Utility Worksite Safety Articles

When utility employees travel to remote backcountry job sites, things can turn bad quickly if they are not prepared to deal with hazards. And a bad situation can become exponentially worse during the winter months, when over-the-snow travel may be involved and additional factors – such as limited or failed communications, difficult terrain, winter storms, avalanche hazards and the potential for cold weather injuries – can potentially wreak havoc.

If employees are to understand how to safely handle these types of emergency situations, employers must diligently train and equip employees well before they travel to a backcountry site. For starters, all workers must be taught how to identify a survival situation. If a problem arises on a job site, lone employees or small crews with limited resources on hand should be trained to notify their operations centers to advise them of the problem, regardless of whether or not the employees believe they can overcome the issue on their own. This is a critical step that is often overlooked. Many times workers believe that walking back to the highway vehicle is the best option if they become stranded in the backcountry due to an equipment failure or operator error. This is almost always the worst thing to do, and many deaths have been attributed to such incidents. Traveling on foot in deep snow – which is incredibly difficult, if not impossible – should be the last choice, as crew trucks should have food, water and heat to last crew members several days of the worst-case conditions.

Beyond the basics of how to identify and address a survival situation, employers should also train employees about communication protocols, survival priorities, the appropriate survival tools to bring to the backcountry, and how to recognize and avoid cold weather injuries.

As a third-generation lineman in the high-voltage utility industry, I can say based on experience that the industry has changed slowly at certain times and radically at others. And yet one thing that has not changed much over the years is the process of performing live-line work on extra-high-voltage (EHV) transmission lines. It still requires the use of live-line tools; it still requires linemen to maintain minimum approach distances; it still requires that linemen possess the knowledge and ability to use tools properly depending on the application, whether it be steel or wood construction; and it still requires access to the energized end of the insulator string or conductor. For many years the method of accessing the “hot end,” as we call it, required the use of live-line-rated aerial lifts, horizontal or vertical live-line insulated ladders or, in some instances, helicopters. Each access method has its own set of intricacies that can be time consuming, labor intensive and costly, but all of the methods have the same end result when the procedure involves the bare-hand method for conducting the maintenance work. Live-line maintenance using the hot-stick method is another topic entirely, so for the purposes of this article, I am only going to address live-line bare-hand work.

Creating a New Tool
Well before OSHA’s final rule regarding 29 CFR 1910.269 and 1926 Subpart V was published in 2014, ushering in new fall protection standards, the live-line bare-hand committee within the company I work for – Tri-State Generation and Transmission, headquartered in Westminster, Colo. – began to think a great deal about providing our linemen with a new tool for performing traditional live-line work. Ongoing environmental and related job site concerns also impacted our thought process at the time. Those concerns included a lack of rights-of-way; earth disturbances caused by the need to access structures and set up aerial lift equipment; the possible need to re-vegetate earth that we disturbed during a job; lack of ability to de-energize transmission lines requiring live-line work; and the costs associated with the use of helicopters for routine live-line EHV maintenance.

The time the committee spent thinking about creating this new tool for live-line work was the beginning of developing Tri-State’s rope access and rescue program for live-line bare-hand work. Basic work methods did exist at the time, but we wanted a rope access program that provided greater training and direction and could include rescue at a level that hadn’t existed before but that we as linemen had always wanted. As time went on, we began to develop a comprehensive process for performing live-line transmission maintenance just as we had always done with ladders, trucks and helicopters, and it was – and continues to be – every bit as efficient, cost effective, rescue enabled and, most importantly, safe.

In the last installment of “Train the Trainer 101” (see http://incident-prevention.com/ip-articles/train-the-trainer-101-understanding-canine-behavior-for-the-protection-of-utility-workers), I provided information to help utility personnel understand, in part, why dogs do what they do. In particular, I addressed the pack mentality, dominant and submissive behaviors, and when and why a dog may feel threatened and try to attack. In the conclusion to this two-part article, I will explain how best to respond to unfamiliar dogs and what to do if you are attacked, as well as discuss breeds that are more commonly involved in biting incidents.

