Evaluation of factual materials and recommendations concerning the collapse of the Mianus River Bridge

              NATIONAL TRANSPORTATION SAFETY . BOARD
in the Matter of:
Investigation of Collapse of
a Section of the 1- 95 Bridge
Oyer the Mianus River,
Greenwich, Connecticut,
June 28, 1983.
Case No. HY- 446
EVALUATION OF FACTUAL MATERIALS
AND RECOMMENDATIONS CONCERNING THE
COLLAPSE OF THE MIANUS' RIVER- BRIDGE
>
V \ ^ /
3ubir. ittea by:
TIPPETTS- ABEETT- McCARTHY -
The TAMS Building
655 Third Avenue
New York, N. Y. 10 017
( 212) 867- 1777
Dated: December 19, 1983
Connecticut state Library
0231 00122 2624
BEFORE THE
NATIONAL TRANSPORTATION SAFETY BOARD
In the Matter of:
Investigation of Collapse of
a Section of the 1- 95 Bridge
Over the Mianus River,
Greenwich, Connecticut,
June 28, 1983.
Case No. HY- 446- 83
EVALUATION OF FACTUAL MATERIALS
AND RECOMMENDATIONS CONCERNING THE
COLLAPSE OF THE MIANUS RIVER BRIDGE
Submitted by:
TIPPETTS- ABBETT- McCARTHY- STRATTON
The TAMS Building
655 Third Avenue
New York, N. Y. 10017
( 212) 867- 1777
Dated: December 19, 1983
TABLE OF CONTENTS
Page
INTRODUCTION ." 1
PART I - THE MIANUS RIVER BRIDGE WAS
DESIGNED IN ACCORDANCE WITH ALL
APPLICABLE DESIGN REQUIREMENTS .... 3
A. The Design For the Mianus River
Bridge Was Prepared In Accordance
With Specifications and Alignments
Supplied By the State of Connecticut . . . . 5
B. The Bridge Was Designed Consistent
With Engineering Theories and
Techniques Prevalent In the 1950' s 6
C. The Pins Used In the Pin- and- Hanger
Assemblies Supporting the Bridge
Were Correctly Sized, Based on
Allowable Stresses That Were
Correctly Selected >. 9
D. The Pin- and- Hanger Assembly and
the Retaining Plate and Bolt
Configuration Were Correctly
Selected In Accordance With
Contemporaneous Design Standards 11
E. The Collapse of the Mianus River
Bridge Was Not Related to Design
and Most Probably Was Caused By
Gradual, Unchecked Corrosion and
Forces Due to Ice Formation. 13
F. The Differences Among the
Allowable Stress Used In the
Pin Design, as Originally
Designed, the Actual Stress
In the Pin, and the Allowable
Stress Which Would Be Required
Using Current Design Standards,
Did Not Contribute to the
Mechanism of the Accident 18
i
G. The Design Criticisms Offered
By the State are Factually
Unsupported and Should Be
Disregarded 18
1. Out- of- Plane Distortions 19
2. Drainage 21
3. ConnDOT " Internal Review"
( Exhibit VI- 43) 23
4. S. T. Hudson Report
( Exhibit VI- 72) 24
PART II - WITH A MORE EFFECTIVE ORGANIZATION,
THE STATE WOULD HAVE RECOGNIZED THE EXISTENCE
OF PROBLEMS AND WOULD HAVE DETECTED AND HALTED
THE CORROSION WHICH LED TO THE COLLAPSE OF THE
MIANUS RIVER BRIDGE . 27
A. Effective Inspection Techniques Were
Available to Detect the Deterioration
Which Ultimately Caused the Collapse
of the Mianus River Bridge 27
1. Following the collapse of the
Silver Bridge in 1967, the
states knew that hard- to- inspect
components such as pin- and-hanger
assemblies required
special inspection because they
were essential to a bridge's
continued structural integrity 27
2. The numerous inspection manuals
and guides that were developed
following the collapse of the
Silver Bridge highlighted the
importance of detecting the
problems which contributed to
the collapse of the Mianus
River Bridge 30
B. ConnDOT's Organizational Problems
Prevented Effective Application of
Available Inspection Techniques. 40
1. ConnDOT has specifically
incorporated the generally
applicable bridge inspection
manuals into its own internal
inspection requirements 40
ii
2. If ConnDOT had followed its own
established procedures, it would
have responded to the visible
a. The progress and results of
each of the identified
mechanisms of deterioration
were detectable through
thorough routine inspection
techniques . . . 42
b. ConnDOT's organizational
structure did not facil-itate
the implementation of
an effective program of
integrated inspection and
maintenance 46
effects of corrosion 42
PART III - RECOMMENDATIONS 53 ^
A. Accident Investigations 53
B. Inspection and Design 53
C. Conduct of Inspections 53
D. Organization of Inspection 55
CONCLUSION 56
iii
BEFORE THE
NATIONAL TRANSPORTATION SAFETY BOARD
In the Matter of:
Investigation of Collapse of
a Section of the 1- 95 Bridge
Over the Mianus River,
Greenwich, Connecticut,
June 28, 1983.
Case No. HY- 446- 83
EVALUATION OF FACTUAL MATERIALS
AND RECOMMENDATIONS CONCERNING THE
COLLAPSE OF THE MIANUS RIVER BRIDGE
On June 28, 1983, at approximately 1: 30 A. M., a
section of the bridge carrying Interstate Highway 1- 95 over
the Mianus River in Greenwich, Connecticut, collapsed. The
National Transportation Safety Board ( the " NTSB") convened
an investigation into the collapse, and the NTSB's Board of
Inquiry ( the " Board") held four days of hearings on Sep-tember
19- 22, 1983. This document is filed by Tippetts-
Abbett- McCarthy- Stratton (" TAMS"), which was afforded party
status in that hearing by Order of Board Chairman Bursley
dated August 16, 1983.
INTRODUCTION
TAMS is a professional architectural and engineer-ing
firm, with its principal office in New York City. TAMS
now employs more than 500 people and has more than 40 years
of experience in transportation, water resources, architec-ture
and planning, environmental engineering and engineering
management. Of particular relevance to this proceeding,
TAMS has extensive experience in the design and engineering
of highways and bridges. It has designed more than 2000
bridges, and has inspected more than 1600 bridges.
This report, which reflects TAMS's expertise and
experience, has been prepared to assist the Board in eval-uating
the evidence gathered in its investigation and to
suggest recommendations based upon that evidence. To this
end, this submission is organized into three parts. The
first part addresses the original design of the Mianus River
Bridge and its consistency with all applicable design stand-ards
and Connecticut State specifications and requirements
in 1954 and 1955, as well as the role of corrosion or ice
formation as the possible cause of the collapse. This part
also demonstrates how design standards have evolved since
that time. The second part addresses the relationships
between the collapse of the bridge and applicable inspection
requirements and procedures as they existed and have evolved
through the 25- year period since the bridge was constructed.
The third part presents for the Board's consideration TAMS's
recommendations based upon the foregoing discussion.
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PART I
THE MIANUS RIVER BRIDGE WAS
DESIGNED IN ACCORDANCE WITH ALL
APPLICABLE DESIGN REQUIREMENTS
Duri- ng its lifetime, any bridge is conceived,
designed, constructed, and inspected and maintained. The
Board's objective in this proceeding is to identify where,
if at all, in this process a flaw occurred which allowed the
Mianus River Bridge to collapse. Based upon the evidence
gathered by the Board, this section concludes that the col-lapse
was caused by flaws in the. inspection- maintenance
stage.
The determination of causation is best made in the
framework of the conditions which existed in the 1950' s.
This period witnessed the infancy of the surface transpor-tation
system which would later develop into the interstate
system. Of the 550,000 bridges in the United States now,
more than 250,000 bridges have been built since the 1950" s.
The Mianus River Bridge was designed and built between 1954
and 1958.
The technical environment has changed signifi-cantly
since that time. Communication among practicing
engineers occurred then either through technical research
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papers or organized meetings. Compared to the current fund-ing
levels, the funds for bridges available to the Bureau of
Public Roads, predecessor to the Federal Highway Admin-istration
(" FHWA"), and most States were extremely limited.
The concept of fracture- critical bridges was not a
design consideration at the time the Mianus River Bridge was
built. Knowledge of the effects of fatigue stresses was
limited or non- existent. Redundancy was not considered an
important element of design. Methods of three- dimensional
analysis were not practical, and the electronic computer was
not widely available for bridge design. Thus, engineers
generally employed hand calculations in designing bridges.
The bridge design performed by TAMS involved more than 900
calculation sheets.
