This Week’s Bridge Collapse at the FIU campus in Miami, Florida has focused national attention on a construction accident. At this time the cause of the collapse is unknown, but news reports have provided interesting and concerning details about this bridge construction project.
Detail #1 – Quick Construction- It was built using a method known as “accelerated bridge construction” — an innovative way to build bridges more speedily than with traditional building methods. While support columns were constructed on both sides of Tamiami, the 175-foot span was built on the side of the road. In a matter of hours Saturday morning, the span was installed onto the columns.
The accelerated bridge construction (ABC) approach has become more common in the past 10 years, particularly in urban areas with heavy traffic, said Ralph Verrastro, a Cornell-trained engineer and principle of Naples-based Bridging Solutions.
“That’s the driver and why ABC is so popular, because it allows you to keep the road open,” he said. “It’s more expensive to do, but it gains the advantage of keeping traffic moving and that’s what makes the phone ring at the mayor’s office.”
Detail #2 – Materials Used: “The loads have to be calculated precisely in the analysis to make sure the partial bridge would be able to carry them safely,” said Amjad Aref, a researcher at University at Buffalo’s Institute of Bridge Engineering.
Because precision is key, multiple factors may have contributed to the bridge failure. The investigation, Aref said, will need to examine the construction sequence, testing, environmental conditions such as wind and other possible factors.
“It might not be one factor,” he said. “It could be a combination of things.”
The bridge also had some unusual design features.
The bridge’s superstructure was something Verrastro said he’s not seen in 42 years of designing bridges. Rather than using steel trusses, it employed heavier concrete trusses. The bridge also had a concrete roof, adding even more weight.
“This was a very long span and then they used very heavy material,” he said. “The majority of pedestrian bridges are steel.” Steel bridges are about one-tenth the weight of concrete, he said.Read more here: http://www.miamiherald.com/news/local/community/miami-dade/article205422719.html#storylink=cpy
However, in almost all bridge or building collapses, he added, construction is at fault, not design. The flattened bridge will likely remain in place, he said, while a forensic engineer conducts an investigation. Read more here: http://www.miamiherald.com/news/local/community/miami-dade/article205422719.html#storylink=cpy
This kind of construction accident is not usual and does not account for the statistical majority of construction related accidents.
Construction’s “Fatal Four” Comprise More than Half of Construction Fatalities
Out of 4,693 worker fatalities in private industry in calendar year 2016, 991 or 21.1% were in construction — that is, one in five worker deaths last year were in construction. The leading causes of private sector worker deaths (excluding highway collisions) in the construction industry were falls, followed by struck by object, electrocution, and caught-in/between. These “Fatal Four” were responsible for more than half (63.7%) the construction worker deaths in 2016, BLS reports. Eliminating the Fatal Four would save 631 workers’ lives in America every year.
- Falls — 384 out of 991 total deaths in construction in CY 2016 (38.7%)
- Struck by Object – 93 (9.4%)
- Electrocutions – 82 (8.3%)
- Caught-in/between* – 72 (7.3%)
(*This category includes construction workers killed when caught-in or compressed by equipment or objects, and struck, caught, or crushed in collapsing structure, equipment, or material)
Top 10 most frequently cited OSHA standards violated in FY 2017
The following were the top 10 most frequently cited standards by Federal OSHA in fiscal year 2017 (October 1, 2016, through September 30, 2017):
- Fall protection, construction (29 CFR 1926.501) [related OSHA Safety and Health Topics page]
- Hazard communication standard, general industry (29 CFR 1910.1200) [related OSHA Safety and Health Topics page]]
- Scaffolding, general requirements, construction (29 CFR 1926.451) [related OSHA Safety and Health Topics page]
- Respiratory protection, general industry (29 CFR 1910.134) [related OSHA Safety and Health Topics page]
- Control of hazardous energy (lockout/tagout), general industry (29 CFR 1910.147) [related OSHA Safety and Health Topics page]
- Ladders, construction (29 CFR 1926.1053) [related OSHA Safety and Health Topics page]
- Powered industrial trucks, general industry (29 CFR 1910.178) [related OSHA Safety and Health Topics page]
- Machinery and Machine Guarding, general requirements (29 CFR 1910.212) [related OSHA Safety and Health Topics page]
- Fall Protection–Training Requirements (29 CFR 1926.503) [related OSHA Safety and Health Topics page]
- Electrical, wiring methods, components and equipment, general industry (29 CFR 1910.305) [related OSHA Safety and Health Topics page]