How to Respond to Unfamiliar Dogs
A dog’s response to a stranger will vary depending on whether he is with a handler or alone. When the dog is with a handler, remember what you know about the dog and human family relationship. The dog will respond to his handler’s actions as well as his own interpretation of an encounter with an unknown human. If you are the unknown human, speaking in casual tones to the handler, as well as the handler responding in a casual tone, will immediately set the dog at ease.

Workers in residential areas often are attacked by dogs who never posed a threat to people in the neighborhood. One reason behind this may be that workers focused on their task don’t exhibit the same mannerisms as visitors to the home or the people who frequent the property. This “unusual behavior” raises a dog’s suspicion and consequently his alertness level.

If you are walking toward a dog and his handler, stop a few feet away. If you are jogging or moving briskly, that may signal aggression to the dog. Stopping and allowing the handler and dog to approach you tends to reduce the dog’s alertness level.

I was recently asked to provide information about the challenges and opportunities found when working on direct-buried underground distribution (UD) systems. In light of that request, I’ll address those topics in this installment of “Voice of Experience.”

My first opportunity to work on UD systems was as a truck driver operating a trencher in the late 1960s. UD systems were fairly new at the time; lineworkers were learning new techniques, using different types of tools to terminate cables and installing switchable elbows. In that day, some elbows were non-load-break. Back then the work was all about proper use of tools, identifying equipment and following the minimum rules. There were no OSHA regulations. We learned many techniques and work practices the old-fashioned way: through the school of hard knocks.

The challenges that workers faced back then are much the same as they are today, with two exceptions: The industry has more experience installing and operating UD systems, and equipment is now much more technically sophisticated and reliable. For many years, maintenance of UD systems was nonexistent. The common approach was to dig a ditch and put cable in the ground, and industry workers believed everything would last forever. That belief was short-lived; within a few years, external concentric neutrals began oxidizing, and radial and loop-fed systems suddenly became single-conductor, earthen-ground return systems. Driven ground rods at transformers split coil for secondary voltages. There was no neutral conductor for return currents or fault current flow.

Q: We hear lots of opinions on whether a lineworker can lift a hot-line clamp that has a load on it. There is a rule that says disconnects must be rated for the load they are to break. We’ve been doing it forever. Are we breaking an OSHA rule or not?

A: Incident Prevention has answered this question before, but it won’t hurt to revisit it and use the opportunity to explain how OSHA analyzes a scenario to see if it’s a violation. Most objections to operating a hot-line clamp (HLC) under load are based on OSHA 29 CFR 1910.269(l)(12)(i), which states that the “employer shall ensure that devices used by employees to open circuits under load conditions are designed to interrupt the current involved.” There are some utilities that prohibit operating HLCs energized, and there’s nothing wrong with that. Our purpose at iP is not to judge an employer’s operational rules but to enlighten and educate the industry.

On its face, the rule seems to prohibit use of an HLC to break load. Anybody could also argue, then, that any operation of an HLC must be dead-break since HLC manufacturers offer no load-break value at all. However, there are several facets to analyze in this scenario. First, if a non-rated HLC cannot be lifted under load, how about a drop-out switch? We operate those thousands of times a day without injury to the employee, although sometimes an ill-advised operation does smoke a pole top. There is nothing in the rules that prohibits an employer from making an engineering-based decision establishing criteria or protocols for operating HLCs or drop-outs under certain load conditions. Primarily, the employer’s determination would be based on risk to the employee and risk to the equipment. For OSHA, the primary consideration would be risk to the employee. Just as in the working alone rule, if the device is operated by a hot stick from a position that prevented injury to the employee, there would be no violation. Second, what would be the solution in the scenario? If the solution required installing a mechanical jumper and installing a load-break switch, would such an operation add risk exposure to the crew, and would adding the switch really enhance the safety of the operation? At the very worst case, the scenario – operating the HLC under load – could be ruled a de minimis violation. De minimis is the level of violation where OSHA recognizes that a direct rule was violated, but there was no other way, or no safer way, of executing the required task, and there was no risk to the employee.