Criticisms of the design, as presented through
testimony to the Board and in reports submitted to the State
of Connecticut ( the " State") by its consultants, ignored the
fact that the bridge design standards prevailing when the
bridge was designed and constructed differed significantly
from current standards. Such criticisms concerned the allow-able
bearing stress on the pins, the lack of redundancy in
the structure, possible lateral movement of the hangers on
the pins due to out- of- plane distortions, and drainage system
problems. All of these issues were addressed at the hear-ings.
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None of the facts developed on the record point to
any inadequacies in the design under the standards prevail-ing
in 1954. The design and details used were proper and
were consistent with those standards. Neither the witnesses
nor the exhibits revealed any errors in the design calcula-tions.
The drainage system selected for the bridge was com-mon
to many of the bridges in Connecticut and other states.
Accordingly, the drainage problems which the Mianus River
Bridge has exhibited exist on many other bridges in Connec-ticut.
A. The Design For the Mianus River Bridge Was Prepared In
Accordance With Specifications and Alignments Supplied
By the State of Connecticut.
A predecessor of TAMS, Knappen- Tippetts- Abbett-
McCarthy (" Knappen"), designed the Mianus River Bridge in
1954 and 1955 pursuant to a contract negotiated with the
State of Connecticut. ( Gersten, Tr. 51, 52.) The design
was based upon criteria established at meetings with Con-necticut
officials and other engineers engaged by the State.
Specifically, other engineering firms working for the State
established the alignment for the highway then known as the
Greenwich Killingly Expressway, of which the Mianus River
Bridge is a portion. ( Gersten, Tr. 54- 57; Exh. VI- 5a, 5b.)
The skew of the Mianus River Bridge was determined by that
mandated alignment.
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The actual design was prepared by Knappen, which
also supervised and inspected the construction of the bridge.
The State Highway Department reviewed and approved the plans
and was aware of the design details. ( Gersten, Tr. 53, 54;
Gubala, Tr. 744, 745.) TAMS was also responsible for review
and approval of shop drawings. The State was responsible
for shop and mill inspection of steel and required materials
testing. ( Gersten, Tr. 65.)
No one now employed by TAMS or the State was in a
responsible position in the design of the Mianus River Bridge.
The employees or partners in responsible charge of the de-sign
of the bridge have left TAMS or its predecessor firms
and are retired or deceased. ( Gersten, Tr. 52.) Dr. Gubala,
chief transportation engineer of the Department of Trans-portation
of the State of Connecticut (" ConnDOT"), was un-able
to identify any of the ConnDOT employees or former
employees who were involved with the design and construction
of the Mianus River Bridge. ( Gubala, Tr. 695- 96.)
B. The Bridge Was Designed Consistent With Engineering
Theories and Techniques Prevalent In the 1950' s.
The Mianus River Bridge is a 24- span viaduct 2656
feet long. The span that collapsed was a 100- foot two- girder
span suspended from adjoining 45- foot cantilevers. The east
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end of the suspended span was supported by two pin- and- hanger
connections; the west end rested on fixed bearings. ( Gersten,
Tr. 59- 60; Exh. VI- 1.) The span that collapsed was one of
four identical suspended spans.
The bridge design was consistent with the stand-ards
accepted at the time of the execution of the design of
the bridge in 1954 and 1955. These standards included the
" Standard Specifications for Highway Bridges," AASHO,* Sixth
Edition, 1953 ( Exh. VI- 36; Gersten, Tr. 65); and the " Stand-ard
Specifications for Roads, Bridges, and Incidental Con-struction,"
Connecticut State Highway Department, January
1955 ( Exh. VI- 3). Information relating to the design was
furnished to TAMS's predecessor Knappen at meetings with the
State and other consulting engineers employed to design
other sections of the Expressway. ( Gersten, Tr. 54, 56, 61,
62, 90, 110.)
The design executed by Knappen was typical of
those of the period. ( Gubala, Tr. 689.) Mr. Sears, Chief
of the Review and Analysis Branch, Bridge Division, of the
FHWA, agreed that a two- girder system in the 1950' s would
have been an acceptable solution to spanning the channel.
AASHO, the American Association of State Highway Offi-cials,
was the predecessor of AASHTO, the American
Association of State Highway and Transportation Offi-cials.
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( Sears, Tr. 759.) Concerning the design type, Mr. Drugge
acknowledged that he might have designed the Mianus River
Bridge the same way given the knowledge and conditions that
existed in 1954. Indeed, Mr. Drugge pointed out that sim-ilar
non- redundant designs are built today. ( Drugge, Tr.
174- 75.)
While the section of the Mianus River Bridge that
collapsed was not redundant, this was not a design con-sideration
in the 1950' s. The concept of using redundant
structures was not established in any of the design codes as
a requirement in the 1950' s, at the time the Mianus River
Bridge was designed. Indeed, redundancy is not required
today. However, in the 1977 AASHTO Standard Specifications
for Bridges, there is a requirement for reducing the allow-able
range of stress in structures subject to repetitive
loadings. The reduction of stress applies to Non- Redundant
Load Path Structures and is defined by AASHTO ( p. 145) as
"[ s] tructure types with a single load path where a single
fracture can lead to catastrophic collapse." It is clear
that current design practice does not prohibit non- redundant
structures but only reduces the allowable range of s
Indeed, even Dr. Gubala acknowledged that redundancy was not
required on the Mianus River Bridge when he stated " I be-lieve
the designer used what was the state of the art at the
time." ( Gubala, Tr. 733.)
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C. The Pins Used In the Pin- and- Hanger Assemblies Support-ing
the Bridge Were Correctly Sized, Based on Allowable
Stresses That Were Correctly Selected.
The design of the pins in the pin- and- hanger as-sembly
was in accordance with the provisions of the 1953
AASHO specifications. The design was based upon the proper
truck loads and the correct allowable stresses, and employed
the methods of calculation prevalent at the time. There was
no evidence that established that the stresses or calcula-tions
were improper.
The truck loading used was the H- 20- S- 16 truck, as
provided by the AASHO specifications. ( Gersten, Tr. 65- 66;
Exh. VI- 36 at 162.) The allowable bearing stress used for
the design of the pins was 24,000 pounds per square inch
(" psi"). This allowable stress was also based on AASHO
standard stresses. ( Gersten, Tr. 66- 69; Exh. VI- 36 at 177.)
Texts current at that time indicated that such an
allowable stress was proper. Thus, Edward H. Gaylord, Jr.,
and Charles N. Gaylord, in their standard 1957 text, Design
of Steel Structures, specifically referred to suspended
cantilever spans as examples of pinned connections which
permit only small rotations and therefore have higher allow-able
bearing stresses. ( Gersten, Tr. 70; Exh. VI- 65 at
- 9-
485- 487.) Similarly, Grinter, in his Design of Modern Steel
Structures ( 1954), indicated that such a bearing stress was
proper. ( Gersten, Tr. 72- 73; Exh. VI- 62 at 309, 327.)
Mr. Cavanaugh, ConnDOT's Engineer of Bridges and
Structures in the Bureau of Highways, agreed that the 24,000
psi used in the design was allowed ( Exh. IV- 15), and Mr.
Sears of the FHWA stated that he would have approved the
use of 24,000 psi at the time of the design. ( Sears, Tr.
776.) The calculations showing the bearing stress value
used were supplied to the State. Even the State's witness,
Mr. Drugge, acknowledged that the design stress may have
been " common practice at the time" the bridge was designed.
( Drugge, Tr. 157.)
Moreover, the post- 1955 development of the AASHO
and AASHTO standards governing the allowable bearing stress
on such pins further indicates that 24,000 psi was the cor-rect
allowable stress for pins not subject to rotation when
the bridge was designed. The specifications were revised
only after 1964 to prescribe a lower allowable bearing
stress. ( Gersten, Tr. p. 73, 74, 75; Exh. VI- 61, 63, 64.)
AASHO's 1964 interim specification provided for an allowable
stress for pins " subject to rotation due only to expansion
or deflection" of 26,000 psi. ( Gersten, Tr. .73.) In 1965,
- 10-
this value was set at 29,000 psi for pins not subject to
rotation, but was reduced to 14,000 psi for pins subject to
rotation such as those in rockers and hinges. ( Gersten, Tr.
75; Exh. VI- 61 at 82.) Not until 1977 did AASHTO state that
the value for pins " not subject to rotation . . . shall not
apply to pins used in members having rotation caused by
expansion or deflection." ( Gersten, Tr. 75.)
This history shows a gradual clarification and
evolution in detail of the AASHTO standard. A comparison of
the first and last standards shows quite clearly, however,
that the meaning of the term " subject to rotation" changed.
