Fleet Profiles

Pandemic preparation is nothing new. In fact, I have been telling employers since the 1980s that a pandemic plan is one of the business/safety mechanisms they should have in place. It’s just good practice to address and interrupt a contagion that could potentially immobilize the employer’s workforce.

The United States has been researching pandemic responses since a swine flu outbreak in 1976, but few if any publications back then addressed workforce contagions. The earliest literature on organized pandemic responses appeared around 1976 when the U.S. government established formal research panels to develop a nationwide response to a pandemic threat. The panels performed research and modeling activities and revised and expanded both research and national immunization programs in response to new threats, such as the avian flu in 1997, anthrax in 2001 and SARS in 2003. Even though U.S. government literature mentioned bioterror as a concern following the avian flu outbreak, the anthrax event was a homegrown bioterror event that raised the stakes.

But first, this public service announcement.

If your organization doesn’t already have a policy on energy drinks, you should do the research and develop one. I had long been skeptical of energy drinks because I know that anything that artificially enhances body function always comes with consequences, especially if it’s overused. It’s no different than any prescription drug that supplants the body’s failed functions. There are always side effects. With heat stress or any other kind of stress, the body gets tired, which is how it tells you that it’s exhausted and needs rest to repair itself. If we artificially stimulate the body to ignore those signals, the outcome is not just bad – it can and has become deadly.

In the years of the energy drink boom, I was a contractor. On two occasions, I had healthy 20-somethings helicoptered to hospitals from remote areas after they collapsed and displayed symptoms of a heart attack or stroke. Both instances occurred in over 100-degree work environments. On each occasion, at the paramedics’ request, we looked for and found a cooler full of energy drinks. The victims couldn’t answer questions, but the paramedics had already seen the symptoms and needed to know if that was what they were dealing with.

This installment of “Focus on Fleet Safety” is a little bit different than usual in that we are going to write an operating safety policy. There are two goals here: to help you learn to develop policies that make a difference, and to prevent wrecked all-terrain vehicles (ATVs) and utility task vehicles (UTVs) on your job sites.

Over the last few decades, ATVs and UTVs have taken on a significant role in remote site access and large yard transportation. What have also occurred over the last few decades are serious and occasionally fatal injuries from the operation of ATVs and UTVs. In my own experience as a former transmission line contractor, we only had a few incidents with UTVs, but it was on every job where we used them. In my time since, I have received calls every year regarding incidents related to UTVs. They are probably involved more often because ATVs are not as useful on rights-of-way as they are in yards where managers employ them to get around more efficiently. In this article, we are going to discuss the elements of an ATV/UTV policy designed to address the most common issues related to ATV/UTV wrecks and how they can be prevented.

I’ve met a lot of people over the years while working in the utility industry. One of those people is in management with a respected manufacturer of aerial devices. Back when OSHA published 29 CFR 1926 Subpart CC, “Cranes and Derricks in Construction,” he and I and a few others were discussing how a utility operation could best comply with some of the standard’s requirements. The OSHA rules were formed with the perspective of typical construction sites in mind. In particular, we discussed the rule’s expectation that the site’s general manager will tell the crane operator about underground obstructions that might collapse and cause a crane to become unstable. It’s obvious that a crane operator setting structures on a right-of-way doesn’t have that luxury, so we were thinking about things we could do. The discussion landed on auxiliary outrigger pads. At the time, my friend from the aerial device company had this to say: “We have occasionally been sued by folks who turned over one of our cranes or aerial devices, but we have never been sued by anyone who had set up on auxiliary pads.”

I don’t know if that’s still the case with that company, but at the time I began to research why auxiliary pads appeared to be an important part of stable setup for aerial devices. Basically, it’s because sometimes even a few square inches of additional pad dimension can increase ground support by tons per square foot. When it comes to the four-point support of an aerial device that weighs in at tons, tons-per-square-foot increases are a good thing.

Are you concerned about cellular antennas? Decades of research on cellphones and cancer have not found a link between the two, but that hasn’t stopped some communities from creating laws and public service campaigns regarding protection of the public from cellular system threats. What these actions have done is created a sense that the risk exists, leading to much concern and confusion for the public. There are risks, and they are not to be ignored, but many of them are misunderstood.

