POINT PLEASANT BRIDGE COLLAPSE
GROUP 19
CLAIRE LYNCH
SARAH FINNEGAN
AOIFE DONNELLY
ANDREW MANNION
INTRODUCTION
The Point Pleasant Bridge carried US Route 35 and spanned over the Ohio River
connecting Point Pleasant, West Virginia and Kanauga, Ohio. It was constructed in
1928 by the General Corporation and the American Bridge Company and was known
as the Silver Bridge as it was the countries first and in the end, only aluminium
painted bridge.
DESIGN OF THE BRIDGE
The bridge spanned approximately 680m including approaches, which was made up
of a 213m centre span and 115m side spans. It was designed under the specifications
set out by the American Society of Civil Engineers. It had 2 lanes over 6.7m of
roadway and had one five-foot footpath. The bridge was a suspension bridge with
“eye-bars” chained together instead of the conventional wire cables. These eyebars
were linked together in pairs with massive pins to make chains. The length of each
chain varied depending on where it was located on the bridge.
To ensure these eye-bar pairs could hold the c. 1.8 million kg load stress that
they would be subject to, the American Bridge Company developed a new heattreated Carbon Steel to use on the construction. This new steel would allow the
individual members of the bridge to handle more stress. Along with the two eye-bars
sharing the load, the steel could easily handle the 1.8million kg load. These newly
treated chain steel eye-bars had an ultimate strength approx 30.7kg/m2 with an elastic
limit of 20.5kg/m2 along with a maximum working stress of 14.6kg/m2.
The anchorage design needed to be innovative because Bedrock was only
found at a considerable depth, making the ordinary gravity type anchorage
impractical. An unusual anchorage was designed consisting of a reinforced concrete
trough 61m long and 10.4m wide filled with soil and reinforced concrete. The huge
trough was supported on 0.4m octagonal reinforced concrete piles in which the cable
pull was resisted by the weight of the anchorage and by sharing the halves of the
piles.
Another unique design technique used on the Silver Bridge was the 'Rocker'
towers. The towers, which had a height of over 40m, allowed the bridge to move due
to shifting loads and changes in the chain lengths due to temperature variations. This
was done by placing a curved fitting next to a flat one at the bottom of the piers. The
rocker was then fitted with dowel rods to keep the structure from shifting horizontally.
With this type of connection, the piers were not fixed to the bases.
WHAT HAPPENED AND CONSEQUENCES
At 5pm on December 15 1967 the Point Pleasant Bridge collapsed claiming 46 lives
and injuring 9. Along with the numerous fatalities, a major transportation route
connecting West Virginia and Ohio was rendered useless. A cleavage fracture in the
limb of eye-bar 13 at joint C13N was followed by a ductile fracture near the pin.
Unable to support the entire weight of the structure the chain on the opposite side of
the bridge failed leading to, beginning on the Ohio side span and moving eastward
toward the west Virginia shore complete structural collapse in less than one minute.
An identical bridge nearby was subsequently closed immediately and eventually
destroyed and replaced. In 1969 a new bridge was completed just south of the
infamous Point Pleasant Bridge as a replacement.
Although the collapse of the bridge was a complete failure there were a
number of positive consequences. The existence of corrosion fatigue and stress
corrosion cracking was brought to the attention of engineers, thus resulting in
extensive research into such matters. New detection devices were developed to enable
early detection of minute cracks and, rehabilitation of structures is now commonplace
as a result of corrosion management. The investigation into the collapse of the bridge
highlighted the importance of research into new materials and their properties and
design strengths.
As a consequence of the collapse a number or recommendations were made by
the safety board. Some of the most important being
 Identification of bridge building materials susceptible to slow flaw
growth by any suspected mechanisms
 Determination of critical flaw size under various stress levels in bridge
building materials
 Development of inspection equipment capable of detecting near
critical flaws in bridges
 Develop standards for the qualification of materials for future bridges
 Devise techniques for the repair and protection of bridges damaged by
internal flaws
TECHNICAL FACTORS CONTRIBUTING TO THE DISASTER
The final analysis which was conducted by the U.S. Department of Transportation
concluded that the failure of the number 13 eye-bar pin on the north side had caused
the eye-bar chain to drop below the roadway on the upriver side of the bridge. As a
consequence the south eye-bar chain was unable to support the weight of the whole
structure and failure ensued.
The failure of the lower limb of the eye-bar can be attributed to a minute crack
formed during casting of the steel eye-bar. Over the bridges life-span stress corrosion
(cracking induced by the combined influence of tensile stress and a corrosive
environment) and corrosion fatigue (rupture of the protective passive film of a
material as a result of the combined action of alternating or cyclical stresses and a
corrosive environment, allowing acceleration of failure) allowed the crack to grow
and become a critical size flaw. A cleavage fracture formed followed by ductile
failure near the pin.
Stress Corrosion Cracking (4)
Corrosion Fatigue (4)
The casting and heat treatment of the new carbon steel would have introduced
residual stresses possibly close to the yield stress of the steal and hence microscopic
cracks with an inter-granular morphology formed. This, coupled with the corrosive
environment to which the steal would have been subjected left it susceptible to stress
corrosion cracking. When the bridge was designed in 1927 this was an unknown
phenomenon in classes of bridge material used under conditions of exposure usually
encountered in rural areas. Because the bridge was subjected to alternating cyclical
stresses again with the existence of a corrosive environment, corrosion fatigue also
served to decrease the life span of the bridge. Again such a concept was unknown at
the time but material which can be considered to have an infinite life span can have its
stress limit lowered or completely removed by corrosion fatigue.
Because both corrosion fatigue and stress corrosion are promoted by stresses
in the structure the increased weight to which the bridge was subjected over its lifespan also contributed to the eventual collapse of the structure. The bridge was
designed to carry one third of the weight which it routinely carried at the time of the
collapse. Although the design engineers designed the bridge with a load increase in
mind they did not even contemplate that it would have been so great.
Another important cause was that the flaw was inaccessible to visual
inspection. Even if the flaw could have been accessed there was no detection
equipment available at the time which would have been capable of detecting such a
flaw. The eye-bar joint would have had to be disassembled to detect it.
HUMAN AND MANAGERIAL FACTORS
CONTRIBUTING TO THE DISASTER
As with many structural failures human and managerial factors contribute to the
disaster. In the case of pleasant point here are the major factors observed.