At the start, that term, as applied to allowable stresses on
bearings, specifically excluded situations in which rotation
was due to expansion or deflection; by 1977, it explicitly
included rotation caused by expansion or deflection. Thus,
regardless of what the term " subject to rotation" may mean
today, those allowable bearing stresses were higher when the
Mianus River Bridge was built than they are now, and the de-sign
incorporated the proper value.
D. The Pin- and- Hanger Assembly and the Retaining Plate and
Bolt Configuration Were Correctly Selected In Accord-ance
With Contemporaneous Design Standards.
The type of detail for the retaining plate and
bolt was a common one and is shown in the American Institute
- 11-
of Steel Construction (" AISC") handbook. ( Gersten, Tr.
86- 87; Exh. VI- 4.) This detail has also been used in many
other bridges with suspended spans for pins of greater and
smaller diameter. ( Gersten, Tr. 87.)
Bridges supported by pin- and- hanger assemblies are
not inherently unstable; such bridges exist and remain in-tact
in other states. There are numerous bridges with pin-and-
hanger assemblies in New York, New Jersey and Massachu-setts,
as well as in many other states. ( Gersten, Tr. 57- 58.)
These include the New Jersey Turnpike Bridge over the Passaic
River, the Roslyn Viaduct in Long Island, and several on the
Whitestone and Van Wyck Expressways in New York City. ( Gersten
Tr. 62, 87, 91- 92.)
The American Road and Transportation Builders
Association ( ARTBA) recently surveyed all of the states
concerning suspended spans" following the collapse of the
span on the Mianus River Bridge. They received responses
from 49 states ( including Connecticut) and the District of
Columbia. The responses indicate that there are probably at
least 2,000 suspended spans in the United States. An over-whelming
majority of the suspended spans have tension links
and the remainder compression links. ( See letter dated
October 19, 1983, from ARTBA to state highway officials
previously submitted to the Board.)
- 12-
Recent articles indicate that there are about 31
such bridges in New York, 68 in Connecticut, and 54 in
Massachusetts. ( New Civil Engineer International, Aug.
1983.) In Michigan, there are 10 two- girder bridges and
1,132 multi- beam and girder bridges using pin- and- hanger
assemblies. ( Personal communication, State of Michigan
Office of the Design Engineer.) There are also analyses of
such bridges in published articles and books; at least 19 of
them are listed in Engineering News Record ( Jan. 17, 1952;
Apr. 10, 1958; Feb. 22, 1962), Civil Engineering ( May 1960;
Oct. 1962), Modern Welded Structures ( Vols. I, II and IV),
and other sources. Six other bridgescompleted between
1945 and 1966, received awards from the American Institute
of Steel Construction. ( Prize Bridges - 1945, 1954, 1957,
1959, 1963, 1966.)
E. The Collapse of the Mianus River Bridge Was Not Related
to Design and Most Probably Was Caused By Gradual,
Unchecked Corrosion and Forces Due to Ice Formation.
The bridge's deterioration over its 25- year life
was steady and unchecked. It was agreed by all of the ex-perts
who testified that this deterioration was a gradual
process rather than a sudden event. Moreover, no evidence
was presented which indicated that the failure was caused by
the allowable bearing stresses used in the design of the
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pin- and- hanger assembly. Rather, the movement of the hanger
off the pin was probably caused by forces related to cor-rosion
and/ or the formation of ice.
While one pin- and- hanger assembly collapsed, the
additional assemblies and other critical portions of the
bridge had suffered from varying but significant degrees of
deterioration. ( Drugge, Tr. 140.) Mr. Drugge specifically
testified that the concavity of the plate and distress
occurred " generally over the life of the bridge." ( Drugge,
Tr. 145.) Similarly, observations by Mr. Wakeland, an in-vestigator
with the NTSB, suggested deterioration over an
extended period of time. ( Wakeland, Tr. 210- 211.)
Dr. O'Rourke asserted that the degradation of the
bridge had probably started " three, four or five years after
the bridge was constructed, and proceeded at, depending
on . . . whether it was a rainy or snowy season, . . . a
more or less uniform rate until the time of the collapse."
( O'Rourke, Tr. 267.) Dr. O'Rourke examined and rejected the
hypothesis that the bridge stress occurred as a result of a
traumatic event, such as an extra heavy load, occurring
after the bridge inspection and just prior to the bridge's
collapse. ( O'Rourke, Tr. 267.)
- 14-
Significantly, Dr. O'Rourke stated that in his
opinion " the stress on that bridge would have been evident
to an inspector for three or four years before the actual
collapse." ( O'Rourke, Tr. 267.) In short, as discussed
below ( see infra pp. 27- 52), the deterioration of the bridge
could have been detected and arrested at any time prior to
the collapse.
Several plausible mechanisms of deterioration of
the Mianus River Bridge during the past 25 years were iden-tified
at the Board hearing. While the immediate causes of
the collapse are unclear, all witnesses acknowledged the
deterioration of the bridge's structure which clearly had
occurred. The principal factors postulated as having caused
this deterioration were ice and corrosion, possibly accel-erated
by the presence of salt and debris.
Corrosion ( i. e., rust) was certainly the most
evident form of deterioration. The earliest bridge safety
inspection report made available, that of the January 23,
1962, inspection, documents the rust build- up on the bridge.
( Exh. VI- 10.) Moreover, in every bridge safety inspection
conducted from January 24, 1975 through 1982, the State's .
bridge safety inspectors reported the build- up of rust in
- 15-
their inspection reports. ( Exh. VI- 10.) The presence of
rust at recent inspections was reported by both Charles
Everest and Jerry White, the bridge safety inspectors who
inspected the bridge in 1982. ( Everest, Tr. 538, 542- 43,
560, 571; White, Tr. 591, 592- 93, 609- 10; Exh. IV- 27, IV- 28.)
Moreover, corrosion was discussed by practically all of the
expert witnesses who testified at the hearing as one of the
possible major causes of the collapse of the bridge. ( Gersten,
Tr. 100; Drugge, Tr. 144- 45, 171- 72; Wakeland, Tr. 203;
O'Rourke, Tr. 252, 255, 270.) In fact, of the experts, only
Dr. Zetlin failed to postulate the causal effect of corrosion,
and even he admitted the pervasive presence of corrosion on
the bridge. ( Zetlin, Tr. 317- 18.)
The hearing witnesses also detailed the critical
impact of ice in the bridge structure's deterioration. Ice
can form around portions of the bridge such as the link
hangers. As the ice forms, it expands and creates pressures
on the structure. At the hearing, Dr. O'Rourke described
the significant effect which ice had in causing the deter-ioration
of the bridge's structure. In fact, while Dr.
O'Rourke believed that ice and rust acting in concert re-sulted
in the degradation of the critical pin- and- hanger
assembly, he stated that the pressure exerted by ice on its
- 16-
own would have been sufficient to push the hangers laterally
off the pin. ( O'Rourke, Tr. 254- 55, 270; see also Gersten,
Tr. 100.)
Salt was suggested as a corrosion- accelerating
agent in the structure's deterioration. ( See Drugge, Tr.
163.) The salt contacted the bridge structure by two means:
by reason of the bridge's close proximity to Long Island
Sound; and through the application of salt to the bridge
deck by ConnDOT during the winter for snow and ice control.
This road salt was never flushed and apparently remained on
the road surface or washed off the bridge, potentially con-tacting
the pin- and- hanger assemblies. ( LeFrancois, Exh.
IV- 13 at 2; Satagaj, Tr. 432.) Joseph Pastore, a ConnDOT
bridge maintenance inspector, stated that this resulted in
corrosion on the bridge. ( Pastore, Exh. IV- 17.)
All of the aforementioned deteriorating agents
occur in nature; thus, bridge inspectors must be wary of
them and must inspect the bridge to ensure that they do not
impair its structural integrity. In the instant situation,
the corrosive nature of these forces was likely exacerbated
by the drainage problems associated with the Mianus River
Bridge. These problems were brought out in detail at the
hearings and included paved- over drains, scuppers filled with
- 17-
debris, and missing troughs. All of these problems resulted
in an exce# s s flow of water and salt upon the critical and
sensitive elements of the bridge structure.
F. The Differences Among the Allowable Stress Used In the
Pin Design, as Originally Designed, the Actual Stress
In the Pin, and the Allowable Stress Which Would be
Required Using Current Design Standards, Did Not Con-tribute
to the Mechanism of the Accident.
The actual stresses in the pin due to design loads
were substantially less than the stresses allowed by the
1953 AASHO Design Specifications. Thus, although the allow-able
stress was 24,000 psi,' the actual bearing stress was
only 17,900 psi. The dead load stress was 11,900 psi.
