Schoharie Creek Bridge collapse
Encyclopedia
The Schoharie Creek Bridge was a New York State Thruway
bridge over the Schoharie Creek
near Fort Hunter
, in New York State. On April 5, 1987 it collapse
d due to erosion
at the foundations after a record rainfall. The collapse killed ten people.
The failure of the Schoharie Creek Bridge motivated the improvement in the development of bridge design and inspection procedures.
, (previously named The New York State Department of Public Works). The design described a 155 metres (508.5 ft) crossing consisting of five simply supported spans with nominal lengths of 30.5 metres (100.1 ft), 33.5 m (109.9 ft), 36.6 m (120.1 ft), 33.5 m (109.9 ft), and 30.5 m (100.1 ft). The bridge was supported with pier
frames along with abutments at each end. The pier frames were constructed of two slightly tapered columns with tie beams. The columns were fixed in place within a lightly reinforced plinth
positioned on a shallow, reinforced spread footing. The spread footing was to be protected with a dry layer of riprap
.
The superstructure
consisted of two longitudinal main girders with transverse floor beams. The skeleton of the bridge deck (200 millimetres (7.9 in) thick) was made up of steel stringers.
Construction began on February 11, 1953 by B. Perini and Sons, Inc.
was fully completed
The Schoharie Creek Bridge (NY 1020940, New York State bridge identification number), began full service beginning in October 1954.
In the spring and summer of 1955, the pier plinths began to show vertical cracks ranging from 3 millimetre, as a result of high tensile stresses in the concrete plinth. In 1957, plinth reinforcement was added to each of the four piers.
Almost a year later on October 16, 1955, the bridge was damaged by a flood
.
Pier three was the first to collapse, which caused the progressive collapse of spans three and four. Ninety minutes later pier two and span two collapsed. Two hours later pier one and span one shifted. A National Transportation Safety Board
investigation suggested that pier two collapsed because the wreckage of pier three and the two spans may have partially blocked the river, redirecting and increasing the velocity of the flow of water to pier two.
Six days later, 5 km (3.1 mi) upstream, a large section of the Mill Point Bridge collapsed. The bridge had been closed since the flood as a precaution that its foundations had also been eroded.
-semitrailer were on the bridge. Before the road could be blocked off, three more cars drove into the gap. During the following three weeks, nine bodies were recovered from the river. The body of the 10th victim was recovered in the Mohawk River in July 1989.
under pier three. The foundation of the pier was bearing on erodible soil, consisting of layers of gravel, sand and silt, inter-bedded with folded and tilted till. This allowed high velocity flood waters to penetrate the bearing stratum.
The area left around the footing was not filled with riprap stone, but instead was back-filled with erodible soil and topped off with dry riprap. Riprap protection, inspection, and maintenance were determined to have been inadequate.
The investigations showed that the scouring process under the piers began shortly after the bridge was built. At the time of the collapse, the upstream end of pier 3 fell into a scour hole approximately 3 metres (9.8 ft) deep. Investigators estimated that about 7.5 metre of the pier was undermined.
The design for the Schoharie Creek Bridge originally called for leaving sheet piles in place (which are used to keep water out of excavation areas during construction). The riprap would then have filled the area left between the pier footings and the sheeting. However, this sheeting was not left in place.
Another reason for the collapse was the weight of the riprap. The design specification called for riprap with 50 percent of the stones heavier than 1.3 kilonewtons (1,300 N), and the remainder between 0.44 kilonewton. Investigators found that heavier riprap weights of 4.4 kilonewton should have been specified.
Other considerations as to the cause of the collapse included design of the superstructure, quality of materials and construction, inspection and maintenance. Investigations found that these factors did not contribute to the collapse.
Twelve hours before the Schoharie Creek Bridge collapsed, due to heavy rainfall, the rush of water through the Blenheim-Gilboa Pumped Storage Power Project
40 miles (64.4 km) upstream hit a historic high. To cope with the overload, the dam released water into the Scholarie Creek according to the rate at which it was entering the reservoir from upstream. This was a possible contributing factor to the failure.
New York State Thruway
The New York State Thruway is a system of limited-access highways located within the state of New York in the United States. The system, known officially as the Governor Thomas E. Dewey Thruway for former New York Governor Thomas E. Dewey, is operated by the New York State Thruway Authority and...
bridge over the Schoharie Creek
Schoharie Creek
Schoharie Creek in New York, USA flows north from the foot of Indian Head Mountain in the Catskill Mountains through the Schoharie Valley to the Mohawk River. It is twice impounded north of Prattsville to create New York City's Schoharie Reservoir and the Blenheim-Gilboa Power Project.Two notable...
near Fort Hunter
Fort Hunter, New York
Fort Hunter is a hamlet in the town of Florida in Montgomery County, New York, on the Mohawk River at Schoharie Creek.In the 18th century, Fort Hunter was built as a fort near the location of one of the two primary Mohawk settlements. The Mohawk name for the village was rendered variously in...