In calculations of the loadings of pleasant point the car loadings was based on
the modern car of the day i.e. a ford model T. Although these calculations
where correct for the time. No provision was made for heavier vehicles in the
future and in turn no provision was made to revise the loadings when cars
where 4 times heavier.
Although an in depth structural survey was carried out on December 21, 1951
Where Bridge Engineer L. L. Jemison, suggested the following to H. K.
Griffith, West Virginia State Maintenance Engineer:
1. Repairing the bridge seat of the upstream side of the Ohio Abutment.
2. Cutting Ventilator openings in all of the four anchor chambers and making
frames for same.
3. Encasing the anchor bars inside of the anchor chambers with concrete.
4. Restoring the disintegrated concrete of the piers, anchorages and retaining
walls.
5. Waterproofing the roadway of the anchorages and the approaches and
surfacing same with asphaltic concrete.
6. Cleaning and painting steel work where necessary.
7. Revising the Ohio approach to provide better returns.
8. Extending the sidewalk along the Ohio approach.
9. Removing the Toll House.
10. Revising the lighting control system.
11. Miscellaneous steelwork: Repair Railing, Clean out holes at bottom of
tower verticals, Furnishing and installing gutters under expansion devices,
Making and installing bird screens,
12. Restoring concrete around anchor bars removed for inspection (1).

No provision was made for the surveying of the structural steel members.
Which seems very strange as the steel chains where a vital structural steel
element.
A lack of human understanding of the corrosion and brittle nature of the new
Heat-treated carbon steel used in the structure was a major downfall in the
structure.
LESSONS TO BE LEARNED FROM THE DISASTER
Even though the collapse of the Silver Bridge was a disastrous engineering failure,
there were many positive lessons learned. The following are some of the lessons.

The first of which is that bridge inspections are crucial to prolonging a bridges
structural life. In fact in the case of the silver point bridge president Lyndon B
Johnson ordered regular structural inspections to be carried out. Especially on
the 1100 of the 1800 bridges designed to Model T loading parameters.

Secondly engineers are now more knowledgeable about corrosion fatigue and
stress corrosion, which allows better quality structures to be designed and built
due to pleasant points collapse. With today's technology, as well as better
design techniques and materials, there is hope that a bridge failure like
pleasant point can be avoided.

Innovative structural solutions should be monitored with great care and
monitored before, during and after construction. With pleasant point bridge it
was very innovative in three major regions
1. Foundations
2. Heat-treated carbon steel used in links
3. Rocker towers.
If the steel used in the pleasant point links was monitored and tested to a
greater extent the disaster could have been avoided. In short faith in new
materials should be monitored.

With Structures such as Point Pleasant bridge, it should be noted how crucial
single elements are to the structure as a whole and appropriate protection
measures should be taken.
REFERENCES
1. Letter of L. L. Jemison to H. K. Griffith, 21 December 1951, WV Department
of Transportation, State Archives, Charleston.
2. LeRose, C. “The Collapse Of The Silver Bridge” West Virginia Historical
Society Quarterly Volume XV, No.4 October, 2001
www.wvculture.org/history/wvhs1504.html Accessed 20/10/05
3. Highway Accident Report: Collapse of U.S. 35 Highway Bridge Point
Pleasant, West Virginia, December 15, 1967
www.ntsb.gov/publictn/1971/HAR7101.htm Accessed 22/10/05
4. Silver Bridge Collapse www.corrosion-doctors.org/Bridges/Silver-Bridge.htm
Accessed 22/10/05
5. Gordon, J.E. (1978) Structures or why things don’t fall down London: Penguin