A portion of the Skagit River Bridge, located in Mount Vernon, Washington catastrophically collapsed into the water below after a semi hauling an oversized load clipped a cross beam in 2013. Luckily and amazingly, no one was killed by the incident, but 3 people were taken to the hospital for minor injuries as several cars fell into the river. It took over 3 years to determine a cause and the report states that there were several causes. First, below is security camera footage of the collapse, uploaded to Youtube by newschannel500, in which you can see just how quickly the collapse happened.
It’s one thing for a structure to suffer damage and slowly collapse, but this happened so quickly it left many scratching their heads. By code, all structures and buildings are designed with a factor of safety to allow occupants to react and exit safely.
Illinois civil engineering professors Tim Stark, Ray Benekohal, Larry Fahrenstock, and Jim Lafave recently published their findings in the American Society of Civil Engineers’ Journal of Performance of Constructed Facilities. The team of engineers concluded that a combination of regulatory factors, structural issues, and human error all contributed to the failure.
“The bridge repair costs exceeded $15 million, and that doesn’t account for the economic losses that the area felt because they and visitors no longer had access to the interstate," Tim Stark said in a statement. “Even though this accident occurred three years ago, it’s still very important because many bridges have this same design, not only in Washington but in other states.”
Permits are issued to trucks that meet specific criteria for the structures on their route, including the height of their truck. Even though the truck was under the maximum clearance the Skagit River Bridge allows, the maximum clearance on the outside lanes was much shorter. The problem is that, unlike many bridges, the clear height was not consistent across the width of the road. The top was arched, allowing a clear height of 17 feet 3 inches in the center lanes, but only around 15 feet 3 inches on the outside lanes. The truck was 15 feet 9 inches tall, which allowed it to hit the cross beam. The State of Washington DOT only kept the maximum height of the bridge in their database, as opposed to the lowest height like other states, including Illinois, do.
Although one of the cross beams was badly damaged by the truck, it was not actually a primary structural component, according to Jim Lafave. However, the way it twisted caused the bridge truss to be pulled down with it, causing the section to fall.
Oversized trucks are accompanied by a pilot car to help guide them and alert them of any dangerous situations ahead. In this case, the pilot car had an antenna at the same height as the truck, which is supposed to alert the driver if it hits anything. If the antenna hits something, then the driver of the pilot car calls the truck driver. According to Tim Stark, either the antenna did not hit the bridge or the pilot car driver did not hear it hit the bridge. Regardless of the reason, the truck driver was never called to adjust his route.
Based upon the engineers’ conclusions, they have also offered several recommendations to keep this type of event from happening in the future. All databases, they said, should be updated with the lowest clear height, pilot car antennas should be equipment with an automatic alert sensor, which would contact the truck driver immediately, avoiding human error, and several cross braces could be added to the design in order to avoid structural failure. You can also check out the video below, uploaded by Omega Morgan, to see how the bridge was repaired:
Full Story: Structural, regulatory and human error were factors in Washington highway bridge collapse | Illinois News Bureau
Back in September, OSHA issued a Notice of Proposed Rulemaking that would extend the deadline for crane operator certification requirements. Although OSHA 1926.1427 has required crane operators to receive certain certifications to be able to operate the machines since 2010, actual enforcement of that rule has been delayed several times.
Drywall, gypsum, sheet rock, wall board, or whatever you call it, has to be installed by someone, so who better than a drywall installer? Some drywallers install the board and also tape and mud the joints, but others only hang the board.
When sanding, drywallers are exposed to a lot of dust, including silica in some cases, which they need to be protected from. The Center for Disease Control suggests using a vaccuum sander or pole sanding to reduce worker's exposure to harmful dust particles
Roofers have one of the most uncomfortable jobs on any construction site, especially when installing a dark roofing material. A traditional black roof, either asphalt shingles or EPDM, can be up to 50 degrees warmer than the surrounding temperatures.
Having said that, let's take a look at how they're paid in each state...
The Netherlands has a ton of bridges, especially pedestrian and biking bridges, thanks to its abundant system of canals. Perhaps because of that, they have become a leader in 3D printing technology when it comes to bridges.
Painters are typically one of the last subcontractors on any construction site, who do their best to beautify the drywall with the colors of the architect's or interior designer's choosing. Some painters are also responsible for mudding drywall, patching holes, sanding, and caulking.
Let's take a look at how an average painter's hourly wage compares in each state...
Just one day after Mayor Bill de Blasio signed a new law requiring at least 40 hours of safety training for all 185,000 of the city’s construction workers, a partial roof collapse at a Brooklyn construction site left 6 workers injured, 2 of them serious.
Project managers and supervisors are responsible for keeping their employees safe and the court system has recently shown that they take that responsibility very seriously. When supervisors act in a negligent manner and people get hurt or killed, they should be held liable.
In doing the research for this analysis, I learned something interesting about the plumbing profession. The term "plumber" comes from the Latin word "plumbum," which means lead. Seems fitting in a profession, fairly or unfairly, stereotyped for exposed butt cracks.
In Roman times, plumbers often worked with lead for conduits, drain pipes, and making baths. Plumbers now work with a variety of different materials, including copper, PVC, ductile iron, among others.
It seems like every month there’s a new robot being debuted for the construction industry, with the promise of reducing costs and improving productivity and safety. There are robots for laying brick and block, placing concrete, and even self-driving mining trucks. The most recent robot to hit the job site is Built Robotics’ Autonomous Track Loader (ATL).
Concrete is an extremely strong building material, but has a notoriously weak tensile strength. In order to resist tension, bending, and shear forces, steel rebar or other reinforcement materials are added either prior to the placement or into the mix. Even with reinforcement, concrete is still extremely rigid and prone to cracking. In the event of a major earthquake, the uneven and horizontal forces can cause structures to crack and, in the worst case, cause failure.