Construction Related Falls
Overview of Fall-Related Accidents in the Construction Industry
Working in the construction industry involves taking risks. Construction sites are paved with dangerous maneuvers that cause serious injuries and sometimes death. Construction workers are tasked with handling heavy machinery, bulldozers, jackhammers and other equipment that demand energy expenditure lest they get fatal wounds (Osha.gov, 2014). Workers do not have a choice but to look behind their backs. This is in case of any imminent danger from either from the equipment they are handling or emanating from the construction items such as bricks. Out of the statistics recorded by United States Department of Labor, fall–related accidents contribute a good proportion to the deaths and injuries suffered by construction workers (Ntsb.gov, 2014).
United States Department of Labor works in collaboration with occupational safety and health administration to oversee prevention, protection and compensation of construction workers when they suffer from fall related accidents at work. OSHA confirms that are the leading cause of the deaths in the construction industry. The organization notes an annual average of 300 deaths from fall-related accidents within the construction industry alone. Therefore, falls are the top suspect in the construction industry and remain the greatest hazard that construction workers face on a daily basis. Construction work involves handling bricks, steel and cement as well as heavy machinery several stories above the ground level (Osha.gov, 2014).
OSHA department also notes scaffolding accidents, misuse of portable ladders and steel bars that protrude haphazardly in a building or a general construction site. It has proposed measures such as safety-net system, guardrail and personal fall arrest systems within any site that involves several stories above ground zero. They help to minimize impact and the overall bodily in the event the fall takes place (Osha.gov, 2014). The role of United States Department of Labor is to ensure that fall related standards are adhered to without comprise whatsoever
This confirms that fall-related accidents are a major problem in the construction. In light of fall-related, the I-35W bridge collapse on road users in the Minnesota Twin Cities metropolitan region shall be discussed.
Review and analysis of the I-35W bridge collapse on road users in the Minnesota Twin Cities metropolitan region
How the I-35W bridge collapse happened
I-35W Bridge collapsed in august 2007 on the Mississippi river in Minneapolis, city of Minnesota. The bridge serves the university of Minnesota, commuters and drivers en-route to and fro Minneapolis. The bridge collapse did not only cause deaths of commuters and drivers on the road that day but also resulted to a serious traffic problem to and from suburbs of Minnesota (Xie & Levinson, 2011). The immediate injuries and economic costs calculated from the accident resulted into worse economic index save for the loss that occurred in subsequent days before the problem was rectified.
Effects of I-35W bridge collapse
The accident halted any passage by both commuter service and personal car drivers in and from the region (Xie & Levinson, 2011). The traffic jam then extended to the regions neighboring Minneapolis city. All the transport services that used to use the bridge were directed afresh to other alternative routes. However, that did not ease the congestion build-up in the region. Commuters has to learn without choice on when to switch departure or arrival to the city on the basis of time, destinations and modes to avoid the traffic that would take a few hours to build up.
Traffic department saw the essence to switch traffic to alternatives routes without considering the distances commuters would cover. Commuter and drivers did not any choice but to adjust to trip destinations that demand more fuel consumption than they used to. The fuel cost coupled with time delays caused major losses in the business situated in Minneapolis. However, the problem came with convincing people to adjust their destinations or trip. Therefore, the cost rose to between 71,000 to 220,000 US dollars per day (Xie & Levinson, 2011).
The Department of Transport In Minnesota was tasked with restoring the bridge so that it could save costs incurred by over 140, 000 travelling in and out of Minneapolis daily. However, the restoration efforts caused an unprecedented strain in their kitty (Ntsb.gov, 2014). The challenge of restoring the bridge emanated from the pressure from the government and commuters. It had to work day and night without compromising on the quality of the work. Planning in situations of emergency called for quick spending plus proper strategies.
The transport department was also supposed to come up with alternative networks to contain the traffic. The unplanned network made the city susceptible to terrorist attacks and potential natural disasters. Infrastructural failure took place because commuters tried to dodge traffic, violated traffic laws and even caused accidents in efforts to escape from the delay caused by the I-35W bridge collapse (Xie & Levinson, 2011).
Cost Evaluation for I-35W Bridge Collapse
There was transport, economic and individual losses emanating from the accident. Given that 1400,000 people use the bridge crossing on a daily basis, the department of transport in Minnesota estimated costs to sum up to 400,000 US dollar per day (Xie & Levinson, 2011). Road users had to change trips, destinations in response to the absence the bridge crossing. They had to do it with a high level flexibility to avoid extra costs than they were already incurring. Moreover, there was payment to be done to remove and reconstruct the bridge. This called for another kitty to pay the best contractors to work on the fall accident. The payment had to be prompt to avoid any digression from the estimated date of completion and replacement of the bridge. Quality interchanges, widening and permanent ramps are some of the logistic entities that contractors needed to consider but in general it demanded for more expenses (Zhu, Tilahun, He & Levinson, 2012).
Causative Factors for Interstate I-35W Bridge Collapse
There were mixed reactions about the cause of the collapse. The collapse attracted reactions from public, structural engineer and media (Zhu, Tilahun, He & Levinson, 2012). The collapse happened so fast that the public thought it was another terrible terrorist attack since 9/11 but that was a quick speculation. However, structural engineers and authors wanted to get to the bottom of the matter and proposed the following causative factors;
The fault was attributed to the gusset plat connections and the truss links within the chain structure of the bridge. The failure of the truss members within the chain caused the weak connection of the gusset plates within the steel bridge (Ntsb.gov, 2014). Engineers focused more on U10 notes in all the connections. The stress was also caused further by weight of the traffic passing on the bridge coupled with concrete filling up the bridge. There was a possible fault on the design and connection of truss and gusset plates leading to the collapse. Structural engineering faults are allowed but not to an extent of causing an unprecedented bridge collapse.