Football season is here, and hunting season is right around the corner. That means it’s also outage season for the electric power industry.

Planned outages allow utilities to take equipment out of service for maintenance, replacement or new construction. The timing is dictated by the utility owners and the regional transmission organizations that oversee the power grid. Planned outages can last from 15 minutes to months, and they can be continuous or intermittent. Most occur late in the year because loads are lower than during the peak summer and winter months. In addition, utilities need to use up their capital budgets for the year.

The height of outage season is between Thanksgiving in the U.S. and Christmas. With the rush to perform outages as quickly as possible, they often entail 12- to 16-hour workdays and seven-day workweeks for crews. Given the pace and intensity, along with the weather conditions, the potential for injuries is significant. To combat these risks, following are a number of best practices that can be used in your organization to help keep crews safe during outage season.

Site-Specific Safety Plan
Safely performing an outage begins with the crew developing a comprehensive, site-specific safety plan that – at a minimum – addresses manpower, equipment, logistics, training and emergency response. Because planning for most outages takes months, there’s plenty of time to thoroughly address safety.

Manpower
When developing the safety plan, establish how many workers will be needed to perform tasks safely and efficiently. In particular, consider work hours, because expecting workers to put in too many hours increases the risk of something going wrong on the job. Do you need 10 employees to perform 16-hour shifts seven days a week, or is it more prudent to ask 20 employees to work 10-hour shifts for five days?

Culture is one of the most significant drivers of an organization’s safety performance. It can take time to build a safety culture, and it also takes time for employees to assimilate into an existing culture after beginning work for an organization. This poses a serious challenge for organizations that regularly scale to meet project demands. An influx of short-service employees (SSEs) often coincides with an increase in incidents. While there are a number of reasons for this – such as poor hazard recognition – one significant reason is that SSEs have not yet assimilated into the existing culture’s standards of safe operations. Despite efforts to overcome this problem, many companies continue to report that it remains one of their greatest challenges. After examining SSE programs implemented by different organizations, my colleagues at The RAD Group and I have identified criteria for an SSE program that helps new employees more effectively adapt to a company’s safety culture.

The Root of the Problem
Once a strong culture is in place, it is like a hidden force guiding people’s decisions to work safely. However, it takes time for people to fall under the influence of a safety culture, and in the meantime they may work in a way that does not align with their employer’s standards. The root of the problem, of course, is that SSEs by definition have not been in the organization long.

To better understand and respond to this enduring challenge, it helps to address three questions:
1. How do people assimilate into a culture?
2. Why do some SSE programs fall short?
3. What kind of program would more effectively assimilate SSEs into a safety culture?

There are hundreds of thousands of man-accessible vaults in North America, with potentially tens of thousands of utility worker entries into those vaults each year. And it’s likely that every worker who enters a vault appreciates the safety procedures that govern the work. The combination of high-voltage electrical cables and aging infrastructure can exponentially complicate even the most routine vault-related task. In addition, many utilities across North America continue to report electrical vault failures, some of which lead to violent explosions.

For the most part, utility owners have a good understanding of the risks of entering man-accessible vaults and conducting work inside of them. There are many stories and equally as many opinions as to the safety and stability of the underground electrical network. The intent of this article is to summarize some known conditions your employees may face during execution of work in underground vaults. Although explosions may constitute the bulk of catastrophic events, thorough consideration of all hazards should be included in risk analyses.

The Vault
There is no uniform standard pertaining to vault configurations, but utilities regularly have an engineering standard. Man-accessible spaces can be as shallow as 8 feet deep with 340 cubic feet to approximately 30 feet deep with 3,000 cubic feet. Each vault is connected to others in the underground system through ducts and can have one to several high-voltage cable circuits passing through it. Some cables pass through directly while others contain splices, connections, transitions and some high-voltage switchgear or similar equipment. Most common cables are cross-linked polyethylene – often referred to as XLPE – or lead cable circuits. There is the potential for other systems to be present in spaces associated with lower voltages and communication cables. Some vaults have standard manhole lids while others have latch plates. The number of combinations is endless, but hazard exposure in these spaces is similar and can be categorized into exposure tables. When conducting your risk assessments, it is generally accepted in most jurisdictions to group your spaces by similar configurations of space and type. This will help organize information, reduce the volume of documentation and provide your field crews with clear data to safely perform their work.