( Gersten, Tr. 68, 69; Exh. VI- 36.) However, there is no in-dication
that there was a bearing failure in either the pins
or hangers. The mechanism of collapse was a movement of the
hangers laterally off the pin. ( Gersten, Tr. 99, 100, 101;
Drugge, Tr. 145, 146; O'Rourke, Tr. 230, 231, 232, 233.)
While current AASHTO specifications require a smaller bear-ing
stress on pins in this type of service than AASHO re-quired
in 1953, there was no failure relating to excessive
bearing stress. ( Gersten, Tr. 75.)
G. The Design Criticisms Offered By the State Are Fac-tually
Unsupported and Should be Disregarded.
The State has offered, through a variety of wit-nesses
and exhibits, several criticisms of the design of the
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Mianus River Bridge. These criticisms are not supported by
the record evidence and should, for the reasons discussed in
this section, be disregarded.
1. Out- of- Plane Distortions:
The role of out- of- plane distortions was empha-sized
by Dr. Zetlin. Alone among the expert witnesses who
testified, Dr. Zetlin stated his belief that the collapse
was due only to out- of- plane distortions resulting in lat-eral
forces on the hanger. These forces were postulated to
have pushed the hanger off the pin over a period of 15 to 20
years. ( Zetlin, Tr. 280, 328.)* Dr. Zetlin also stated
that the " collapse had occurred at the northeast corner"
( Zetlin, Tr. 307), not the southeast corner as others had
testified. Dr. Zetlin's theories remain speculative and are
computationally unsupported. His theory that the failure
occurred at the northeast corner is contradicted by the
physical evidence.
Dr. Zetlin made no calculations to establish the
magnitude of the out- of- plane distortions causing lateral
However, Dr. Zetlin agreed with the other witnesses
that rust had acted as a corrosive force on the bridge
( Zetlin, Tr. 318), and that whatever the cause of the
collapse was, it occurred over a long period of time
( Zetlin, Tr. 298, 328).
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forces, if in fact these forces existed. At the hearing,
Dr. Zetlin referred to little more than preliminary cal-culations
and " sheets of yellow paper," neither of which has
been produced. He stated that such calculations were dif-ferent
from the type of calculations usually done for pre-liminary
design. No numbers were available. ( Zetlin, 305,
326, 331- 332.) Since the hearing Dr. Zetlin has produced
several " Progress Reports" but no usable calculations. Dir.
O'Rourke, in his testimony, could not justify the hypothesis
that out- of- plane movements caused the collapse of the span.
( O'Rourke, Tr. 258- 261.)
Moreover, no evidence has been presented to sub-stantiate
Dr. Zetlin's observations that out- of- plane dis-tortions
due to the skew of the bridge caused movements
along the pin. Out- of- plane distortions occur in square
bridges as well as skew bridges and the rotations of the
floorbeams are comparable in value. ( Gersten, Tr. 98;
O'Rourke, Tr. 258- 261.)
Dr. Zetlin's belief that the collapse occurred at
the northeast corner is contrary to the testimony of others
and is not consistent with the physical evidence. The di-rection
of the bent fingers in the expansion joint is in-consistent
with the northeast corner's collapsing first.
- 20-
( Wakeland, Tr. 208- 10; O'Rourke, Tr. 245- 46.) The fascia
girder, which supported the outside of the span, had the
most damage, whereas the median girder was relatively un-damaged.
This indicates that the fascia girder impacted the
water and the river bottom first, which would have occurred
if the southeast corner had collapsed first. The southwest
fixed bearing was pulled off. ( Zetlin, Tr. 333.) This also
indicates that the southeast corner collapsed first.
In short, Dr. Zetlin's theories are unsupported by
observed facts, as yet unconfirmed by the metallurgical
tests he requires and expects to rely on, or verified by any
viable calculations. Indeed, Dr. Zetlin's theories are
inconsistent with the physical evidence. Even if the cal^
culations he proposes are possible today ( which remains
to be seen), they could not feasibly have been made in 1954
and 1955. Therefore, Dr. Zetlin's theories at their current
stage of articulation do not point to any deficiencies in
the design of the Mianus River Bridge or explain why it
collapsed.
2. Drainage:
Dr. Gubala stated that the drainage system was
" designed not to take the water that would flow down the
- 21-
gutterline totally, but to bypass much of it." The slope of
the drainage system was also criticized. ( Gubala, Tr. 691.)
The implication of these remarks was that the drainage was
designed incorrectly and that the scuppers should have picked
up all of the water.
In fact, the drainage system was properly de-signed.
It consisted of two basic components: scuppers
located along the curbs and copper troughs under the finger
joints. The purpose of the troughs was to catch any water
passing the roadway scuppers and to prevent that water from
dropping onto the pins and hangers. The trough on the span
that collapsed sloped from the southeast corner to the north-east
corner at a slope of 1.05 percent. Water would, there-fore,
be conducted to the downspout at the median and dis-charged
into the river.
f
Referring specifically to Dr. Gubala's criticisms,
it is not normal to design scuppers to pick up all water.
Scuppers are properly designed to limit the spread of water
on the roadway to a certain portion of the width of the
through- traffic lane. It is rarely practical to design
gutter sections to contain all of the run- off, even from
frequent rains. The design frequency and the inlet spacing
are selected so as to keep the spread of water on the trav-
- 22-
elled way within tolerable limits. ( See " Drainage of High-way
Pavements," Hydraulic Engineering Circular No. 12, dated
March 1969, prepared by the Hydraulics Branch, Bridge Divi-sion,
of the U. S. Bureau of Public Roads.) This reference
covers standard practice of drainage design and presents
basic criteria to follow during design.
In sum, the design of the drainage system is un-related
to structural design and consequently bears no causal
relationship to the collapse of the bridge. The record
demonstrates quite clearly that the drainage problems ex-perienced
were due to two causes: the failure to maintain
the drainage system and the paving- over of drains. In this
respect, the Mianus River Bridge was not different than
other bridges in Connecticut alluded to on the record.
( Supina, Tr. 453.)
3. ConnDOT " Internal Review" ( Exhibit VI- 43):
ConnDOT's " Internal Review" ( Exh. VI- 43) does not
contribute to an orderly evaluation of the bridge's design
or the causes of its collapse. However, since the report is
an exhibit, it is appropriate to highlight its inaccuracy on
these points. On pages 44 and 45 statements are made that
torsional forces and lateral forces due to the extreme skew
of the bridge " apparently were the main cause of the hanger
- 23-
slipping off the pin." These statements constitute a mis-characterization
of the testimony of Dr. Zetlin and Mr.
Drugge. No evidence was presented at the Hearing to justify
this conclusion. There were no calculations presented to
document this, and no metallurgical tests have been pre-sented
to identify the mode of failure.
4. S. T. Hudson Report ( Exhibit VI- 72):
Finally, nothing in the report apparently prepared
by a firm known as S. T. Hudson, International ( Exh. VI- 72),
contributes to an assessment of the bridge's design or col-lapse.
The nature of the report is unexplained. The ex-hibit
appears to be an excerpt from a larger report or
series of reports, since it starts on page 1 with Item 4 and
relates to the probable cause of failure. The rest of the
report is apparently missing. The purpose of the report is
nowhere explained. The qualifications of the authors are
not given. It is not clear whether the shortcomings which
are discussed concern engineering practice in 1983 or the
1950' s.
These uncertainties would have been cleared up if
it had been possible to cross- examine the authors of Exhibit
VI- 72. The specific comments on this exhibit will relate to
engineering practice when the bridge was designed in the
1950' s.
- 24-
The statements regarding lack of redundancy are
inaccurate. Bridges of similar design do not usually pro-vide
three or four girders. Non- redundant two girder bridges
were and are common. ( See O'Rourke, Tr. 251.) Many long
span bridges over waterways use either two girders, two
trusses, two suspension cables, or two arches, and as such
are non- redundant. Most single- track railroad bridges use
two girders or trusses and also are non- redundant. Most
pedestrian bridges use either two girders or two beams.
There are a number of two- girder bridges using pin assem-blies
in addition to the Mianus River Bridge. Included are
the Roslyn Viaduct in Long Island, the New Jersey Turnpike
Bridge over the Passaic River, the Calcasieu River Bridge
carrying 1- 210 in Louisiana, the Whiskey Creek Bridge in
California, and the Trinity River Bridge in Hoopa, California
The statement that "[ t] here was no built in safety
factor" ( Exh. VI- 72 at 1) is without foundation. The factor
of safety used in the design of the Mianus River Bridge
components was the same as that used in all bridge com-ponents.
The design used the proper allowable stresses and
therefore had the built- in safety factor required by the
AASHO code.
