Roadway work zones are hazardous both for motorists who drive through the complex array of signs, barrels, and lane changes and for workers who build, repair, and maintain the streets, bridges, and highways.
A blind spot (or blind area) is the area around a vehicle or a piece of construction equipment that is not visible to the operator, either by direct line-of-sight or indirectly by use of internal and external mirrors.
Construction equipment is typically large and has an enclosed cap. This can make the blind areas around the equipment very large and hard to see. The bigger the equipment, the larger the blind spots or hazardous areas for pedestrian and ground workers.
Here is a complete list of construction vehicles and blind area diagrams: Construction Equipment Visibility-Diagram Lookup.
Obstructions in a driver’s line of sight might be one of the following:
Tools and attachments on vehicles can also create greater blind spots, reduce visibility, or swings that can increase the risk to workers being struck or pinned. You must know the equipment swing radius, such as how far can it reach, move, or rotate.
Here are a few ways to protect yourself when working near heavy equipment:
According to BLS, between 1995 and 2002, dump trucks were responsible for 41% of “worker on foot” related deaths. 52% of these involved dump trucks backing up.
If employees are in the backing zone or it is reasonable to expect employees will enter the backing zone behind a dump truck, the vehicle must have an operable automatic reverse signal alarm which is both audible above the surrounding noise level and can be heard at least fifteen feet from the rear of the vehicle.
You must also have an observer who signals when it is SAFE to back up or stop OR the vehicle has an operable device installed which gives the driver a FULL VIEW of the area behind the dump truck.
In October 2006, a 28-year-old laborer was backed over by a tack truck while working as a flagger on an asphalt resurfacing job in a residential roadway work zone. The victim was standing with his back to the reversing tack truck when a dump truck driver attempted to warn him by waving his arms. The tack truck struck the victim; the driver thought he had passed over a manhole cover and continued backing. The tack truck driver stopped when he saw the dump truck driver running and waving his arms in his mirror. Both drivers found the victim at the front of the tack truck lying face down on a man-hole cover on the ground.
Spotters are a proven method of protecting employees on foot behind vehicles with an obstructed view, but spotters themselves can be at risk for injury or even death. Employers can implement the following actions to help keep spotters safe:
Below are some common spotting signals:
Most vehicles (and some types of mobile equipment) can accommodate a camera that provides operators with a view to the rear. Some vehicles come equipped with cameras or may be offered with them as optional equipment. Camera systems can also be purchased as after-market equipment for vehicles.
Viewing screens may be dash-mounted but must not block the driver's view out the windshield. Harsh environments, such as some construction sites or mines, may require more rugged cameras. Determining where to mount a camera for maximum effectiveness may be difficult, especially on large vehicles. For example, dump trucks may require two or three cameras to monitor the blind spots on the front, rear, and side of the vehicle.
Radar and ultrasonic technology both are used in backing safety systems. A radar system transmits a signal, which is bounced off an object. The signal is then received by a receiver. These systems alert the driver with a visual and/or audio warning. These systems must be positioned so that they won't detect harmless objects, such as the concrete slab of a driveway, which can interfere with the detection of an object or person behind the vehicle or mobile equipment. Also, the composition of an object can affect detection, with some materials being virtually invisible to radar. Like cameras, this equipment can be mounted on most vehicles and may be an option from some equipment manufacturers.
Ultrasonic systems, such as sonar, emit bursts of ultrasonic waves in a frequency above the hearing threshold of humans. When the waves strike an object, they generate echoes used to determine the distance to the object. These systems alert the driver with a visual and/or audio warning.
Another type of proximity detection system is an electromagnetic field-based system, which is a type of tag-based system. This system consists of electromagnetic field generators and field detecting devices. One electromagnetic field-based system uses electromagnetic field generators installed on a vehicle and electronic sensing devices (a tag) worn by persons working near the vehicle. Another electromagnetic field-based system uses field generators worn by persons working near the vehicle, with the sensing devices installed on the vehicle. These electromagnetic field-based systems can be programmed to warn affected workers, stop the vehicle, or both, when workers get within the predefined danger zone of the vehicle.
An internal traffic control plan (ITCP) is another method used to address backover hazards. These are plans that project managers can use to coordinate the flow of moving equipment, workers, and vehicles at a worksite to minimize or eliminate vehicles and employees from crossing paths. These plans can significantly reduce, or possibly eliminate, the need for vehicles to back up on a site.
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