As communications technology continues to develop, its next iteration – 5G – is already here. The idea of 5G is better coverage using smaller, low-power, overlapping range with multiple antennas. This is the same technology used in large offices and hospitals to overcome the cellphone signal shielding caused by buildings. The buildings have numerous low-power, overlapping antennas that ensure cellular signal communications. The communications industry needs more mounting locations, and utility poles are the obvious answer. 5G is more of a physical hazard than a radio frequency (RF) hazard because it includes a powered cabinet on the pole wired to the antenna above, creating more congestion on the structure for climbers. I receive lots of questions and rightly so because line personnel are finding themselves looking at antenna installations where they have never seen them before. 5G is very low energy compared to other RF emitters but should not be ignored. Most of the 5G hazard is the antenna at the top of the pole, which can be anything from a 30-foot light pole to a 60-foot transmission pole. The obvious precaution, as with any antenna, is to not put yourself in the antenna beam. So, a 360-degree 5G antenna is like any 360-degree antenna: Don’t put your body in the beam.

I perform audits of both utilities and contractors. When I work with them to do those audits, we include trucks and trailers. The trailers I’m talking about here are not the box vans behind tractors, but the general-duty trailers used to haul trenchers, backhoes, wire reels and padmount transformers. It’s no surprise that the trailer issues we discover are in keeping with the types and frequencies of violations that enforcement officials find on the roadways: those involving lights, load securement and brakes. Auditors also get a lot of questions about trailer safety, or more specifically, trailer rules, which are in place for trailer safety. I almost always receive those questions after an enforcement action has occurred.

Many enforcement actions have come about due to the efforts of states that have noticed trends in trailer-related incidents. The incidents didn’t involve semi-trailers pulled by tractors; they involved smaller trailers used in commercial environments where enforcement had not spent much focus. Without that focus, there was a lack of accountability, and now it’s caught up with us. States are enhancing their observations of commercial trailering, making stops and taking trailers out of service for numerous issues, most often related to brakes.

The inspiration for this article was a recent training visit I made to a central U.S. utility. On the way to the training location, I saw a utility crew on the side of the road with a state trooper. It turned out they were my training class for that day, so I got to ask them about the stop. It was about brakes. The trooper was getting ready to pull out from a doughnut shop (really, he was) when the crew passed in front of him. The trooper noticed the lack of a battery box and a battery, so he stopped them. He didn’t check to see whether the brakes were working because the lack of a battery on the electric braking system meant the breakaway emergency system wasn’t functional. The crew got a ticket, but they also caught a break. Since the yard was two blocks away, the state trooper allowed the crew to continue to the yard instead of putting them out of service. He also stopped by later that afternoon to see if the trailer brakes had been repaired. They had been.

This is a review of ANSI/SAIA A92.2-2015, “American National Standard for Vehicle-Mounted Elevating and Rotating Aerial Devices.” As a consultant, investigator and auditor, I have been surprised time and again that people who should know this standard do not know it that well. Most fleet managers are familiar with the rules, which is important because the A92.2 standard obligates owners of aerial lifts to be held liable for equipment they sell in certain scenarios. On the employee side, a working knowledge of A92.2 can prevent incidents and loss of life. In fact, a recent live-line barehand training class was what inspired this topic. We found that a bucket truck had the leasing company’s logo sticker adhered down both sides of the insulated boom section. That bucket truck was designed and rated for barehand use at 500 kV, yet a vinyl-plastic printed logo installed by the leasing company, spanning two-thirds of the insulated length, could have had some serious implications for the safety of that boom.

In this article, we are going to review some of the information covered in the A92.2 standard. Readers should recognize that ANSI/SAIA consensus standards are protected by copyright, so we will not directly reproduce the text of the standard itself. The A92.2 standard can be purchased directly from the ANSI website (https://webstore.ansi.org).

Recently I have received numerous emails and phone calls regarding respiratory air-filtering masks rated for arc flash. I’m sure everyone reading this, no matter what country you’re in, is aware why that’s the case: the COVID-19 pandemic.

If you are a regular reader, you know it is my methodology to address topics by first citing the related safety standards in effect and then discussing the issue from a practical perspective typically related to the utility industry. This time is no different – for the most part.

