Some construction equipment lead boring lives. Destined to spend every day going forward and backward, backward and forward, their repetitious cycle can lull even the safest operator into a road-hypnosis state or even a quick-nod moment.
Scattered along the Monotony Trail are numerous safety risks, some visible to the machine operator, some not, but all creating a potentially dangerous situation, especially with objects hidden in blind spots around the machine, such as a person, a mound of rocks, a stack of pallets, or a wall.
For years, personal protective equipment (PPE) such as hard hats, gloves, slip-resistant surfaces, safety clothes, shoes and glasses, among others, have protected heavy-equipment workers in construction, industrial, steel working, mining, and marine industries. Today, technology is providing even more opportunity to keep workers safe.
One such unit, a wristband from Caterpillar, uses data yielded by sleep studies to help detect fatigue in a worker who is too tired to perform his job safely. Depending on the severity of the fatigue, equipment managers or supervisors can move a person temporarily off his regular job and assign him to other, less dangerous duties. If extremely severe, the supervisor can even send him home for the day. The wristband specifically measures the quality and amount of sleep the individual has had over a four- or five- day period.
Another device is a video camera that focuses its lens on a vehicle operator’s face, not any other area of the cab. The camera self-activates, but only if a person nods off or looks away too long from the road in front of him. The video, basically, helps stop drivers from running off the road.
As safety technology advances and improves, so does safety in the workplace. Among the most recent developments introduced in the construction and welding markets respectively are Caterpillar’s Detect for Personnel, a technology that helps mobile equipment operators avoid collisions with ground personnel and fixed objects. A new individual safety system, Lincoln Electric’s CrossLinc, is a welding technology used in industrial construction and fabrication yards, and PRECO Electronics introduced PreView Sentry for construction and PreView Side Defender for on-road applications.
According to Caterpillar, Detect is a passive system not based on magnetic field technology, which requires batteries to power electronic badges on the receiving end. Magnetic field technology is a captive tech system that “is more of a general proximity detection system,” says Mark Dowsett, safety technology representative for Cat Detect for Personnel. The Cat passive system, on the other hand, “is unique with its focus on the primary blind spot or spots,” he says.
“We especially wanted to target people and prevent them from being hit by a machine,” he says. “It’s all about people, and, at the end of the day, what we are trying to do is use technology to change human behavior.”
To do that, Dowsett says, the operator has to trust the technology, and the warning alert itself has to be sudden and unexpected.
“I have visited several construction sites, and frankly, on-site workers get numb to what they are hearing. The ‘beep-beep-beep’ of a vehicle backing up is a good example. They hear back-up alerts so often they tune them out and pay little attention to them.”
With the Detect system, employees working inside the red zone, or high-risk area, wear vests or hard hats imbedded with radio frequency identification (RFID) tags. Tags are pre-stitched into a standard-type vest across the front, up and over the top, and down the back.
“The reason we have the tags all over the vest is because the UHF signal has two inhibitors, metal and water, and the body is made up mostly of water,” Dowsett says. “If you add tags only on the front side and your back is turned to a skid steer, for instance, you would not be protected.”
The other option is to place 12 tags inside the hardhat brim. “That way, if someone trips and falls and the hard hat is knocked off and lands in the red zone, there are still 12 opportunities to be detected,” he says. The tags, which bend and have a piece of adhesive backing, are attached to the interior liner of the smooth finish of a standard hard hat.
If someone steps into the finite, pre-determined zone, an antenna mounted on an adjustable bracket emits a low-frequency signal that picks up the RFID tags worn by the crew. The signal can also detect fixed objects that enter the danger zone.
The signal beam is narrowed to 25 or 30 feet out from the antenna and about 10 feet side-to-side, says Dowsett.
“The beam can be adjusted by tipping the antenna down. Otherwise, it will extend out 30 feet. I have seen the UHF beam narrow down to six or eight feet,” says Dowsett. “That is the difference between passive and active RFID, no batteries required and beam adjustments can be done on the fly.”
Unlike active systems, the passive system simply reflects the signal that goes out, bouncing it back from the person or object.
When the alert goes off inside the confined cab space, lights flash and a loud alarm notification warns the operator. At the same time, a 96-decibel external alarm notifies the outside work crew, says Dowsett. The alarm gives out a high “whiney” sound that is different from the beeps of a back-up alert. The PPE alarm, which Dowsett describes as similar to a fire alarm in a building, won’t stop blaring until the worker moves to a safe place.
Caterpillar uses rigid RFID tags to keep equipment from striking such fixed objects as light poles, portable generators, pickup trucks, pillars for overpasses, etc. The rigid tags are the same as the personnel RFID tags, except they are embedded in hard, plastic cases that have screw holes as well as adhesive backing attachments, says Dowsett.
Reports coming back from field tests and construction sites where the technology is already installed are very good, Dowsett says.
“During the first week the system was installed, a subcontractor on an Exxon Mobile project in Houston started getting 50 or 60 alarms going off a day,” Dowsett says. “They called time out, talked to the crews and then did three things: retrained the people, adjusted the antennas simply by tipping them down to the narrow beam, and adjusted the traffic flow patterns where the incidents were occurring.”
By the end of the third week, says Dowsett, the alerts were down to four or five a day.
In a totally different environment, Wayne Chuko, Lincoln Electric’s product manager for industrial inverter power source lines, says that both the recently introduced Flextec products using CrossLinc technology have an X in their identify designators.