Utility personnel are going to find themselves in confrontations with dogs. It is the nature of our work. How a worker responds during that type of engagement will have consequences that can be good or bad. The best consequence is when the parties go their separate ways and no one is left bleeding. Frankly, bleeding is not the worst outcome of these situations. People sometimes die as a result of confrontations with dogs, and the dogs can be hurt or killed, too. As a dog person, I would choose to see everyone walk away if at all possible.

While there is no magic formula that can be used to prevent you and your employees from being attacked by dogs, there are many good training programs out there and many good companies that provide dog attack prevention training. I have witnessed many training sessions and one thing is certain, not all of them provide the same information or approach. A few years ago I decided to perform some research on my own and compare it to what I knew about dogs as a longtime dog owner, a former dog breeder, and someone who is experienced with trained canine service members in the military and on police duty. I should also mention that some of my experience comes from four or five up-close engagements with big, seriously aggravated dogs in the backyards and pastures of utility customers. I can assure you that the nature of those incidents squared well with what I have learned over the years.

Now I must offer this disclaimer: Dogs can’t read. They don’t have the benefit of the wisdom offered throughout this two-part article (check out part two in the December 2016 issue of Incident Prevention). No one can account for or predict every dog’s response. What you read during the course of both of these articles will help you understand, in part, why dogs do what they do. You may also find some practical ways you can improve your chances of having safe experiences with dogs, both those that are friendly and those that are not so friendly.

In the 2014 OSHA update to 29 CFR 1910.269 and 1926 Subpart V, major changes were made regarding apparel and minimum approach distance (MAD) calculations. And yet I believe the agency missed an opportunity related to distribution voltages and gloving of energized conductors and equipment. For all intents and purposes, other than the MAD updates, few changes occurred in 29 CFR 1910.269(l) regarding working position. A new requirement removed any implied obligation that an employer is accountable for ensuring employees do not approach or take any conductive objects within the MADs found in tables 6 to 10 of 1910.269. The standard now clearly and without any doubt requires an employer to calculate and provide MADs to all employees and contractors working on energized systems.

Paragraph 1910.269(l)(3)(i) now states that the “employer shall establish minimum approach distances no less than the distances computed by Table R-3 for ac systems or Table R-8 for dc systems.” And the updated standard also now requires an engineering analysis on voltages greater than 72.5 kV to allow for transient overvoltages that occur due to system operations, breakers, capacitors or lightning. Ironically, the MAD found in the 2002 National Electrical Safety Code for 25-kV systems was 31 inches, 12 years before it was changed in OSHA’s update to 1910.269.

Q: What is meant by the phrase “circulating current” as it pertains to transmission towers? Does it have something to do with the fact that there is no neutral?

A: We’re glad you asked the question because it gives us an opportunity to discuss one of the basic principles of the hazard of induction. More and more trainers are teaching with a focus on principles instead of procedures, and we often overlook some of these basic definitions. The concept of circulation is associated with what happens in any interconnected electrical system. Refer to the basic definition for parallel paths: Current flows in every available path inversely proportional to the resistance of the path. That means that current flows through every path, and the path with the least resistance has the most current flowing in it. Inversely, the path with the most resistance has the least current flowing in it.

When you ground a circuit to the structure, you are making an electrical connection to the tower. Current will flow in every available path. If there is any source for current, including induction, there will be current flow. The greater part of the current will flow in the lower-resistance pathways. If the tower is well grounded, the majority of the current will flow in the tower to ground. In a distribution system, the majority of the neutral current flows in the neutral. Pole bonds to ground rods have much higher resistance and therefore lower current that usually can’t be measured by a typical clamp current meter, so some people think there is no current flowing in them. There is, and under the right conditions – such as a fault or open in the neutral – the level of current flowing in a pole bond can be deadly.