Initially, the use of masks during the pandemic was limited as effective respiratory protection and still is for the public per the Centers for Disease Control and Prevention. As far as OSHA was concerned regarding workplaces, the only approved mask was the NIOSH-approved N95 filtering facepiece respirator (FFR). The N95 rating means that the mask meets the criteria for effective filtering of airborne particulates and moisture at 95%. The rating system also was established by NIOSH. It is important to understand that the N95 rating is based on the assumption that the masks are utilized by trained users meeting the OSHA respiratory protection worker training and fit-testing standard, which also can require a medical evaluation of the user.

Across our industry, I have found all kinds of policies for grounding trucks. I also have found that in many cases, employers’ rules for grounding trucks are not based on OSHA requirements and – even more concerning – are not based on sound principles of protection. I believe the grounding policies are well intentioned, but they fail to achieve two important goals: (1) meeting the OSHA standard and (2) protecting workers where electrical contact hazards exist. So, let’s take an ABCs approach to the issue because even though some detailed explanation is required, it really is that simple.

A Defensible Plan
You must be able to defend your plan or policy. This is the case for every plan or policy. Defense is built around establishing and accomplishing a goal, understanding the hazard, understanding the mitigation of the hazard, training at-risk employees, and conducting periodic audits to ensure the plan or policy is properly employed.

The Goal
In our case, the goal is protecting workers from electrical hazards created by contact with mobile equipment. Let’s agree here that mobile equipment is anything that is moved into a work site. In addition, it is mobile equipment that can become energized. If it can’t become energized, it is not a hazard.

Understanding the Hazard
The hazard is energizing mobile equipment and the transfer of hazardous energy to an employee who is on, in contact with or near the equipment that has become energized. The hazard involves unintended or inadvertent energizing. There can be several energizing sources, but we can classify them as follows: direct contact with an energized source, capacitive coupled voltage or inductive coupled current (I’ll explain this a little later), and inadvertent energizing by grounding to a current-carrying source. Let’s start with this one first.

When analysts look at utilities, and to some extent utility contractors, they often see what’s referred to as “mission creep.” That occurs when the expertise of the utility should be focused on quality and continuity of service but begins to be compromised by focus on too many other areas. The opposite of mission creep is when business elements that are critical to successful progress toward the goal get overlooked because of focus on the goal. One business element that gets less attention than it deserves are big trucks and the Federal Motor Carrier Safety Regulations (FMCSR). Granted, 75% or more of the FMCSR do not apply to utilities, and many parts that do apply are difficult to implement. Implementation is tough because, even as employers with drivers and big trucks, we are not carriers, which is the target audience of the rules, but we still are regulated by those carrier-related standards. The key areas of compliance for utilities are driver qualification, record of duty status (RODS), safety equipment and load securement. There also are a couple of new initiatives that we should keep an eye on.

A number of years ago, I went to a construction job site to participate in the morning crew meeting tailboard. The construction project was a 90-mile double-circuit transmission pull. The new circuit was being constructed in an existing transmission line right-of-way that had two existing energized 345-kV circuits running parallel to the new circuit construction. The location where we met was a pulling site. Crews had already been pulling at the location for two days. The work that had been completed the day before left conductors pulled in about halfway. Both ends had been caught off with chain hoists overnight so that the conductor was still under tension on the tensioner near the location of our meeting. The conductors at the tensioner had been temporarily grounded to a driven ground rod for the protection of the lineworkers. Red barricade tape also was completely encircling the tensioner, the reel trailer and the 30-ton crane hooked to the reel trailer.

I was standing near the back of the assembled group of about 20 personnel, listening to the site superintendent who was conducting the safety topic on grounding for protection from induced voltages. While he spoke, I noticed movement some 100 yards past him at the front of the 30-ton crane that was anchoring the reel trailer and tensioner. It was a fleet mechanic. He was working on an oil leak, which is one of the things mechanics do. The problem was that while the mechanic was conducting that repair task, he was in a position that exposed him to electrocution. The mechanic was there working with the full knowledge of the superintendent who was delivering the safety talk. But while the superintendent spoke to the crews about isolation, grounding and the hazards of induction, the mechanic was doing exactly what the site superintendent was telling the line crews not to do.

The date was January 28, 1986. The event was the tenth and final flight of the Space Shuttle Challenger. Seventy-three seconds into flight, the booster rocket that was lifting Challenger into space exploded, killing all seven astronauts aboard.

