, the director of communications for the WVDOT.
The department considered constructing a new bridge at another location over the river, but meeting the minimal navigational clearance of more than 450 ft to accommodate the coal barges and recreational vessels that travel the waterway drove up the cost. That’s when officials examined the existing bridge more closely and determined that they could construct a new superstructure on the two existing in-water piers. “We approached the U.S. Coast Guard with the idea of replacing just the superstructure while maintaining the existing navigational clearance and maintaining the bridge as a connection between U.S. 60 to the south and West Virginia 25 to the north,” says Ahmed Mongi, P.E., the WVDOT’s structures project manager for the Dick Henderson Memorial Bridge project. “We thought that would allow us to get a practically brand new bridge while maintaining the same navigational clearance.”
The existing piers were jacketed in 12 in. thick concrete and
topped by new concrete pier caps. Photo by Ahmed N. K.
Once it had the Coast Guard’s approval, the WVDOT worked with the community to consider six different superstructure types, including a truss, a cable-stayed, and an extradosed bridge. From the selection the department chose a steel plate-girder bridge because it was the least expensive to construct and could be completed in the shortest amount of time. While a girder bridge doesn’t have the same appearance as a truss bridge, officials assured the community that the new bridge would still be eye-catching. “You always find historians who would prefer to maintain the existing appearance, but a truss on this site was slightly more expensive than a plate-girder bridge,” Mongi says. “We managed to convince them that a steel plate-girder bridge could also be made to look aesthetically pleasing.”
The WVDOT hired Michael Baker Corporation, a professional services firm headquartered in Moon Township, Pennsylvania, as the design consultant, and Kokosing Construction Company, a construction firm headquartered in Westerville, Ohio, as the construction contractor on the project. Both firms have offices in Charleston, West Virginia.
Crews began by rehabilitating and upgrading the two existing in-water piers to carry the new wider bridge and heavier loads, as well as to resist barge collision forces. The work involved jacketing the piers in a 12 in. thick layer of concrete on all sides and installing new footings on 10 1/4 in. diameter micropiles that descend to 60 ft. The existing bridge remained open to traffic throughout the work. “We were able to do the work on the existing piers the year before we constructed the superstructure, while traffic was on the existing bridge,” Walker explains. “As a result, we had to close traffic down on the bridge for just ten months during construction.”
High-strength steel girders measuring 11 ft deep minimized the
depth of the structure. Photo by Ahmed N. K. Mongi, P.E.
Following the pier work, the existing bridge was demolished. The main span was dismantled by crane, and controlled blasts took down the two side spans and their corresponding support structures. Once the old bridge was removed, new concrete pier caps were installed and work on the new bridge got under way. New abutments were constructed closer to the river than the old ones in order to shorten the length of the bridge. But soft ground conditions on either side of the river posed a challenge. To overcome the issue, ground stabilization structures—controlled modulus columns (CMCs) and mechanically stabilized earth walls—were used to form the abutments. It was an innovative solution because the WVDOT had never used CMCs on a project before, Mongi says.
In addition to requiring stabilization, the soft soil along the riverbanks limited the location of the abutments. As a result, the bridge has an uneven span arrangement: span one measuring 257 ft, span two (the main span) measuring 450 ft, and span three measuring 302 ft. “Ideally we would have preferred to have span one and span three both measure 257 feet, but we had stability issues so we had to lengthen span three,” Mongi explains. Overall, the new bridge is 1,009 ft long and 48 ft wide from curb to curb. It carries three 12 ft wide lanes—one of which is a turning lane—two 6 ft wide shoulders, and a 5 ft wide sidewalk.
High-performance steel girders measuring 11 ft in depth minimized the bridge’s profile. The bridge is highest at its center point, increasing in grade by 7.6 percent from abutments to the center in order to accommodate the navigational channel.
During construction, the girders were floated out on barges and cranes mounted on barges lifted them into place over the river. A concrete deck was then placed on top of the girders and lighting and other aesthetic features were incorporated into the structure.
Following just 10 months of construction, the superstructure was completed at the end of October, and the new bridge opened on November 1. The project cost $27 million, significantly less than the price tag for constructing an entirely new bridge. “We were able to replace the existing bridge while utilizing the existing substructure, and that allowed us to accomplish the goal of [reducing the project cost],” Mongi says. “Now the community has a new bridge that meets current design standards, including a suitable weight limit to sufficiently and effectively serve the residential, commercial, and business community.”