- 25-
Contrary to the statement that there was a rel-ative
lack of protection against corrosion ( Exh. VI- 72 at
1), no evidence was presented that engineers used stainless
steel on pin- and- hanger assemblies designed in the 1950' s.
In addition, AASHO specifications clearly allowed a variety
of steels to be used for pins in bridges, all related to the
strength of the material selected, not to its corrosion
resistance. Similarly, the pin selected for the Mianus
River Bridge met AASHO specifications and was comparable
with the pins used for other bridges having similar details.
- 26-
PART II
WITH A MORE EFFECTIVE ORGANIZATION, THE STATE
WOULD HAVE RECOGNIZED THE EXISTENCE OF PROBLEMS
AND WOULD HAVE DETECTED AND HALTED THE CORROSION
WHICH LED TO THE COLLAPSE OF THE MIANUS RIVER BRIDGE
The collapse of the Mianus River Bridge occurred
within the context of a national concern over bridge safety.
Nine years after the Mianus River Bridge was completed, the
Silver Bridge over the Ohio River at Point Pleasant, West
Virginia, collapsed. The disaster had two effects which are
relevant to this proceeding. First, as described by the
NTSB in its report on the collapse, the component of the
Silver Bridge which failed was similar to the pin- and- hanger
assembly on the Mianus River Bridge. Second, the collapse
stimulated the evolution and development of today's inten-sive
bridge inspection programs and legal requirements.
A. Effective Inspection Techniques Were Available to
Detect the Deterioration Which Ultimately Caused the
Collapse of the Mianus River Bridge.
1. Following the collapse of the Silver Bridge in
1967, the states knew that hard- to- inspect com-ponents
such as pin- and- hanger assemblies required
special inspection because they were essential to
a bridge's continued structural integrity.
On December 15, 1967, the Silver Bridge across the
Ohio River at Point Pleasant, West Virginia, collapsed,
- 27-
killing 46 people. This disaster and the governmental re-sponse
to it put every state on notice of the critical im-portance
of bridge inspections. More specifically, the
State was put on notice of the importance of inspecting such
critical but hard- to- inspect assemblies as the pin- and-hanger
bearings on the Mianus River Bridge.
The NTSB investigated the collapse and issued two
reports exploring in detail the causes of that collapse.
NTSB, Collapse of U. S. 35 Highway Bridge, Point Pleasant,
West Virginia, December 15> 1967, Case No. SS- H- 2 ( October
4, 1968 (" Interim Report") and December 16, 1970 (" Final Re-port")).
The NTSB determined that the collapse was caused
by the failure of a difficult- to- inspect eyebar in the eye-bar
chain which supported the suspension span. The NTSB
identified seven design trends, " each of which was common in
engineering practice in the era in which [ the Silver Bridge]
was designed," which contributed to the failure. ( Final
Report at 122.) The report, which was distributed to the
states, highlighted the importance of inspecting bridges
which reflected similar design trends.
The Mianus River Bridge was similar in several
respects ( see Final Report at 122- 23), not the least of
which was the similarity between the pin- and- hanger detail
- 28-
on the Mianus River Bridge and the eyebar joint on the Silver
Bridge. Thus, from the NTSB's reports alone, Connecticut
had reason to be cognizant of the need to subject the pin-and-
hanger assemblies to searching scrutiny.
However, the NTSB's reports did not exist in a
vacuum. There were, in fact, related events which should
have further heightened Connecticut's sensitivity to the
need to inspect the Mianus River Bridge. On March 12, 1968,
the FHWA distributed to the states " An Informational Guide
for Inspection of Highway Bridges," which had been prepared
in cooperation with AASHO.* This Guide, which predated the
legal requirements which now apply to bridge inspections,
opened with a reference to the Silver Bridge collapse, and
stated:
It is advisable that all official public
agencies that construct, operate and maintain
highway facilities take special action now to
again reevaluate the capability of bridges
and related facilities to continue to accom-modate
highway traffic and to take other
precautionary measures to reassure that other
such facilities will not fail under active
service.
This Guide was also marked as Exhibit 3U in the NTSB's
investigation of the Silver Bridge collapse. Since it
was. also distributed to the States, it is reasonable
for the Board now to take administrative notice of it.
- 29-
Each state was " expected to make further review of the ade-quacy
of the bridges" under its jurisdiction. A priority
list spelling out the order for conducting inspections
listed as the second priority " [ structures whose ability to
function properly depends on the ability of the pins or
joints to rotate and translate properly." The seventh pri-ority
was for "[ structures or routes where deicing chem-icals
are used liberally." Special attention during in-spections
was directed to bearings and expansion joints.
Thus, as early as 1968, the States had clear no-tice
of the importance of inspecting pin- and- hanger assem-blies
such as those found on the Mianus River Bridge. In
the specific case of the Mianus River Bridge, Connecticut
should also have recognized that the bridge had several
features which made it essential that the bridge receive
careful inspection. Moreover, by that time, the bridge had
been inspected at least five times. ( See Exh. VI- 10.) The
inspection reports consistently indicated that drains were
not being cleaned, which should have further alerted the
State to inspect the bridge carefully.
2. The numerous inspection manuals and guides that
were developed following the collapse of the Silver
Bridge highlighted the importance of detecting the
problems which contributed to the collapse of the
Mianus River Bridge.
The collapse in 1967 of the Silver Bridge over the
Ohio River at Point Pleasant, West Virginia, focused atten-
- 30-
tion on the necessity for regular programs of bridge safety
inspection. In response to the collapse, and partly as a .
result of the two reports on the collapse prepared by the
NTSB, the federal government began to promulgate regulations
prescribing minimum budget safety inspection requirements.
At the same time, AASHO, which had published a highway in-spection
manual in 1964,* prior to the Silver Bridge col-lapse,
continued to revise and reissue its bridge safety
inspection and related manuals to include new information.
Although these early manuals have now been sup-plemented
by later editions, the evolution of the manuals
illustrates the range, quality, and detail of information
that was made available to the states as long ago as 1964,
and which was available for their use in developing bridge
inspection programs. The steady growth in the number and
complexity of these manuals reflects a learning process.
Each subsequent manual built upon its predecessors; those
earlier editions were not retracted, and their instructions
were not to be discarded. Rather, the amount of information
which was available to organizations such as ConnDOT grew
steadily over time.
Indeed, this manual, entitled " Guide for Maintenance
Inspections," was included as Exhibit 3M in the record
of the NTSB's investigation of the Silver Bridge col-lapse.
- 31-
Thus, the 1964 AASHO Guide for Maintenance Inspec-tions
stated unequivocally ( at p. 27) that bridge inspec-tions
must be thorough: " Inspections should be complete in
essential detail and in no case should difficulty of access
to any part or any member be permitted to interfere with
thorough inspection." This did not change with time. No
subsequent manual retracted this instruction. Thus, as
early as 1964, Connecticut was on notice that all parts of
its bridges were to be inspected regardless of ease of ac-cess.
The importance of this warning was underscored by the
NTSB's two highly detailed reports on the collapse of the
Silver Bridge and their findings regarding the inspectabil-ity
of the components whose failure precipitated the col-lapse.
The proper conduct of bridge safety inspections is
described in manuals and guides that are readily available
from the FHWA or AASHTO. ( Kjellson, Tr. 511.) Federal
regulations require the state to comply with these manuals,
in particular the Training Manual and the AASHTO Manual
( Exhs. VI- 15, VI- 20), in carrying out their bridge safety
inspections. ( Ahlskog, Tr. 799- 800, 811, 816- 18; Exh. VI- 31.
The manuals clearly emphasize the importance of inspecting
pin- and- hanger assemblies on cantilever bridges, as well as
- 32-
the related expansion joints and drainage systems. ( Exh.
VI- 15 at 5- 62, 5- 71 to 5- 73, 5- 80 to 5- 81; Exh. VI- 20 at
8- 9.) None of the recommended inspections are described as
being intended to ferret out a single mechanism of failure.
Rather, they are intended to identify any form of distress
in these critical assemblies.
In addition, as discussed in this section, the
bridge inspection manuals and training guides provide un-ambiguous
directions to inspect pin- and- hanger assemblies.
These directions were specifically aimed at the type of
pin- and- hanger assemblies found on the Mianus River Bridge.
The directions did not limit the required inspection to any
specific potential bridge failure mechanism. Rather, any of
the potential mechanisms of failure identified in this pro-ceeding
were to be scrutinized in a properly conducted in-spection
carried out pursuant to these manuals.