When events like the Challenger explosion happen, you never forget where you were at the time. You remember the iconic photos and the national days of mourning for those lost. After the Challenger explosion, President Reagan appointed the Rogers Commission to investigate the disaster, and some of you may remember the news commentary on the Rogers Commission Report. If you didn’t study the reports from the incident, you likely aren’t aware of the stunning findings, the changes that were called for and, even more importantly, the effect the changes at NASA have had on industry – including the utility industry. It’s worth taking a look. You can read about lessons learned from the incident at https://ocw.mit.edu/courses/aeronautics-and-astronautics/16-891j-space-policy-seminar-spring-2003/readings/challengerlessons.pdf.

The occupational safety and health industry and civil authorities require that employers provide training to employees. In the U.S., OSHA mandates safety training related to tasks assigned to employees. The agency often also requires the employer to certify that the training has been completed. In fact, if you have an incident requiring OSHA notification, the first question that will be asked is, “Was the employee trained for the task?” The second inquiry will be a request for documentation of the training, usually followed by an enforceable subpoena for those training records.

Training and certification of training are important for two reasons. The first is that training has clearly been demonstrated to reduce incidents and injuries to workers. Second, OSHA will hold employers accountable for the training they conduct. The penalties for willful violation of training requirements are rarely discussed, and I hesitate to do it here, but the record shows that if an employer does not train, and OSHA can show the employer knew training was required, the penalties are based on willful violation. Penalties for willful violations that result in fatalities can include jail time for the employer. In addition, if OSHA wins a willful violation case, the employer can expect charges of negligence under both civil and criminal liability standards. Don’t take this training responsibility lightly. I, like OSHA, would prefer employers be compliant for the welfare of the workforce because they are ethical and care about their employees. But if the threat of prosecution works, we still accomplish the desired outcome: a safer workplace.

Over the past few weeks I have received several inquiries regarding horizontal directional drilling (HDD). It’s not unusual in our industry for questions to make the rounds of utilities and contractors, generating interest and often controversy. I also have recently received several inquiries regarding OSHA allegedly canceling the digger derrick exemption in 29 CFR 1926 Subpart CC, “Cranes & Derricks in Construction.” OSHA hasn’t done that, but somebody said they did, and folks started asking around. Soon after, I received calls for clarification on the matter. In the digger derrick case, there was nothing to it; OSHA has not changed anything about the exemption. However, concerning HDD, there is an issue that raises an interesting question for those who administer compliance.

The point of the rest of this article is not to recommend or criticize any safety procedure associated with HDD. The point is to examine the role of manufacturer warnings and OSHA-compliant safety performance in the workplace. There is no doubt that I will get emails from HDD machine manufacturers and adherents of overshoe use, as well as overshoe sales or manufacturing representatives. I invite your response. To be clear, both Utility Fleet Professional magazine and I are solely interested in providing an opportunity for perspective and analysis of a process that will help individuals learn how to deal with challenges in the workplace.

If you’re reading this, it’s likely that you work in a fleet management role. Your mechanics and drivers don’t do line work, install phone lines, bury gas lines or dig up high-pressure water lines. But what if they service equipment in the vicinity of craft workers who do perform those tasks? Are they exposed to hazards not related to their direct responsibilities? If so, what is your responsibility as their manager? This article is about educating supervisors regarding hazard evaluation. Where your people work and the hazards they face while on the job are your responsibility. So, following is an example that demonstrates how OSHA’s expectations with regard to your responsibility to your employees may exceed the agency’s written rules in ways you may not be aware of.

There is an employer who is a transmission-distribution contractor; the business also has a telecommunications (telcom) division. The employer’s lineworkers must wear arc flash protective clothing required by OSHA, but as far as he knows, his telcom employees are not required by the OSHA rules to wear arc flash protective clothing. However, because of an incident involving some of his telcom employees, the employer became concerned. He wondered, why don’t telcom employees have to wear arc flash protective clothing, and should they be wearing it? Keep in mind that arc flash protective clothing is not the same thing as flame-resistant (FR) clothing. Welders, wrecker operators and traffic control professionals wear safety vests and bibs that are considered flame-resistant. Flame resistance is the quality of a material designed for protection from exposure to fire or flame, not electrical arcs. OSHA requires that arc flash protective clothing also must be flame resistant to ensure clothing does not continue to burn after exposure to an electrical arc. In addition, flame resistance is required for the outer layer of clothing worn by a worker who could be exposed to a heat source that could ignite that outer layer. There has been confusion over the years, so it is important to recognize that use of the term “FR” on a traffic vest label does not mean the vest is arc protective; it is only flame resistant. It’s a habit to use the term FR when referring to arc flash protective gear, but we all need to understand the difference in labeling.