, in New York State. On April 5, 1987 it collapse
Collapse
Collapse may refer to:* Collapse, the action a collapsible or telescoping object does* Collapse * Collapse * Collapse ** Cave-in is a kind of structural collapse** Collapse of the World Trade Center, a 2001 event...
d due to erosion
Erosion
Erosion is when materials are removed from the surface and changed into something else. It only works by hydraulic actions and transport of solids in the natural environment, and leads to the deposition of these materials elsewhere...
at the foundations after a record rainfall. The collapse killed ten people.
The failure of the Schoharie Creek Bridge motivated the improvement in the development of bridge design and inspection procedures.
Bridge design and construction
The final design for the bridge was approved in January 1952 by the New York State Department of TransportationNew York State Department of Transportation
The New York State Department of Transportation is responsible for the development and operation of highways, railroads, mass transit systems, ports, waterways and aviation facilities in the U.S...
, (previously named The New York State Department of Public Works). The design described a 155 metres (508.5 ft) crossing consisting of five simply supported spans with nominal lengths of 30.5 metres (100.1 ft), 33.5 m (109.9 ft), 36.6 m (120.1 ft), 33.5 m (109.9 ft), and 30.5 m (100.1 ft). The bridge was supported with pier
Pier
A pier is a raised structure, including bridge and building supports and walkways, over water, typically supported by widely spread piles or pillars...
frames along with abutments at each end. The pier frames were constructed of two slightly tapered columns with tie beams. The columns were fixed in place within a lightly reinforced plinth
Plinth
In architecture, a plinth is the base or platform upon which a column, pedestal, statue, monument or structure rests. Gottfried Semper's The Four Elements of Architecture posited that the plinth, the hearth, the roof, and the wall make up all of architectural theory. The plinth usually rests...
positioned on a shallow, reinforced spread footing. The spread footing was to be protected with a dry layer of riprap
Riprap
Riprap — also known as rip rap, rubble, shot rock or rock armour or "Rip-rap" — is rock or other material used to armor shorelines, streambeds, bridge abutments, pilings and other shoreline structures against scour, water or ice erosion.It is made from a variety of rock types, commonly granite or...
.
The superstructure
Superstructure
A superstructure is an upward extension of an existing structure above a baseline. This term is applied to various kinds of physical structures such as buildings, bridges, or ships...
consisted of two longitudinal main girders with transverse floor beams. The skeleton of the bridge deck (200 millimetres (7.9 in) thick) was made up of steel stringers.
Construction began on February 11, 1953 by B. Perini and Sons, Inc.
Service
The bridge was partially opened during the summer of 1954 before constructionConstruction
In the fields of architecture and civil engineering, construction is a process that consists of the building or assembling of infrastructure. Far from being a single activity, large scale construction is a feat of human multitasking...
was fully completed
The Schoharie Creek Bridge (NY 1020940, New York State bridge identification number), began full service beginning in October 1954.
In the spring and summer of 1955, the pier plinths began to show vertical cracks ranging from 3 millimetre, as a result of high tensile stresses in the concrete plinth. In 1957, plinth reinforcement was added to each of the four piers.
Almost a year later on October 16, 1955, the bridge was damaged by a flood
Flood
A flood is an overflow of an expanse of water that submerges land. The EU Floods directive defines a flood as a temporary covering by water of land not normally covered by water...
.
Collapse
On the morning of April 5, 1987, during the spring flood, the Schoharie Creek Bridge collapsed. A snowmelt combined with rainfall totaling 150 mm (5.9 in) produced an estimated 50 year flood.Pier three was the first to collapse, which caused the progressive collapse of spans three and four. Ninety minutes later pier two and span two collapsed. Two hours later pier one and span one shifted. A National Transportation Safety Board
National Transportation Safety Board
The National Transportation Safety Board is an independent U.S. government investigative agency responsible for civil transportation accident investigation. In this role, the NTSB investigates and reports on aviation accidents and incidents, certain types of highway crashes, ship and marine...
investigation suggested that pier two collapsed because the wreckage of pier three and the two spans may have partially blocked the river, redirecting and increasing the velocity of the flow of water to pier two.
Six days later, 5 km (3.1 mi) upstream, a large section of the Mill Point Bridge collapsed. The bridge had been closed since the flood as a precaution that its foundations had also been eroded.
