US 321 southbound bridge over Lake Hickory to undergo structural repairs
CALDWELL COUNTY, NC (September 5, 2021) — The NCDOT has plans to make structural repairs to the US 321 southbound bridge over Lake Hickory in the spring of 2022.
Even though the replacement of the bridge is planned with the up-coming project to widen US 321 between Hickory and Lenoir, the conditions of the deck and the steel beams warrant work to continue to maintain the bridge in safe operating condition until the new bridge is placed in service.
This work will help to extend the serviceable life of the bridge and continue to keep the bridge in a safe condition until the replacement is complete. In addition, this work will reduce the continued maintenance work necessary for the operation of the bridge until replacement.
The US 321 southbound bridge (#367) was built in 1962 and was last inspected on April 22, 2020.
The bridge qualifies as being Structurally Deficient (due to conditions of the bridge deck and steel beams) and Functionally Obsolete (due to the deck geometry and narrow width).
The nature and scope of the work to address the steel beams and deck is beyond the capacity of Division 11 bridge maintenance forces to complete, while also continuing to properly maintain other bridges, so the repair project (# U-4700AA) is being designed to be let to contract in December of 2021. The scope of work for the repair project encompasses two main tasks:
• Due to almost 60 years of water and deicing salt and brine accessing the ends of the steel beams through the bridge deck joints, rust and corrosion has caused reduction in the size of the steel beams at interior substructure supports. Where excessive corrosion has occurred, the steel beams will have portions of the beams cut out and replaced with new portions or steel plates that will be added to the existing beams. After the beam repairs are made, the steel beam repair areas and other areas that have severely deteriorated paint will have a new paint system applied.
• An asphalt wearing surface was placed on the deck approximately 18 years ago, and there are numerous locations where potholes have developed in the asphalt, requiring repairs. This is an on-going issue. Additionally, the placement of the asphalt at the existing bridge joints was a difficult challenge; conditions at the bridge joints have resulted in a poor ride and water is allowed to access the steel beams below. The asphalt wearing surface will be removed and a new concrete wearing surface will be placed, along with new bridge deck joints and seals. This will address pothole issues and provide for a better ride on the deck. Additionally, this will allow installation of a better bridge deck joint and joint seal, resulting in a better ride and reduction of water through the joints to the steel beams.
The US 321 northbound bridge (#366) over Lake Hickory was built in 1983.
The NCDOT anticipates completing the repairs in Summer of 2022.
Information provided by NCDOT Structures Management Unit.
NCDOT follows National Bridge Inspection Standards and ensures each bridge is inspected at least every two years.
As of March 2021, about 1,100, or 8.2 percent, of the state’s bridges were considered in poor condition.
Poor condition bridges are safe; however, they have components that are deteriorating. They require significant maintenance to remain in service and might require limits on vehicle weights. To fully address the issues on a poor condition bridge, extensive rehabilitation or replacement is usually required.
Another commonly used term is functionally obsolete. A functionally obsolete bridge no longer meets the demands of the traffic using it. These bridges are safe but need to be improved or replaced due to narrow lanes, low height clearances or have posted weight limits.
For NCDOT to replace all poor condition bridges, it would cost more than $3.8 billion.