There is probably not a fleet mechanic or fleet manager who has not heard something about grounds for trucks. But for all the talk about grounding trucks, including rules and commentary, there is very little consideration for how grounding connections are made to a vehicle. Unlike most every other procedure in the utility industry, there are no OSHA guidelines, consensus standards or best practices for connecting the truck to the truck ground. There are rules requiring grounding of trucks, but there are no best practices, procedures or methodologies for connecting grounds or ground attachments to trucks to allow grounding. So, that’s what we’re going to discuss in this installation of “Focus on Fleet Safety.”

For fleet managers to effectively facilitate the grounding of trucks, we need to understand the purpose of grounding and why it fails to do the job expected. Actually, the job expected often is the bigger issue because it may not be what you think. Grounding a truck does not directly protect workers from electrical shock, nor does it eliminate a shock hazard. Grounding trucks has one purpose: to cause immediate operation of a protective device. The protective device is the circuit breaker through which voltage and current are delivered to the electrical system. A truck is not an electrical conductor – it is a mechanical device, meaning that to ensure that current flow across the truck is sufficient to cause operation of the circuit protective device, an electrical connection must be employed to bypass the vehicle’s nonelectrical isolation from ground. Nonelectrical isolation refers to mechanical interfaces of bolted parts, the rubber tires and the outriggers on earth. Current has to pass these mechanical barriers to initiate circuit-breaker operation. In an electrical contact with a truck, the circuit breaker feeding the system in contact with the truck may not trip. As often happens, the circuit will continue to feed current into the vehicle, resulting in fire as well as a continuing electrical shock hazard to any person near the truck. So, the purpose of grounding is to create a good path for electrical current to flow. That good path causes a higher current to flow, resulting in fast tripping of the breaker feeding the electrical circuit. Fast tripping minimizes the damage to the electrical system and the truck.

We provide tools and equipment for our crews. Sometimes they are special tools, and sometimes they are generic tools necessary to support routine crew work. Sometimes they are accessories for trucks and equipment, and sometimes they are simply extra tools or equipment to make things easier on the people in the field. The question then is, are these tools approved?

The following is going to aggravate some readers, so let’s start with a reminder: I attempt to clarify and simplify compliance with this series. This is about making compliance easier and sometimes less expensive. So, here is an example.

A few years ago, I approved a transmission construction crew’s replacement of a 5/8-inch wire-rope winchline with a 7/8-inch synthetic winchline. The crew wanted to increase a safety margin for dropping poles down through energized circuits by eliminating the steel winchline from the energized environment. Fleet managers also approved the replacement and sent the new synthetic winchline to the worksite’s mechanic. The fleet mechanic had removed the wire rope from the crane to a wooden reel and was in the process of winding on the synthetic when the client’s safety managers stopped the work. Their company had a strict interpretation of “manufacturer-approved.” They required a like-for-like replacement unless the winchline was OSHA-approved.  The original wire rope was load-rated at 44,000 pounds. The mechanic showed the inspector that the new synthetic was rated higher at 57,000 pounds. It didn’t matter to the client because their rule was no modifications to the winchline without written approval from the manufacturer.

Every equipment manager’s budget is impacted by unexpected losses and repairs. If you manage equipment, you know this. You may expect to get 160,000 miles out of that crew truck or 2,000 hours out of a digger derrick before major component replacement, but that’s not going to happen if a line crew drops it off a mountain. I once witnessed the remains of a digger derrick that was lost while being winched up a mountainside for a wilderness construction project. It was unoccupied when the slings attaching it to the D8 crawler dozer failed. At the bottom of the mountain, the winch hook was the only recognizable part. A few years later, I had flashbacks when I heard our construction manager negotiating with our right-of-way clearing manager for the loan of one of their D9s to haul equipment up a mountain. My interest was safety. But in the process of planning for safety, we gained a valuable lesson in equipment preservation. I got involved with pre-planning for mobilization and learned how construction managers planned to perform the project. It was a new line. Right-of-way clearing was being done by another contractor. There were no roads, so access was the challenge. The terrain was very steep at a couple locations.