It’s 3 a.m. Once again the dull ache stirs you from sleep. The first time was at midnight. Now the ache in your shoulder is telling you it’s time to roll onto your other side. Hopefully this will be the last time this happens tonight.

For far too many lineworkers, this has become a nightly ritual. In 2004, Business Health Resources conducted a symptom survey of 224 overhead electric employees who worked for one public utility, and it revealed that 56 percent of them experienced shoulder pain a couple times a week or more often. Many experienced shoulder pain on a daily basis. Because shoulder problems are so common, most lineworkers have come to believe they are just part of the job. Are they really, or can they be prevented?

Shoulder conditions can occur as a result of acute trauma injuries like falls or car accidents, or they can occur from cumulative trauma, which is the slow wear and tear that takes place over time, usually due to performing repetitive and physically demanding tasks using stressful working postures. The problem with cumulative trauma is that as the damage accumulates, you always feel pretty good – right up to the moment you are in pain. It’s a sneaky problem.

To understand what leads to cumulative trauma, we first need to cover some basic anatomy of the shoulder joint. It is a loose ball-and-socket joint, making it highly mobile so we can put our hands wherever they are needed. The price we pay for all of this mobility, however, is a loss of structural stability.

If you place your fingers on top of your shoulder, the bony little lump you feel is the acromioclavicular – or AC – joint, which is the joint between the collarbone and your shoulder blade. It is the only bone-to-bone connection between your arm and the rest of your body. The AC joint is about the size of the joint at the base of your thumb, and yet it has to safely transmit all of the stresses from your arms to the rest of your body. This design makes the shoulder far more susceptible to wear-and-tear injuries, especially when it is subjected to abnormal stresses, like those that come from performing line work using stressful techniques.

Monday mornings at Coutts Bros. – an electrical line construction and maintenance contractor – begin the same way they have for more than 50 years. The crew meets on the old Coutts family property in Randolph, Maine, before 6 a.m., coffee and lunchboxes in hand, wearing shirts and hats that sport a variety of company logos from the last few decades. Conversations are lighthearted; depending on the season, discussions range from the weekend’s Red Sox, Bruins or Patriots game to embellished fishing and hunting stories, complete with cellphone pictures to prove the tales are mostly true.

This family atmosphere has been at the heart of the company since it was incorporated in 1963 by the first generation of Coutts brothers, Stan and Bill, who initially ran the business out of their family barn – which is still in use as a garage – using a John Deere tractor. The company got their first taste of utility work when the brothers began using the tractor to haul, dig and set poles for the local power company. Eventually the tractor was upgraded to a bulldozer, and today Coutts Bros. manages a fleet of excavators, bucket trucks and assorted equipment used for utility maintenance and construction projects.

Safety Program Evolution
Throughout the years Coutts Bros. has been in business, their processes have evolved considerably, primarily with regard to safety. Those early morning conversations are cut short when a crew member sees that the clock has struck 6 a.m. – this means it’s time to stretch. “Chin tuck!” is shouted from inside the garage, and 30 heads drop with a thumb to their chins. The stretching program is one of many safety initiatives that Coutts Bros. launched three years ago as part of a comprehensive safety-focused effort.

This is the final installment in a four-part series on trenching and excavation. “Trenching by the Numbers” (http://incident-prevention.com/ip-articles/trenching-by-the-numbers), the first article in the series, presented a simple method for recalling OSHA’s trenching and excavation requirements. The second article focused on soil mechanics (http://incident-prevention.com/ip-articles/soil-mechanics-in-the-excavation-environment), taking an in-depth look at the behavior and characteristics of different soil types and their relationships with water and air. In the June 2016 issue of Incident Prevention, I covered “Protective Systems for Trenching and Excavations” (http://incident-prevention.com/ip-articles/protective-systems-for-trenching-and-excavations). To close out the series, I will present techniques for creating a safer, more productive trenching environment, and then provide some food for thought about how to sell these techniques to management.