Four generally applicable bridge safety inspection
guides and manuals were identified on the record in this
proceeding. These were:
i) Exhibit VI- 15: " Bridge Inspector's
Training Manual 70," published in
1970 and revised in 1979 by the
Federal Highway Administration of
the U. S. Department of Transporta-tion
( referred to as the " Training
Manual");
- 33-
ii) Exhibit VI- 17: " Bridge Inspector
Training Course: Inspection Check-lists"
.
iii) Exhibit VI- 18: " AASHTO Manual for
Bridge Maintenance - 1976," pub-lished
by AASHTO in 1976.
iv) Exhibit VI- 20: " Manual for Main-tenance
Inspection of Bridges,"
revised in 1982 by AASHTO ( referred
to as the " AASHTO Manual").
The inspection manuals articulate a series of pro-cedures
that would have enabled Connecticut to identify
potential failure mechanisms before they could have caused a
collapse. Some of these requirements are general in nature;
others apply directly to specific aspects of the Mianus
River Bridge.
The principal reference is the Bridge Inspector's
Training Manual. ( Exh. VI- 15.) As supplemented by the
Inspection Checklists ( Exh. VI- 17), the Training Manual is
the basic teaching resource for bridge inspectors in Con-necticut
as well as the federal government. ( Thomas, Tr.
624- 25; Cavanaugh, Tr. 655- 56; Ahlskog, Tr. 801- 02.) It is
lavishly illustrated and highly detailed. All Connecticut
bridge safety inspectors had taken the ConnDOT Bridge Safety
Inspections Division's training course at least once. ( Cav-anaugh,
Tr. 656.) All were familiar with the Training Man-ual.
( Everest, Tr. 543; White, Tr. 586.) Indeed, they used
- 34-
it as a reference resource and kept it in their truck.
( Everest, Tr. 544.)
The general provisions of the Training Manual
relate to the planning and thoroughness of the inspec-tion.
In planning an inspection, the inspector is directed
to review all available materials, including plans and pre-vious
inspection reports. ( Exh. VI- 15 at 3- 2.) Such a
review would have identified the critical members of the
Mianus River Bridge and would have alerted the inspector to
previously identified problem areas. The Manual stated that
the inspection should be thorough, with particular attention
focused on "[ s] tructurally important members" and "[ m] embers
most susceptible to deterioration or damage." ( Exh. VI- 15
at 4- 1.) If this step had been coordinated with a review of
plans and prior inspection reports, attention would have
been directed to the pin- and- hanger assemblies.
In addition, the Training Manual clearly states
that dirt and debris must be removed if necessary " to permit
precise measurement:"
Pre- inspection Cleaning. It will often be
necessary to remove dust, - debris, rust, paint
scale, or animal wastes before inspecting a
bridge member. Scrapers, wire brushes, air
jets, or shot blasting are very useful for
this purpose. A clean surface is partic-ularly
important when electronic devices are
used for inspection of steel or concrete.
- 35-
( Exh. VI- 15 at 4- 4.) Visual inspection must be supplemented
with special techniques where necessary. ( Exh. VI- 15 at
4- 1.) At the least, these requirements indicate that the
Mianus River Bridge should have been cleaned if the presence
of debris or pigeon droppings impeded inspection, which,
indeed, it did.* ( Exh. VI- 43 at 58.)
The Training Manual identifies eleven factors
which can cause deterioration of steel members. Among these
are air and moisture, " especially in a marine climate," de-icing
agents, and animal wastes. ( Exh. VI— 15 at 5— 8.) Given
the location of the Mianus River Bridge close to Long Island
Sound, the long- term use of deicers on the bridge ( Satagaj,
Tr. 436), and the acknowledged presence of animal wastes on
the bridge ( Exh. VI- 43 at 58), each of these factors should
have been especially important to an inspector examining the
Mianus River Bridge.
With regard to specific aspects of the bridge
structure, inspectors of main supporting members are di-rected
to be " particularly thorough" because " their failure
could cause the collapse of the bridge." ( Exh. VI- 15 at
In fact, however, the State had not had' a blaster for
cleaning such components for at least ten years. ( Exh.
IV- 16.)
- 36-
4- 2.) Among the members specified for such inspection are
main girders and hangers. The inspector is directed to look
for corrosion, connection slippage, and deformation due to
overload. ( Exh. VI- 15 at 4- 4.)
Particular attention is directed repeatedly to
pin- and- hanger assemblies that are critical to the support
of the bridge:
Where the main load of the bridge is carried
by a single member or element whose failure
would result in the collapse of the struc-ture,
the member should be inspected very
thoroughly for cracks and flaws either by
visual inspection or by a non- destructive
technique, such as ultrasonics or radio-graphy.
The pins and the hangers on the
suspended span of a two- girder cantilever
bridge, or the pins in a pin- connected truss,
are typical examples of such members.
( Exh. VI- 15 at 4- 4 ( emphasis added).) The inspector is
specifically directed to examine cantilever pin- and- hanger
expansion devices ( Exh. VI- 15 at 5- 41, 5- 62) to ensure that
they are functioning properly, that they are free of cor-rosion
and debris ( Exh. VI- 15 at 5- 60), and that rust accum-ulation
has not impaired the function of the assem-bly
( Exh. VI- 15 at 5- 43). In addition, the inspector is
directed to inspect areas " that may be exposed to roadway
drainage," and
[ a] t any point where two plates are in face
to face contact and water can enter ( such as
between a cover plate and a flange). If
- 37-
rusting occurs at this interface, the ex-pansive
force created will be great enough to
spread the plates.
( Exh. VI- 15 at 5- 42.) The pin- and- hanger assemblies on the
Mianus River Bridge were exposed to roadway drainage and
included several such face- to- face plates; a pre- inspection
review of the bridge's plans would have revealed this ex-posure.
The Training Manual focuses attention on expansion
joints and drainage. The inspector is directed to check
clearances within the joints and to see that joints and
drains are free of debris. ( Exh. VI- 15 at 5- 72, 5- 81.) In
addition, the bottom of the joint must be inspected " re-gardless
of accessibility." ( Exh. VI- 15 at 5- 73.) Drainage
at the expansion joint requires similar attention:
The gutters under expansion dams fill up very
rapidly, especially where roads are heavily sanded
in winter. This causes the storm water to over-flow
onto the bearings, end diaphragms, pier caps,
and bridge seats, resulting in severe rusting of
the steel and deterioration of the concrete. Of
special consequence is the deterioration and
freezing of expansion bearings and rollers.
( Exh. VI- 15 at 5- 81.)
The AASHTO Manual for Bridge Maintenance contained
a pointed discussion of the problems associated with pin-
- 38-
and- hanger assemblies.* This should have served as a " red
flag," alerting the supervisory personnel to the need to
direct the bridge safety inspectors to scrutinize the pin-and-
hanger assemblies:
Pin- and- Hanger Bearings:...
1. Problem
Rusting between the plates is very dif-ficult
to detect unless bearing is dis-mantled.
2. Prevention
Prevention is impossible since we cannot
paint between plates. Proper design is
the only solution.
If joints get clogged, it in fact fixes
the span. The joints must be kept cleaned
if failure is to be prevented.
( Exh. VI- 18 at 182.) This discussion should have alerted
the supervisor to the need for constant vigilance at all
pin- and- hanger assemblies. Moreover, it should be noted
that this manual was published in 1976; Connecticut received
this warning seven years before the collapse of the Mianus
River Bridge.
Although the AASHTO Maintenance Manual is directed
primarily to describing the maintenance procedures
normally used to correct frequently encountered prob-lems
of bridge repair, its discussion of these problems
provides an additional source of information to the
engineers responsible for bridge safety inspections.
Thus, its extensive discussion of problems associated
with drainage, expansion joints, and bearing systems
( Exh. VI- 18 at 63- 66, 89- 95, 171- 182) should have
alerted a supervisor to the need to inspect these areas
with particular care.
- 39-
B. ConnDOT's Organizational Problems Prevented Effective
Application of Available Inspection Techniques.
The record in this proceeding contains numerous
internal documents prepared by the State of Connecticut and
relating to bridge inspections. Like the manuals discussed
in the previous section, these documents establish inspec-tion
procedures that would have directed attention to the
pin- and- hanger assemblies on the Mianus River Bridge and
enabled the State to detect and arrest their deterioration
before it led to the bridge's collapse.
1. ConnDOT had prepared guides for its own internal
inspection requirements which specifically in-corporated
the generally applicable bridge in-spection
manuals.
