NTSB Determines Poor Planning and Inadequate Bracing Caused Girder Collapse

[NTSB Press Releases <NTSBPressReleases@xxxxxxxx>]

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                      NTSB PRESS RELEASE
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National Transportation Safety Board
Washington, DC 20594

FOR IMMEDIATE RELEASE: May 31, 2006
SB-06-33

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NTSB DETERMINES POOR PLANNING AND INADEQUATE BRACING
CAUSED DEADLY HIGHWAY BRIDGE GIRDER COLLAPSE

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Washington, D.C. -- In a report adopted today, the National 
Transportation Safety Board determined that poor 
construction planning and execution led to the failure of a 
temporary bracing system for a bridge girder being installed 
above Interstate 70 (I-70) in Golden, Colorado, causing the 
girder to collapse onto a passenger vehicle on I-70, killing 
three people.  The Board cited as contributing factors the 
lack of uniform, consistent bracing standards and the 
Colorado Department of Transportation's (CDOT's) narrow 
definition of falsework, which did not include lateral 
bracing.  Also contributing to the accident was CDOT's 
failure to effectively oversee safety-critical contract 
work.

        "This accident shows us just how important it is to 
have very clear guidelines about what is required for safe 
operations," stated NTSB Acting Chairman Mark V. Rosenker, 
"Sometimes it seems like such common sense that we wonder 
why we need these guidelines, and then we see an accident 
like this one."

        On the morning of May 15, 2004, a steel girder that 
had been installed about 3 days earlier and secured with a 
temporary bracing system, sagged into the eastbound lanes of 
I-70 and struck a sport utility vehicle traveling along the 
roadway.  All three people in the vehicle, including a 2-
year-old child, were killed in the accident.  

        The girder had been installed as part of a bridge-
widening project managed by CDOT.  To perform the 
construction work, CDOT contracted with Asphalt Specialties, 
Inc., which subcontracted the girder installation to Ridge 
Erection Company, Inc.  

        Ridge's girder installation and bracing plan was 
inadequate and was not prepared or reviewed by a Registered 
Professional Engineer, nor was it required to be.  The lack 
of planning resulted in multiple problems for the Ridge crew 
during the construction process carried out on the night of 
May 11 to 12. The crew did not have the proper tools, and it 
inadvertently began installing a section of the accident 
girder backward. These situations delayed the projected work 
for that night, so Ridge did not complete the work intended 
for that night and had to secure the girder with a temporary 
bracing system, expecting to complete the girder 
installation work the next night. However, due to weather, 
this work was postponed, so the girder remained secured with 
the temporary bracing system for several days.  

        While constructing the temporary bracing system, Ridge 
had experienced difficulty anchoring the bracing to the 
severely degraded bridge deck pavement. Postaccident 
examination also revealed that Ridge had installed the 
girder out of plumb. The braces, originally intended to 
secure a correctly installed girder for hours rather than 
days, failed causing the girder to sag into the roadway.  

        As a result of its investigation, the Board 
recommended that the Federal Highway Administration, the 
Occupational Safety and Health Administration (OSHA), and 
the American Association of State Highway and Transportation 
Officials (AASHTO) work together to develop consistent 
guidance and requirements for constructing such temporary 
highway bracing and related structures, known as 
"falsework," including that all falsework plans should be 
prepared or approved by a Registered Professional Engineer.

        The Board also cited CDOT's failure to oversee safety-
critical portions of the project because CDOT's on-site 
supervisors were aware of the problems Ridge experienced but 
did not question the adequacy of the work done by the 
subcontractor.  The Board recommended that AASHTO revise its 
guidance concerning oversight conducted by highway 
supervisory construction personnel to call for 
prequalification of subcontractors; submission of engineer-
approved written plans for all construction, including 
falsework; intervention when contractors or subcontractors 
demonstrate a lack of competence; and monitoring of 
temporary bracing systems until construction is completed.

        A synopsis of the Board's report, including the 
probable cause and recommendations, is available on the 
Board's website, www.ntsb.gov.  The Board's full report will 
be available on the website in several weeks.

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Media Contact:  Lauren Peduzzi
                        peduzzi@xxxxxxxx
                        (202) 314-6100




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