Prior to the start of the work, I conferred with fleet management. Tow rigging connections are an issue on most equipment. Digger derricks and bucket trucks sometimes come with bumper-mounted factory tow hooks. These bumper hooks are sufficient for getting equipment out of sand if it gets stuck, but they are not necessarily appropriate for a half-mile haul up newly cleared, soft terrain. Fleet asked the truck manufacturer about getting design parameters for the bumper and frame to come up with a modification for towing.

In the past few months, I have received comments and inquiries from all over the U.S. regarding what appears to be stepped-up enforcement of both load securement and vehicle weight. It’s not unusual that these topics garner attention from the U.S. Department of Transportation when it comes to carriers, but this recent uptick seems to be directed at smaller commercial vehicles as well as bucket trucks and digger derricks. There have not been any changes of note in the rules for vehicle weight and load securement; however, it appears that some latitude taken by utilities, if not given by the DOT, has caught the attention of those responsible for enforcement of the rules.

In the last couple of years, state enforcement agencies have used local media to inform local commercial businesses – that are not carriers – that they would be stopped if they did not appear to comply with loading and marking standards for their class of vehicles. In Arizona, New Mexico, Washington and Colorado, my colleagues and I began to hear of roadside stops involving lawn maintenance companies and small construction concerns that pulled trailers with loaders, backhoes and super lawn machines. That soon extended to power company trucks, especially those loaded with large wire reels. I even heard of one instance in which state enforcement set up scales in a shopping center parking lot on a well-known route out of a power company service center. Within 40 minutes they cited 22 vehicles for being overweight. You would think drivers would have warned others, but the DOT waved them into the parking area before they started weighing and inspecting the vehicles, so no one knew what to expect. It shouldn’t have been – but it was – a big surprise for that utility’s fleet management to learn what kinds of loads lineworkers were putting on those trailers.

Fleet management economics are not just about predictive scheduling, inspection and maintenance. Yes, you can predict and control operating costs by keeping and analyzing records. But one thing you can’t do is predict accidents, other than predicting you will have one at some point. However, accidents – especially expensive ones – don’t have to be an unpredictable liability. In fact, most accidents don’t have to happen at all, although sometimes we as managers enable them.

A few years ago, I got a call from the sheriff of a small town in Tennessee. I was working for a contractor at the time, and one of our trucks had been found on its side in the trees off a small two-lane road. The cab was crushed and our driver was deceased, his body trapped in the wreck for several hours. This was not just a matter of having to cut away the cab. The driver, who was not wearing a seat belt, had been thrown below the steering column in the crash. The cab folded in and around him, and the truck was a total loss.

The reason I chose this story to make the following points is due to how the incident played out within the organization. Everyone was devastated by the loss of the driver. That was expected. But after a few weeks, the incident became the focus of accounting, and that’s when the safety department came under scrutiny. That’s because the highway patrol had completed the incident investigation, and they discovered three enabling elements that – had any of them been changed – would have prevented the accident from occurring. The driver would not have died, the truck would not have been totaled and the financial loss would have been avoided.

These three elements won’t be common to all incidents, but I’ve detailed them here to demonstrate to readers that most incidents are avoidable. In addition, I’ve also identified some cultural initiatives that can prevent the enabling of future incidents.  

Element 1: The Route
The truck was a Freightliner twin-axle, 20-ton digger derrick. There were three main routes from the yard to the project site. It was 7:45 a.m., and the driver voiced concerns about traffic. According to his crewmates, he knew a faster route that was rarely used and would bypass the morning traffic. So, what was the value of the time saved? The incident investigation indicated the backroad route could have saved time only if the 35-mph speed limit was exceeded by 30 mph. The other two routes – an interstate and a four-lane highway – had fewer turns, fewer stops and speed limits of 55 to 65 mph. Perhaps more important was the construction of the roadways. In addition to having fewer turns, the two higher-speed highways had shoulders that varied from 26 inches at the narrowest to 96 inches at the widest. The shoulders became the most important issue because the rural road the driver had chosen had no shoulder. In several places, the road dropped off into rocky ruts just inches off the white line. The highway patrol’s analysis of the cause of the incident was that the right front wheel of the digger derrick dropped off the road into a rut, causing the driver to lose control of the vehicle.