The repair and constant modifications since its construction
In order to prolong and maintain it service life, I-35W Bridge called for frequent repair and modifications. Notably, the 1977 and 1998 reconstructions were investigated by National Transportation Safety Board. There reconstructions increased the thickness of the bridge to 8.5 inches. This increased the overall weight of the bridge; the traffic using the bridge plus the excessive concrete weight compared to the steel used to construct the bridge initially. The excessive weight brought about by the reconstructions is thought to have initiated the bridge collapse. The mechanical problem was later identified by structural engineers tasked with the replacement work (Ntsb.gov, 2014).
The nature of the gusset plates used for connection purposes
The investigation carried out by structural engineers and the national transportation safety board focused on the failure of gusset plate connection with U10 nodes. The team carrying out the investigation tested the elasticity and plasticity as well as structural design guidelines that were used in the construction of the bridge. The plates are suspected to have suffered plastic collapse. Plastic collapse occurs when there is an increase in the rotation in the hinge eventually resulting to breakage of the connection clips (Zhu, Tilahun, He & Levinson, 2012). The analysis was carried out by used of thorough computer analysis. The extra force coming from the excessive weight prompted the deformation of the plastic detail leading to disconnection of the gusset plates.
Road construction that took place during the day of the collapse
The road work that was taking place during the time of collapse is also thought to have contributed to the destruction of the interstate crossing. According to National transportation Safety Board (2014) the construction equipment and aggregates were delivered. The roadwork also meant that one of the lanes had to be closed. The indifference in weight of road work items and utilization north and south bound lanes contributed to the separation.
The federal and state transportation officials noted other possible causative factors such as temperature indifferences, cracks existing in the bridge that went unnoticed, truss fracture, corrosion of the plate nodes and movement of concrete piers.
A Sample Fall Protection Program for I-35W Bridge Collapse Accident (Osha.gov, 2014)
- Avoid or limit concentration of weight for construction materials used
One of the suspect causes of the bridge collapse originated from concentration of weight of materials used for roadwork that day. If the eventual effects of concentration of the roadwork materials had been noted, the collapse may have been prevented in advance.
- Approved written authority for staging materials on the bridge
There should be permission for any contractors or road work team willing to stage materials on the bridge. This would reduce the overly pressure applied on the gusset plate by the staging materials
- Come up with a design review for gusset plates
The design of the gusset plates and steel items should be double checked before use.
- A compulsory bridge instruction training for all bridge construction inspectors
This would enable to deliver proper oversight when investigating bridge construction at a later stage (Zhu, Tilahun, He & Levinson, 2012). The training would give the officials ability to assess the state of the bridge accurately.
- Checklist to aid in design review
A checklist should be prepared in advance to put down all the materials that require design review before construction work takes place. The design review checklist ensures that proper calculations are done and out into effect during construction.
- Proper analysis of the gusset plates
Plasticity, elasticity and ability of the plates to withstand pressure should be analyzed to enable the construction officials to note changes on the plates and prevent future collapse. The gusset plates should also made to withstand the weight of other parts such as concrete and steel in the truss structure.
It is also important to train construction officials on the process of inspecting gusset plates to help mitigate any possible failures of the plates. This way the officials can offer proper guidance on the right strength of gusset plates to use.
- Explain the role of the preliminary designs of the bridge
There is a possibility the preliminary blue print of the bridge was utilized for constructions leading to malfunctions that lead to collapse. Only the official designs should be used to put the bridge together.
- Constant recheck and informed reconstruction procedures
Only proper expertise should be used in the reconstruction program in case the bridge demands any. The bridge should also be checked on regularly and modern structural engineering expertise utilized in the entire process.
There is no doubt that construction industry records deaths and injuries caused by fall hazards alone. The intervention of United States Department of Labor and the need for construction companies to consider safety programs such as OSHA has been seen. The research on I-35W bridge collapse has shown the eventual losses that such an accident can cause. Without emergency plans such as proper funding and expertise in the area such a fall accident can cause permanent damage to the city of Minnesota and neighboring states.
The causative factors resulting from the failure of the structural materials and human contribution into the accident has been noted. Such a state problem does not call for the officials to point fingers at contractors because the problem can be prevented in future through a proper protection plan. Coming up with the fall protection plan for such an accident is one thing and implementing the safety and protection plan to prevent such disasters is another. The challenge lies with the construction officials.
The need for a fall protection plan
Fall hazards and construction accidents such as I-35W bridge collapse cause economic and life losses that cannot be recovered. A fall protection plan is essential because it helps to prevent the possible in a high prone risky area such as a construction site. A comprehensive fall protection plan is a mitigation program for the safety of the employees, company and the general public. It is meant to stipulate protection goals, define clearly the best fall protection system in line with the potential risks and train staff effectively to implement the plan.
Ntsb.gov., (2014). Accident Investigations - NTSB - National Transportation Safety Board. Retrieved 16 May 2014, from http://www.ntsb.gov/investigations/summary/har0803.htm
Osha.gov,. (2014). Fall Protection. Retrieved 16 May 2014, from https://www.osha.gov/doc/outreachtraining/htmlfiles/subpartm.html
Xie, F., & Levinson, D. (2011). Evaluating the effects of the I-35W bridge collapse on road-users in the twin cities metropolitan region. Transportation Planning And Technology, 34(7), 691-703. Doi:10.1080/03081060.2011.602850
Zhu, S., Tilahun, N., He, X., & Levinson, D. (2012). Travel Impacts and Adjustment Strategies of the Collapse and the Reopening of the I-35W Bridge. Springer, 21--36.