Of the inspection manuals introduced as exhibits,
the principal manuals are Exhibits VI- 15 and VI- 20. Al-though
neither volume was promulgated by the State of Con-necticut,
both are applicable to it. Federal regulations
require all states to comply with the Training Manual and
the AASHTO Manual. ( Ahlskog, Tr. 799- 800, 810- 11, 816- 18,
820, 825; Exh. VI- 31.) In addition, the State's own in-ternal
memoranda ( Exh. VI- 12a) incorporate the following
materials into the State's " Procedural Manual":
By reference, the following publications are
made a part of this Manual:
- 40-
National Bridge Inspection Standards
Manual for Maintenance Inspection of
Bridges, AASHTO - 1974
Bridge Inspectors Training Manual 70 -
Federal Highway Administration
Recording & Coding Guide for the Struc-ture
Inventory and Appraisal of the
Nation's Bridges - July 1972
In addition, ConnDOT inspectors had taken the federal bridge
inspector's training course and could therefore have been
expected to be familiar at least with the Training Manual.
( Thomas, Tr. 624- 26; Cavanaugh, Tr. 657, 662, 676.) Fur-ther,
the State's Field Inspection Booklet ( Exh. VI- 16)
reprints several provisions of the Training Manual and the
AASHTO Manual. ( Exh. VI- 16.) The State's " Internal Review"
( Exh. VI- 43) acknowledges that the federal standards apply.
( Exh. VI- 43 at 18.) The Board should note, finally, that
one of ConnDOT's bridge inspectors acknowledged that non-federal
aid bridges are subject to the same inspection
standards and procedures as federal aid bridges. ( Everest,
Tr. 557.)
The Inspection Booklet summarizes the requirements
spelled out in greater detail in the Training Manual and the
AASHTO Manual. It specifically directs the inspector's
attention to i) " cantilever hanger- and- pin connections,"
- 41-
ii) areas under joints and " at any other points that may be
exposed to roadway drainage," and iii) face- to- face plates.
( Exh. VI- 16 at 8.) Cleanliness, " especially on the top side
of the bottom flange," must be checked ( Exh. VI- 16 at 8), as
must the functioning of hangers on cantilevered bridges
( Exh. VI- 16 at 10).
Finally, several internal memoranda prepared by
ConnDOT officials were circulated to call attention to spe-cific
aspects of state bridge safety inspections. These
memoranda were sent to all bridge safety inspectors, and
dealt with the importance of inspecting bridge bearings and
joints ( Exh. VI- 12c, 12f); proper use of the snooper ( Exh.
VI- 12e); and the need ± o inspect skewed bridges because of
the possible effects of out- of- plane movements ( Exh. VI- 12d).
2. If ConnDOT had followed its own established pro-cedures,
it could have responded to the visible
effects of corrosion.
a. The progress and results of each of the iden-tified
mechanisms of deterioration were de-tectable
through thorough routine inspection
techniques.
Various witnesses testified that the effects of
deterioration were in fact visible. Several expert wit-nesses
testified about their inspection of the Mianus River
Bridge after the collapse. Their testimony demonstrates
- 42-
that several indications of deterioration or distress should
have been readily apparent to a properly trained and equipped
inspector. In addition, the testimony and actions of these
experts also indicate that visual inspections alone were
inadequate and that application of more specialized in-spection
techniques immediately revealed the degree of .
deterioration on the remaining spans.
On the day after the collapse, runoff was observed
to be falling through the expansion joints instead of the
drains and was observed to have left dark stains on the
beams below. ( Wakeland, Tr. 203.) The other intact spans
were, to varying degrees, measurably lower than the adjacent
spans. ( Wakeland, Tr 206, 212.) The finger joints of the
expansion joint of the fallen span were observed to have
been in contact. ( Wakeland, Tr. 208.) These conditions
were readily apparent, and should have been evident to a
safety inspector as signs of a potential problem. ( Wake-land,
Tr. 210, 215; Drugge, Tr. 148.) More importantly, it
is extremely unlikely that they were present when the Mianus
River Bridge was built. ( Wakeland, Tr. 216.)
Deterioration of the pin- and- hanger assemblies was
also clearly visible. Rusting or freezing of the assemblies
was noted five times in the inspection reports from 1975 to
- 43-
1982. ( Exh. VI- 10.) According to Dr. Zetlin, " it was easy
to observe corrosion." ( Zetlin, Tr. 318.) Rust would have
been clearly visible from the snooper, or even through bi-noculars
from the ground. ( Drugge, Tr. 179, 183.) The
presence of rust " certainly" would have caused the inspector
to go out and look at the pin- and- hanger assembly in detail.
( Drugge, Tr. 156.) At the least, he would have notified his
superiors " that perhaps the condition was serious and needed
further investigation." ( Drugge, Tr. 156.) The deformation
(" dishing") of the retainer plate was clearly visible from
" more than six feet away." ( O'Rourke, Tr. 237.) It was
visible from the snooper.* ( Drugge, Tr. 145.) The distance
between the girder webs and the hanger of the fallen span
was measured and shown to be twice the distance indicated on
the plans. ( O'Rourke, Tr. 241, 255.) This distance would
have been " easily" measurable ( O'Rourke, Tr. 251; Drugge,
Tr. 141, 153), which would permit anyone with access to the
plans to determine the amount of bearing surface. ( Drugge,
Significantly, ConnDOT, in its " Internal Review" ac-knowledges
that the outer pin and hanger assembly would
have been fully inspectable if the snooper had in fact
been used. Both outer pins and the lower inside pin
were inspectable from the snooper ( Exh. VI- 43 at 39,
42). The upper inside pin was inspectable at close
range from the floorbeams ( Exh. VI- 43 at 42), as it in
fact was during the September 1982 inspection.
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Tr. 141.) In short, " the stress on the bridge would have
been evident to an inspector for three or four years before
the actual collapse." ( O'Rourke, Tr. 267.)
These readily visible conditions strongly indi-cated
a need to pursue more detailed examinations, as sug-gested
by the Training Manual. ( Exh. VI- 15 at 4- 1.) Such
steps, which included drilling through and then removing the
retainer plates, immediately indicated the nature and ad-vanced
degree of the deterioration which had occurred.
( Drugge, Tr. 141, 146.)
Moreover, even if the State had not been inspect-ing
the Mianus River Bridge regularly, it was certainly on
notice that there were significant problems associated with
the Bridge. As developed in an independent investigation
conducted by the Connecticut State Police, the record is re-plete
with evidence of public complaints or inquiries about
noises and structural problems. See " An Investigation into
the State Department of Transportation's Processing of Com-plaints
Concerning the Mianus River Bridge," Conn. State
Police Case No. G83- 259200 ( the " Police Report"). Moreover,
the report prepared by the Connecticut State Police doc-uments
numerous other complaints which were lodged with
ConnDOT.
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As described in the Police Report, the volume and
frequency of complaints from the disinterested public, is
significant for two reasons. First, the fact that the pub-lic
could perceive problems highlights the degree to which
those problems should have been apparent to the State's
trained observers. Second, it was incumbent upon the State
to act decisively to determine the basis for the persistence
of these complaints.
b. ConnDOT's organizational structure did not
facilitate the implementation of an effective
program of integrated inspection and main-tenance.
ConnDOT seemingly was not organized in a manner
which facilitated making proper observations or transmitting
reports to persons who would understand their seriousness.
Many of these problems were detailed in the State's own
report on the bridge collapse. Others were detailed at
length in the testimony.
Inspection of the bridge was split between two en-tirely
distinct and separate units: the bridge safety in-spection
unit and the bridge maintenance inspection unit.
( Supina, Tr. 447- 48.) Various persons actually involved in
the hands- on work of these units suggested that this organ-izational
structure was not productive. ( LeFrancois, Exh.
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IV- 13; Thomas, Exh. IV- 14.) In fact, Mr. LeFrancois asserted
that'combining the two units would improve and expedite the
maintenance of critical systems. ( LeFrancois, Exh. IV- 13.)
Aside from this, however, it appears that there was very
little coordination and communication between the two de-partments.
( Thomas, Tr. 632, 650- 51; Cavanaugh, Tr. 661;
Gubala, Tr. 734- 35.) As the State's " Internal Review" ac-knowledged,
the bridge safety and bridge maintenance in-spectors
exchange neither inspection reports nor inspection
schedules. ( Exh. VI- 43 at 15.) Clearly, while bridge main-tenance
inspectors were not trained in bridge safety inspec-tion
( they had little training other than on- the- job training
from co- workers with presumably no formal training; Supina,
Tr. 446), the observations contained in their reports might
have indicated to others who were better trained that the
bridge had serious structural problems ( see Supina, Tr.
450). For example, various maintenance inspectors testified
that they knew about the clogged drains, paved- over scuppers
and corrosion well prior to the bridge collapse. ( Hemingway,
Tr. 363; LeBlanc, Tr. 374; Hemingway, Exh. IV- 12; LeFrancois,
Exh. IV- 13; LeBlanc, Exh. IV- 16.) However, the bridge safety
inspectors never saw these reports; and as Dr. Gubala pointed
out, they were never reviewed by a professional engineer
( Gubala, Exh. IV- 19).