Casualties
At the time of the collapse, one car and one tractorTractor
A tractor is a vehicle specifically designed to deliver a high tractive effort at slow speeds, for the purposes of hauling a trailer or machinery used in agriculture or construction...
-semitrailer were on the bridge. Before the road could be blocked off, three more cars drove into the gap. During the following three weeks, nine bodies were recovered from the river. The body of the 10th victim was recovered in the Mohawk River in July 1989.
Causes of failure
It was concluded that the bridge collapsed due to extensive scourBridge scour
Bridge scour is the removal of sediment such as sand and rocks from around bridge abutments or piers. Scour, caused by swiftly moving water, can scoop out scour holes, compromising the integrity of a structure....
under pier three. The foundation of the pier was bearing on erodible soil, consisting of layers of gravel, sand and silt, inter-bedded with folded and tilted till. This allowed high velocity flood waters to penetrate the bearing stratum.
The area left around the footing was not filled with riprap stone, but instead was back-filled with erodible soil and topped off with dry riprap. Riprap protection, inspection, and maintenance were determined to have been inadequate.
The investigations showed that the scouring process under the piers began shortly after the bridge was built. At the time of the collapse, the upstream end of pier 3 fell into a scour hole approximately 3 metres (9.8 ft) deep. Investigators estimated that about 7.5 metre of the pier was undermined.
The design for the Schoharie Creek Bridge originally called for leaving sheet piles in place (which are used to keep water out of excavation areas during construction). The riprap would then have filled the area left between the pier footings and the sheeting. However, this sheeting was not left in place.
Another reason for the collapse was the weight of the riprap. The design specification called for riprap with 50 percent of the stones heavier than 1.3 kilonewtons (1,300 N), and the remainder between 0.44 kilonewton. Investigators found that heavier riprap weights of 4.4 kilonewton should have been specified.
Other considerations as to the cause of the collapse included design of the superstructure, quality of materials and construction, inspection and maintenance. Investigations found that these factors did not contribute to the collapse.
Twelve hours before the Schoharie Creek Bridge collapsed, due to heavy rainfall, the rush of water through the Blenheim-Gilboa Pumped Storage Power Project
Blenheim-Gilboa Pumped Storage Power Project
The Blenheim-Gilboa Pumped Storage Power Project is a pumped-storage hydroelectricity plant in the Catskill Mountains of New York State. The plant is part of the New York Power Authority, and can generate over 1,000,000 kilowatts of electricity, all of which is sent to New York City in the case of...
40 miles (64.4 km) upstream hit a historic high. To cope with the overload, the dam released water into the Scholarie Creek according to the rate at which it was entering the reservoir from upstream. This was a possible contributing factor to the failure.
Further reading
- Boorstin, Robert O. (1987). Bridge Collapses on the Thruway, Trapping Vehicles, Volume CXXXVI, No. 47,101, The New York Times, April 6, 1987.
- Huber, Frank. (1991). “Update: Bridge Scour.” Civil Engineering, ASCE, Vol. 61, No. 9, pp 62–63, September 1991.
- Levy, Matthys and Salvadori, Mario (1992). Why Buildings Fall Down. W.W. Norton and Company, New York, New York.
- National Transportation Safety Board (NTSB). (1988). “Collapse of New York Thruway (I-90) Bridge over the Schoharie Creek, near Amsterdam, New York, April 5, 1987.” Highway Accident Report: NTSB/HAR-88/02, Washington, D.C.
- Springer Netherlands. International Journal of Fracture, Volume 51, Number 1 September 1991. "The collapse of the Schoharie Creek Bridge: a case study in concrete fracture mechanics"
- Palmer, R., and Turkiyyah, G. (1999). “CAESAR: An Expert System for Evaluation of Scour and Stream Stability.” National Cooperative Highway Research Program (NCHRP) Report 426, Washington D. C.
- Shepherd, Robin and Frost, J. David (1995). Failures in Civil Engineering: Structural, Foundation and Geoenvironmental Case Studies. American Society of Civil Engineers, New York, New York.
- Thornton, C. H., Tomasetti, R. L., and Joseph, L. M. (1988). “Lessons From Schoharie Creek,” Civil Engineering, Vol. 58, No.5, pp. 46–49, May 1988.
- Thornton-Tomasetti, P. C. (1987) “Overview Report Investigation of the New York State Thruway Schoharie Creek Bridge Collapse.” Prepared for: New York State Disaster Preparedness Commission, December 1987.
- Wiss, Janney, Elstner Associates, Inc., and Mueser Rutledge Consulting Engineers (1987) “Collapse of Thruway Bridge at Schoharie Creek,” Final Report, Prepared for: New York State Thruway Authority, November 1987.