Dewatering Using Well Points
It’s no secret that water can greatly contribute to the success or failure of any trenching and excavation activity. OSHA requires that employers take steps to keep workers from being exposed to standing water conditions. One of the more proactive approaches to dewatering a site is to install well points. A hole is augured into the ground, and a perforated pipe is inserted into it. Then, a submersible pump is placed inside the pipe. This technique can be especially effective in sandy soils.

However, there are two caveats to keep in mind with this technique. First, it works best when performed three to five days before excavating begins. This is because water is self-leveling; thus, when a void is created by the pump, the water in nearby soil leeches into the work area. If excavation activity takes place too soon after the well point is installed, one could misguidedly conclude that well points make conditions worse when, in reality, poor planning and a misunderstanding of the process are to blame.

Incident Prevention has been covering personal protective grounding (PPG) for many years. Most of the emphasis has been on overhead applications for transmission and distribution. Lately, however, iP and many consultants associated with the publication have been receiving more and more inquiries from utilities seeking to understand the issues related to PPG applications in underground.

Part of the issue with PPG is that, as I mentioned, most training and rules seem to coalesce around overhead applications. The majority of the written standards – both OSHA and consensus – are found in sections dealing with overhead scenarios. It’s anecdotal, but it seems that most of the injuries or accidents discussed in the industry are also related to overhead. Still, the OSHA standard has requirements for PPG that do not specify or exempt underground applications, such as 29 CFR 1910.269(n), “Grounding for the protection of employees.” Employers have recognized that the risks we are discovering related to current flowing in grounded systems exist in underground, too. As responsible employers, they are seeking information, and not all of the information out there is good.

When OSHA updated 29 CFR 1910.269 and merged almost all of its requirements with 1926 Subpart V, the requirement to protect employees from step potential was enhanced. In the months following the publication of the final rule, this change was rarely mentioned in the major webinars conducted by several prominent utility industry groups, so I want to take this opportunity to cover what you need to know.

First, let’s talk a bit about the basic fundamentals of Ohm’s law and Kirchoff’s law of current division in order to ensure you understand the seriousness of step potential hazards. Ohm’s law states that electricity will take any and all conductive paths, and Kirchoff’s law of current division states that the amount of current flow is dependent on the resistance and impedance in the current path.

As I travel around and conduct training, I find that many electric utility employees – much like me in the 1970s – do not understand these and other basic laws of physics that determine the number of hazards we face. The human body is not much more than a 1,000-ohm resistor when put into an electrical circuit. If a human body is placed in an electrical path/circuit, the amount of electricity that enters the body is about 50 volts AC. During this type of occurrence, the soles of normal work boots and shoes will provide an employee a small amount of protection, but if the employee were to kneel down and touch a vehicle grounded to a system neutral, or place a hand on a grounded object, the amount of protection would be significantly reduced.

Q: We have heard that OSHA can cite an employer for violation of their own safety rules. How does that work?

A: OSHA’s charge under the Occupational Safety and Health Act is the protection of employees in the workplace. The agency’s methodology has always assumed the employer knows – or should know – the hazards associated with the work being performed in the employer’s workplace because that work is the specialty of the employer.

OSHA’s legal authority to use the employer’s own safety rules as a reason to cite the employer is found in CPL 02-00-159, the Field Operations Manual (FOM), which is published by the agency for compliance officers (see www.osha.gov/OshDoc/Directive_pdf/CPL_02-00-159.pdf). The explanation is in the FOM section about the elements required for a citation under the General Duty Clause, in particular Chapter 4, Part III, Section B, Entry 6(a). This part covers the required element of employer recognition. If there was no reasonable expectation that the employer could recognize the hazard to the employee, the employer cannot be cited for a violation. The FOM specifically states that employer awareness of a hazard “may also be demonstrated by a review of company memorandums, safety work rules that specifically identify a hazard, operations manuals, standard operating procedures, and collective bargaining agreements. In addition, prior accidents/incidents, near misses known to the employer, injury and illness reports, or workers' compensation data, may also show employer knowledge of a hazard.”

