Bridging the Gaps in Bridge Working Safety
While bridges make our daily lives easier and safer, building and maintaining bridges creates a long list of potential hazards for workers. In addition to the hazards already associated with highway work zones and other types of structures, bridges are nearly always elevated — often substantially so — creating a risk for falling off of them.
Given that much of the work being performed on a bridge involves elevated surfaces, providing fall protection is a top priority. And because work is generally not limited to one area, fall protection systems need to accommodate worker movement. That’s why horizontal lifeline systems are often an excellent choice, whether they are temporary systems to be used during bridge construction or with major repair projects, or permanent systems that remain in place to facilitate regular maintenance and inspections.
Installing a horizontal lifeline is a more complicated process than many people believe. Workers will need multiple anchorage points, and the system must be able to support the loads that will be applied to those anchorages. Systems must also account for the amount of clearance below the surface where work is being performed, and potential rescue procedures must also be considered.
Temporary lifeline systems typically include a cable that runs across the length of the jobsite, giving workers the ability to tie-off where needed. The cable, normally made of stainless or galvanized steel, should be at least 3/8 inch in diameter. It’s attached to a series of stanchions that often allow workers to bypass them without disconnecting their protection, and ends at terminations strong enough to accommodate potential forces. In-line shock absorbers are normally used to limit horizontal forces caused by a fall, although they increase the amount of clearance that’s needed.
Permanent lifeline systems are similar. They also use stainless steel cables that stretch across the worksite, with sleeves that make it easier for workers to move along the cables. Intermediate brackets are used to add stability, while the cable terminations often have built-in shock absorbers and tensioners.
With both systems, the workers should use a full-body harness with a shock-absorbing lanyard or a self-retracting lifeline. While this equipment must be able to safely suspend the worker, it should also be comfortable and not interfere with the performance of tasks, so workers don’t hesitate to wear it. It’s important that workers receive training on both the proper use of fall protection and on proper rescue procedures. A worker suspended in a fall protection harness begins to experience physiological responses that, according to an OSHA technical bulletin, could be fatal in just 30 minutes.
Specialized safety equipment
Contractors that frequently perform work on bridges would be wise to invest in the systems that have been designed to help workers safely access areas that may otherwise be difficult to reach. The enhanced sense of safety these devices provide make it easier for workers to concentrate on the tasks they have to perform, enhancing productivity.
Examples include hydra platforms and bridgewalkers, which can lower a platform below the surface of the bridge, giving workers room to move while performing tasks under the bridge deck or on support structures. Snoopers and other under-bridge inspection trucks, which are similar to bucket trucks, offer a safe way to access the underside of even very high bridges.
If the work is being conducted over a stream or other body of water, there may also be a need to station a rescue worker in a boat below the work area.
Personal Protective Equipment
It’s interesting that one of the first construction projects that specified the use of PPE was a bridge. In 1933, as construction began on the famed Golden Gate Bridge between San Francisco and the Marin County headlands, the project’s chief engineer demanded that all workers wear hard hats.
Wearing the appropriate PPE is still a critical component of bridge safety, and hard hats are a common choice. OSHA rules call for the use of hard hats on working being performed on bridges when there’s a potential for falling objects, they’ll be in the vicinity of live electrical equipment, or it’s likely that they could bump their heads on structural members. In addition, eye and face protection is mandated during most operations, because the type of work that’s performed on bridges typically creates exposures to particles, other foreign objects, sparks, and high winds. Safety shoes or other foot protection are also required in most settings.
Depending on the specific environment and the tasks that are being performed, crews may need additional protective equipment. Many bridges carry utility lines and pipes in addition to traffic, and construction equipment may damage those lines or pipes. Workers should have access to fire control equipment, such as fire blanketing, to allow them to immediately extinguish any fires that occur due to utility damage.
Because many bridges continue to carry traffic while work is being performed, steps must be taken to separate the workers from the traffic flow and to ensure their visibility. Barricades and other traffic control devices can provide a safe distance between drivers and workers. High-visibility clothing and reflective vests call additional attention to the presence of the workers, reducing the chances that they’ll be struck by a motorist.
Finally, both workers and utility lines benefit from the use of under-bridge protection systems such as cages that surround the utility lines. These systems reduce the possibility that a worker or a piece of equipment will come in contact with the utility line, assuring the worker’s safety and preventing costly outages.