Wikibooks

Professionalism/Collapse of the “Swinging Bridge,” Heber Springs, Arkansas

< Professionalism

Winkley Bridge

edit

History

edit

In 1912, the county of Cleburne in Arkansas recognized the need for a bridge at Turney’s Ferry to connect the eastern section of the county to the county seat of Heber Springs. The county also recognized the need for two other bridges at different locations, Miller and Tumbling Shoals. Previously, only ferries served the community’s needs. A request was sent out for proposals on steel bridge designs with the specifications according to the commissioners of the county. No bids were received for this design. The commission then decided that a suspension wire bridge would suit their needs just as well as a steel bridge. The commission stated “It will be impracticable . . . to undertake the erection of steel bridges, because of their immense cost at the places selected, and we are convinced that suspension wire Bridges will, when properly built, serve the purposes of our people in a satisfactory way.” Once proposals were sent out for a suspension wire bridge, the commission did receive a few bids. The winning bid was to contractor Harry Churchill. His bid for the three bridges was $26,000.The commissioners, "not feeling justified in accepting said bid," negotiated with Churchill and closed the deal at $24,000. The cost of the bridge at Turney’s Ferry was proposed to be $9,670. Churchill started construction of the bridge in late May of 1912 and finished it on November 1, 1912. The bridge design was a streamlined suspension bridge. The two towers and deck of the bridge were both made of wood. The bridge was 550 feet long with the middle span being 450 feet. The deck was 10 feet wide. In 1949 the wooden towers were replaced with steel towers. In 1968, a delegation of Cleburne County citizens asked the State Highway Department to replace the Winkley Bridge. The delegation wanted to make the bridge a tourist attraction. The proposal was eventually approved, and the bridge was programmed for replacement. In 1972, a new bridge was constructed a few hundred feet downstream from Winkley Bridge. Since the new bridge served the community’s needs, Winkley Bridge was closed to vehicular traffic, thus making it open only for pedestrians.1 In 1985, it was listed on the National Register of Historic Places.2 Throughout the lifespan of the bridge, a noticeable sway could be seen and felt on the bridge. This is how the bridge earned the nickname “The Swinging Bridge”. It was a popular pastime for people to go on the bridge and feel the sway and possibly even try to make it swing a little more. The bridge remained a popular tourist attraction until October 28, 1989. A church group of about forty people decided to swing the bridge from side to side. The bridge collapsed, killing 5 people and injuring dozens. 3

Collapse

edit

Bridge Details

edit

The bridge deck was supported by two cable systems running the length of the deck on either side of the bridge. Each cable system was 5" in diameter, made up of 1/8" diameter cables bundled together. Both systems contained metal hangers spaced approximately every five feet that were attached to the bridge deck via metal plates on the underside of beams1.

Inspection

edit

In 1982 Cleburne County commissioned a team of engineers to inspect Winkley Bridge's structural condition. While the team found rust to be present on the outer cables of the bundle, the inner cables were deemed rust free, and thus the investigative team concluded that the bridge was safe for pedestrian use for another 50 to 100 years. The lead engineer, however, did recommend that a corrosive resistant coating be applied to all of the bridge's cables and also suggested that an ultra-sound be conducted as to have a more complete analysis of the bridge cables. Despite those recommendations, Cleburne County never orders such tasks to be completed.4

Cause

edit

The bridge collapsed due to lateral outward swinging5. In short, the pedestrians on the bridge were swinging it from side to side. In doing so, this exerted greater stress and strain on the cable systems running along the length of the deck. As the bridge deck swung further out from side to side, the cables began to weaken until one of the systems snapped. Upon snapping, the deck's weight cause it to begin to flip, causing the remaining cable system to snap as it was loaded beyond capacity. After the second cable system failed, the deck turned completely over as it fell into the Little Red River below. In the aftermath of the collapse the investigating engineer from Little Rock, Arkansas, Frank Allison, cited rust as a contributing factor to the cable failure6. He stated that in some areas along the cable system, the individual cables on the exterior of the bundle had completely rusted through. Once cables have rusted to the point of separation, they are essentially useless. This lowers the cable system's calculated load capacity and no longer provides adequate support for the bridge deck.

Unanticipated Results

edit

As was demonstrated in the case of the Winkley Bridge, a structure's intended use may not always be its actual use. The suspension bridge over the Little Red River was originally designed to allow vehicular access to Heber Springs from the east side of the county. Once closed to vehicles in 1972, the bridge was deemed acceptable for pedestrian use for the purpose of crossing the river. An engineer could not have anticipated groups of people intentionally causing the suspension bridge to swing from side to side.