Several years ago, when I was serving as chief investigator for the NIOSH-funded Missouri Occupational Fatality Assessment and Control Evaluation Program, I was called to a scene where a 39-year-old journeyman lineman had been electrocuted while working for an electrical contractor. At the time of the incident, the lineman, his co-worker and the foreman had been working at an electrical substation. The city that owned the substation was in the process of switching their electrical service from a three-phase 4-kV system to a 12-kV system. There were several feeders on the structure, but only one was energized to provide service to the city. The lineman and his co-worker were on the steel framework of the substation when the lineman proceeded to work his way over to the incident point. He sat down on the structure next to the energized feeder and energized lightning arrestor and began to climb down the steel latticework. Typically the contractors accessed the structure with a ladder, but for one reason or another, the lineman chose to climb down using the corner latticework of the structure. At that point, the lineman contacted the energized arrestor with his forearm. His co-workers responded immediately and began CPR, and emergency personnel were summoned to the scene. Unfortunately, the lineman did not survive.

Despite our best efforts to protect workers in the field, incidents like these still occur and, as a result, you may find yourself leading an incident investigation. One of the primary goals of any investigation is to find out exactly what happened so that future occurrences can be prevented. With that in mind, I put together the following 10 tips designed to help you obtain quality information about each incident you investigate, put your interview subjects at ease, and determine an accurate account of what occurred before, during and immediately after each incident.

This is the third installment of a four-part series on trenching principles. “Trenching by the Numbers” (http://incident-prevention.com/ip-articles/trenching-by-the-numbers), the first article in the series, presented a simple method for recalling OSHA’s trenching and excavation requirements. The second article focused on soil mechanics (http://incident-prevention.com/ip-articles/soil-mechanics-in-the-excavation-environment), taking an in-depth look at the behavior and characteristics of different soil types and their relationships with water and air. In this article, we will discuss the four different protective systems described in OSHA 29 CFR 1926 Subpart P, “Excavations”: engineered design, timber shoring, shield systems, and sloping and benching. Each system has its own unique strengths and weaknesses. Thus, depending on the environment and the circumstances of the work to be done, one system may be a better fit than the others. Let’s take a closer look at all four systems.

Engineered Design
Engineer-designed protective systems typically are not used in utility operations. Instead, this type of system is more likely to be seen on large-scale building foundation work, and it may also be used on complex construction projects, such as around waterways. In any case, some activities – like those that involve deep, poured-in-place vaults or occasions when a duct bank has to pass beneath water and sewer – may benefit from an engineer-designed system customized for the situation. The need for engineered design may be rare, but knowing what it is and why it is used is necessary information for project and safety planners.

On your way to work today, how many dashed lines in the middle of the road did you pass? What ornaments decorate your dentist’s office? How many people wearing glasses did you see last month?

If you’re like most people, you don’t know the answers to these questions, and that’s a good thing. In his book “The Organized Mind: Thinking Straight in the Age of Information Overload,” author Daniel J. Levitin states that the processing capacity of the conscious mind is estimated to be about 120 bits per second, barely enough to listen to two people talking to you at the same time, yet in our waking lives most of us are exposed to more than 11 million bits of information per second, according to Leonard Mlodinow’s “Subliminal: How Your Unconscious Mind Rules Your Behavior.” Without what psychologists call an attentional filter, we’d be able to recall the minutiae around us, but left without the mental capacity to draw reasonable conclusions about what we perceive, and therefore left without the ability to lead normal lives.

The problem with an attentional filter, however, is that it occurs on the subconscious level. Our brains decide what we notice without any conscious input from us. Of course, we can always force ourselves to notice small details by applying mental resources to count and memorize them, but that only happens with concerted effort.

In a utility setting, our attentional filter can create a conflict between what we do perceive and what we should perceive. Fortunately, the utility industry has an effective solution to our cognitive limitations: the job brief.