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On the other hand, the bridge safety inspectors
did not even seem to consider requesting maintenance, pre-ventive
or otherwise, to maintain the integrity of the
bridge's structure. All requests for maintenance from
bridge safety inspectors were supposed to be transmitted
from Mr. Cavanaugh's office to Mr. Supina's office. ( Supina,
Tr. 448- 449, 457- 460, 466- 467.) Nevertheless, despite the
admitted problems with some of Connecticut's bridges, Mr.
Supina never saw the bridge safety inspector's reports and
received only five to ten requests for maintenance each year
from Mr. Cavanaugh. ( Supina, Tr. 457; Supina, Exh. IV- 18.)
There were other apparent communication problems
within the two individual sections. For example, Mr. Crucitti
stated that he was involved in the paving- over of the scup-pers
in the early to mid- 1970' s. He assumed that these
scuppers were being covered to protect them while certain
contracting work was being performed. He believed that the
scuppers would be uncovered once the contracting work was
over. ( Crucitti, Tr. 390- 392, 406.) In fact, these scuppers
were not uncovered, despite the fact that this condition was
consistently listed on the inspection or maintenance re-ports.
Finally, in March 1983, Mr. LeFrancois advised his
superior, Mr. Smith, of the situation. ( LeFrancois, Tr.
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410- 411, 432.) Somewhere along the line, however, the line
of communication was broken because Mr. Satagaj, Mr. Smith's
superior, stated that he did not know about this condition
until the bridge collapsed. ( Satagaj, Tr. 426.) Mr. Supina
stated that he would never pave over a drain ( Supina, Tr.
452- 453; see Supina, Tr. 467- 468); however, Mr. LeFrancois,
who stated he had authority to uncover the drains ( LeFrancois,
Tr. 422), did not do so because he was waiting for orders
from his superiors ( LeFrancois, Tr. 410- 411).
There also were communication problems involving
the bridge safety inspectors. Mr. White testified that on
four or five occasions he advised his superiors about the
dangerous conditions on the Mianus River Bridge, but there
is no evidence of any changes having been effected. ( White,
Tr. 591.) Similarly, none of Mr. White's superiors ever
noted or acted upon the fact that the report of the Sep-tember
1982 inspection contained no field notes. ( White,
Tr. 615- 616.)
Additionally, problems may have occurred because
both the bridge safety and bridge maintenance inspectors had
little formal training and had not read many of the AASHTO
materials. Mr. Everest stated that they never took measure-ments,
never requested the bridge plans prior to the in-
spections ( Everest, Exh. IV- 27), and had never been in-structed
on how to inspect pin- and- hanger assemblies.
Another state agency, the Connecticut State Police
Department, has also investigated the incident; its report
discusses another coordination difficulty within the ConnDOT
system. Dr. Gubala described in his interview ConnDOT's
system for handling and processing complaints. ( Gubala,
Exh. IV- 19.) Unfortunately, the State Police determined
that this system did not function properly as regards the
Mianus River Bridge. Most complaints were made to ConnDOT
by telephone; yet the State Police concluded that at least
six confirmed phone calls, and perhaps many more, in which
complaints were registered as to conditions on the Mianus
River Bridge, were lost as a result of ConnDOT's " informal
process" of handling complaints. Additionally, ConnDOT
District # 3 violated its own procedures and had no records
of any complaints. Moreover, more complaints might have
been called into ConnDOT except that the " complaint phone"
at the Greenwich ConnDOT garage was often unmanned. ( Police
Report, p. A34.)
Most critically, none of the management personnel,
bridge maintainers, or bridge inspectors had any knowledge
of the complaints filed other than the ones with which they
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were personally involved. Of the 17 callers to the ConnDOT
who said they had reached a clerk and were able to file a
complaint, 10 complained about noise and vibration problems
on the bridge. ( Police Report, p. A34.)
Had ConnDOT engineers been aware of this high
volume of complaints, perhaps they would have known that
there was a serious structural problem on the Mianus River
Bridge, particularly in light of the graphic nature of the
complaints made to ConnDOT ( see, e. g., Police Report, pp.
B13, B33). The State Police report also detailed the con-fusion
and lack of a coherent state policy regarding over-weight
vehicles on the bridge. ( Police Report, p. A33.)
ConnDOT" s inspection efforts were greatly hampered
by a lack of funding. This funding limitation would have
rendered proper inspection difficult with the best of organ-izations.
Perhaps the strongest evidence of this situation
was that ConnDOT's only snooper was out of service as of
August 1982 and thus was not available for use in the Sep-tember
1982 safety inspection of the Mianus River Bridge.
( Exhs. IV- 12, IV- 14.) This was particularly critical, as
the Mianus River Bridge was one of 162 bridges in Connec-ticut
for which a snooper was required for proper inspec-
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tion. ( Exh. VI- 43 at 48.) Specifically, the snooper was
needed to inspect many of the pin- and- hanger assemblies on
this bridge. Originally, ConnDOT was scheduled to have four
snoopers but due to funding problems had only one, and that
had been removed from service.
Furthermore, the tools and equipment available to
maintenance and safety inspectors were inadequate and had
been dwindling over the years. These included limited equip-ment
for critical maintenance and inspection ( e. g., scaf-folding
and usable catwalks). ( LeBlanc, Tr. 378, 380, 384,
386; Crucitti, Tr. 398, 405; Exhs. IV- 16, IV- 26.) Moreover,
when the State did recognize that repairs were needed, they
were often delayed due to funding problems. ( See, e. g.,
Police Report, p. B39.)
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PART III
RECOMMENDATIONS
A. Accident Investigations
1. The National Transportation Safety Board
should be empowered, as it is in the investigation of air-craft
accidents ( see 49 U. S. C. § 1441( c), ( d)), to take pos-session
of all physical evidence and to conduct, or arrange
for the conduct of, all necessary and appropriate tests.
B. Inspection and Design
1. States should require their consulting en-gineers
or engineering departments, on plans for bridges, to
call attention to details difficult to inspect or maintain.
2. States should instruct their consulting en-gineers
or engineering departments to identify and list
fracture- critical members or to place references identifying
the locations of such members on the bridge plans to aid
inspectors in identifying them.
C. Conduct of Inspections
1. All safety inspections should be performed or
monitored by engineers experienced in either design, in-spection
or construction of bridges. This will assure that
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inspectors will have an understanding of the function of
special details and will recognize any problems at a suffi-ciently
early stage.
2. Inspection teams should be supplied with
structural plans before and during the performance of in-spections.
The plans should include not only the General
Plan and Elevation drawings but also drawings of unusual
details. This preparation will enable the inspectors to
make measurements, where appropriate, and to obtain suf-ficient
information to permit the results of the measure-ments
to be interpreted by others.
3. The inspection reporting form to be prepared
by the inspectors should provide for sufficiently specific
recording of the observations made by the inspectors. For
example, the reporting form should provide for the recording
of observations of each element in each span superstructure
and each pier instead of merely the rating of the bridge as
a whole. This will enable the inspector to- document the
specific problems in each span. The form should also have
sufficient space for remarks where appropriate. A copy of
the form used in New York State is attached as an example of
how such an inspection form might be structured.
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4. Inspection teams should be informed of the
results of their inspections, i. e., whether corrective mea-sures
were taken after problems were pointed out.
D- Organization of Inspection
1. Major bridges should be inspected period-ically,
for example at five- or ten- year intervals, by in-dependent
outside consultants as is now done with dams sub-ject
to the regulatory jurisdiction of the Federal Energy
Regulatory Commission. ( See 18 C. F. R. Part 12.)
2. Independent outside consultants should be
retained to review state inspection procedures and equipment
requirements periodically, perhaps every five years.
CONCLUSION
This proceeding was convened to assist the NTSB in
determining the probable cause of the collapse of the Mianus
River Bridge on June 28, 1983, and to propound recommenda-tions
for preventing similar accidents in the future. TAMS
respectfully submits that the evidence gathered at the hear-ings
or included in the record since then establishes that
the bridge was properly designed and that the bridge's col-lapse
was caused by gradual deteriorative phenomena during
its lifetime. These phenomena and their e f f 6 C t S were not
detected through appropriate and available inspection tech-niques,
and responsive maintenance did not occur. The rec-ommendations
presented above are intended to enable the NTSB
to establish constructive procedures which will tend to
prevent a recurrence of the tragedy that occasioned this
proceeding.
Respectfully submitted,
TIPPETTS- ABBETT- McCARTHY- STRATTON
Partner
Dated: December 19, 1983
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