Silver Bridge

The Silver Bridge was built in 1928, and was an eyebar-chain suspension bridge. The bridge carried US-35 over the Ohio River, and connected Point Pleasant, West Virginia and Gallipolis, Ohio. It was officially named the Point Pleasant Bridge, but it was referred to as the Silver Bridge due to the color of it’s aluminum paint.

The bridge was originally designed as a wire-cable suspension bridge, but an eyebar chain design was bid as an alternate, and it came at a lower price. It was the first of its type in the United States, although this design is very similar to the chain-link suspension bridges that were being constructed at that time. The Silver Bridge’s anchorages were unique it the use of heat-treated eyebar chains. Each chain link consisted of a pair of bone-shaped bars, with pins connecting the links through eyes at the ends of the bars. These chains also constituted the upper chord of a Warren stiffening truss. It was noted that due to the configuration, it was impossible to make any adjustments in the chains, hangers or trusses after erection.

The bridge was purchased by the State of West Virginia in 1941, and the toll was removed at the end of 1951. The bridge was inspected by the private owner from 1928 to 1941, and were taken over by the state after the sale. These inspections followed the state standards, and were completed in 1959, 1963, and 1964. After the 1964 inspection, repairs were recommended, and were completed. Following the repairs, the bridge was inspected again in the summer of 1967.

The Silver Bridge collapsed on December 15, 1967 during heavy rush-hour traffic, sending 64 people into the freezing water and killing 46 of them. It was the deadliest bridge disaster in United States History.

After the collapse, the National Transportation Safety Board (NTSB) began an investigation into the collapse. It was concluded the that the cause of the collapse was “a cleavage fracture in the lower limb of the eye of eyebar 330 at joint C13N of the north eyebar suspension chain in the Ohio side span. The fracture was caused by the development of a critical-size flaw over the 40-year life of the structure as the result of the joint action of stress corrosion and corrosion fatigue.” It was also noted that the location of the crack was inaccessible to visual inspection, and could not have been detected without disassembly of the eyebar joint, which was a practical impossibility.

One of the key lessons from this bridge collapse was redundancy. The Silver Bridge was not a redundant structure since it was composed of only two pairs of eyebars. If either one of the eyebars failed, then the whole bridge would collapse. Following this collapse, engineers began building redundancy into bridges wherever possible.

The collapse of the Silver Bridge also paved the way for improved safety inspections for bridges. In 1968, the National Bridge Inspection Standards were approved by Congress. These standards are still used today.

There are currently plaques and memorials on both sides of the river. In addition, a lot of the concrete elements were left in the river, and can be seen from the Ohio side.