One is the LN-25X, a welding wire feeder, and the other is Flextec 350X, a welding power supply source that incorporates a smaller energy-efficiency inverter. The Flextec can be configured in one rack of four individual units, two on top and two on bottom. From there, welding leads go out to the locations on the job site where the welding operators are performing.
“That distance could be, typically, about 200 feet from the power source,” Chuko says. “One safety aspect is that you have only one high-volt power line coming out and from there, in this case, four low-voltage lines stretching in different directions across the 200 feet to the different welding areas. That’s where CrossLinc technology comes into play.”
On construction sites, as a rule, the process of stick welding and flux-cored wire welding are most common.
Lincoln Electric, however, focuses on what Chuko describes as “the very broad area of arc welding, which includes stick and wire welding in which you have a chain of electricity. The electrical arc touches metal to form the weld.”
For wire welding, the multiple, inverter power sources have two big copper leads running hundreds of feet across the site to another smaller box, the wire feeder. The feeder contains a spool of wire that weighs about 44 pounds. The wire spool is placed inside the wire feeder, which has a motor that spins and pushes the wire out. The wire touches the metal and melts in conjunction with the base material being welding.
To make a good weld you need the right wire, the right wire diameter, the right machine, the right setting on the machine that tells you how fast the wire is coming out, and a skilled welder, Chuko says.
“Over long distances, there can be some voltage drop due to electrical resistance that differs from the setting you selected on the power source,” he says. “The result is the weld may be hotter, or not, than you expected.”
To complicate the process even further, weld parameters differ from weld to weld. For instance, if welding something on a flat surface, the parameters will differ from welding upward or vertically. “You have to change voltage and wire feed speed settings, depending on the angle,” he says.
Usually, to set up correctly, the welder has to walk the long distance back to the source, increase the voltage slightly, come back, and hope he increased it enough to do the job.
Not only is that inconvenient, it reduces the productivity level, and from the safety perspective, workers have to step over the stretch of cables, upping the risk of trips, slips, and falls.
“Of course, all that activity leads to a lot of downtime, but there are alternatives, such as our LN-25X Pro.”
Reprinted with the permission of Equipment Manager magazine, the magazine of the Association of Equipment Management Professionals.
That portable wire feeder reduces setup time and, “you don’t have twice as many cables on the ground cluttering up the job site,” says Chuko.
PreView Radar is a radar-based collision mitigation safety technology designed, engineered, and manufactured by Preco Electronics.
PreView Sentry was introduced at MINExpo and PreView Side Defender at CONEXPO-CON/AGG, says Tamara Humphreys, marketing manager, Preco Electronics. Sentry is primarily used as a rear blind-spot detection system and can provide up to 360 degrees coverage when multiple sensors are installed on a machine. Side Defender is designed for on-road object-detection applications.
“Sentry sensors include five proximity zones that actively alert the operator of the closest hazard to the sensor,” says sales manager Sean Martell. “The five zones illustrate to the operator if the object is moving toward the sensor, away from the sensor, or not moving in the sensor’s blind spot detection area. If you were to take a 20-foot radar zone and divided it by five, for example, then each of the zones is about four feet. The zones are illustrated on the in-cab monitor or display and actively inform the operator of the general direction of the hazard.”
The on-road Side Defender is specifically designed for roadway traffic, allowing it to ignore stationary objects such as guardrails, when the vehicle is moving over 10 mph. This reduces the number of nuisance alerts. Both systems use Frequent Modulated Continuous Wave (FMCW) technology, says Martell.
“What makes Preco’s systems different is they have been engineered to detect hazards up to the face of the sensor itself. And human detection is priority No. 1,” he says.
“Safety is so important, all Preco radar systems are built with full-scale features that alert the operator if there is sensor blockage or communications failure between the sensor and the cab display. On Side Defender, the zone detection is set. The on-road technology alerts the driver if objects are moving in side blind spots, whether it be a turning application or in lane change situations.
Frederick Energy Products’ Hit-Not system is based on low-frequency magnetic field technology initially developed for the mining industry. Hit-Not is able to read and send warning signals through walls, racks, and other blind corner obstructions. The collision detection system uses a stable magnetic field marker.
Another backup system that specifically targets people rather than fixed objects is Scan-Link Armour, which sounds an alert when the vehicle is backing up. The sensor/antenna unit is housed in a sealed, waterproof enclosure. The sensor unit is designed to detect Scan-Link safety apparel and uses a wireless link to relay information to a display unit located near the equipment operator.
The display unit uses both an LED visual display and an audible alarm with adjustable volume. Alerts go out instantly if someone wearing a Scan-Link tagged vest or hardhat enters the red zone.
Taylor Machine Works Vision Plus system also ignores objects and alerts equipment operators and nearby workers if someone is in a danger zone, which the manufacturer says significantly reduces the number of alarms that go off. Vision Plus can be used on any industrial vehicle, including fork lifts, reach stackers, cranes, and mining and construction equipment.
Using a series of cameras mounted in various locations on the equipment, the operator is able to monitor pedestrian activity around his vehicle by using a display unit mounted in the cab. Distinct audible alarms and a system of warning lights tell the operator and pedestrians that someone has entered the operating range of the machine.
Although a variety of systems are now in the market, all said, PPE technology is a good crossing guard to have around.