The Millennium Bridge in London, England was a unique style suspension bridge that opening in 2000. The bridge's cables run underneath the bridge as opposed to along the top attaching to towers as many traditional bridges do. The bridge was closed two days after it opened, and was not reopened in 2002, after pedestrians complained about the unexpected swaying they felt when progressed over the River Thames. This bridge sway was attributed to oscillations caused by pedestrian foot traffic. Walking across the bridge initiated the swaying motion and as pedestrians continued to cross, the swaying's amplitude grew. The solution was resolved by adding dampers to the bridge that absorbed pedestrians' foot vibrations, and thus reducing the amount of sway.

The Tacoma Narrows Bridge disaster resulted in an effort to reduce the cost of building a new bridge. The original proposal employed a truss system to support the deck that would allow wind to pass through them. The final design, however, used girders in place of the trusses. Girders are long beams with no openings that enabled the wind forces to push the bridge inducing the abnormal deck movement, and ultimately causing its collapse on November 7, 1940.

Carlton v. Cleburne County

edit

A class action lawsuit, which was comprised of complaints from victims of the bridge collapse and families of the deceased was filed under the name of Jason Carlton against Cleburne County, Arkansas and the Quorum Court members—the same group that first initiated the engineering tests to determine if the bridge was safe and then the same group that did not pursue further investigation of the bridge cables per the engineer’s request. The plaintiffs argued that the victims of the bridge collapse were denied their due process rights—rights guaranteed to a person by all levels of government. In this case, they claimed they were denied of their safety. This lawsuit also encompassed a complaint against the nearby Swinging Bridge Resort and its individual owners, which had a bridge easement on its property, claiming negligence in failing to warn the victims of an “ultra-hazardous danger.” The Honorable George Howard, Jr., the Arkansas District Judge, ruled in favor of the defendants. The plaintiffs appealed and the case was brought to the Arkansas Circuit courts, in front of Judges Wollman, Ross and Murphy. On August 21, 1996, nearly 7 years after the Winkley Bridge collapse, the circuit court judges ruled in favor of the defendants again. The Circuit Court concluded that The Swinging Bridge Resort and its owners were immune from a lawsuit under Arkansas’ Recreational Use Statue, stating that the risk could have been avoidable by exercise of reasonable care. Thus, the court ruled that the collapse was the responsibility of those on the bridge rather than the negligence of the owners. The Court decided in favor of Cleburne County on the grounds that Cleburne County does not need to warn citizens about possible dangers. Specifically, the Court stated that Cleburne County protected by the language of Arkansas’ Due Process Clause, which states “[the] clause is phrased as a limitation on the State’s power to act, not as a guarantee of certain minimal levels of safety and security.”4

Ethics

edit

This court case brings up several ethical issues. Cleburne County had information that citizens regularly swung the bridge for recreation, much like the aforementioned Millennium Bridge. Additionally, the County knew that there could be potentially catastrophic results from swinging the bridge. Yet, no preventative measures were taken to ensure that pedestrians did not swing the bridge. The County did not place any signs prohibiting swinging the bridge or warning against the possible dangers of swinging the bridge. Additionally, the Arkansas Quorum Courts did not heed the engineer’s recommendation of further investigation or to apply a corrosive resistant coating to the cables. Yet, from our research there was no resistance to the Quorum Court’s decision and no attempt to really push for an ultrasound of the bridge cables. We see in this case that once the bridge was deemed as “safe,” no further investigation was taken by nearly 70 years of minimal problems from the bridge. This level of confidence caused by so many years of bridge service could have been the reason that the Quorum Court members opted to not spend the money for further investigation of the bridge considering that it was only carrying pedestrian traffic compared to vehicular traffic. Unfortunately, there is no way of knowing whether or not warning signs or further pleas to investigate the bridge cables would have prevented this disaster. This then begs the question, how much of safety is the responsibility of individuals versus an institution? This is a unique case compared to the other ethical cases we have seen in that there are no whistle blowers in this case.

See Also

edit

References

edit
Retrieved from "https://en.wikibooks.org/w/index.php?title=Professionalism/Collapse_of_the_“Swinging_Bridge,”_Heber_Springs,_Arkansas&oldid=2483160"