On a recent construction site visit, I noticed a haul road for trucks right up
against the edge of an open excavation site. I pointed out the threat to those tagging
along, and they asked, "How far away from the edge should trucks stay?" I replied that,
with an adequate berm installed, it would be safe for the truckers and those in the
excavation. Both construction workers replied, "What's a berm?"
This article looks at the dangers of "working on the edge." We will review
threats we often overlook, the consequences of a safety professional not knowing what a
simple berm is (do you?), and sharing a few best practices and lessons that I have
learned from real experts.
Roadway Edges
As I walked on a project in Upstate New York with our
superintendent, he recounted a near hit that occurred over the weekend. No, it's not
a near miss; everyone gets that wrong. (George Carlin provides the best definition.) The
photos below show where a berm was needed and the correct berm we later built.
You can see the tracks left by a concrete truck as it rounded the
curve, dipping into and out of the trench. The site's response to what could have
been a fatality was inadequate at best because they
provided a reminder of a threat rather than its elimination. It is not an
uncommon approach in construction, but it is not the desired approach. When you
eliminate the threat, you eliminate the possible injury.
Work was stopped, a motor grader called up, and berms were built
to bounce vehicles back onto the roadway rather than tumble down the bank. How tall
should a berm be? The rule of thumb is the height of the tallest machine axle on the
project, which is simple guidance. The photo is a great example of how we corrected
this killing condition.
Figure 2: Tire Tracks Along EdgeFigure 3: Berm Along Edge
The following are some tips for the roadway edge during site work.
Look for any roadway drop off that could
roll any vehicle on your worksite. That includes culvert crossings.
If any drop-off is adjacent to any roadway, not just a haul road, install a
solid barrier/berm.
If trucks are backing up and dumping, install a berm before the edge so they
don't overtravel when preparing to dump their loads.
Whatever barriers are used, be sure they are built the entire length of the roadway. See below where an inadequate berm (too low) cost the driver his life.
Protective Edges
Water-filled plastic barriers have been a godsend to the
construction site when providing a protective edge to protect certain areas and the
public. When empty, they weigh about 300 pounds, but when filled, they weigh over
1,100 pounds. When I walk a project, I often check to see if they are filled. A
solid kick will let you know. And that's the problem—they are rarely filled.
There are few things more dangerous in our environment than
someone providing a false sense of security. Since filling them makes them harder to
move, many contractors don't fill the water barriers, so the wind, snowplows, and
drunk drivers move them with ease.
Figure 5: Empty Plastic BarriersFigure 6: Barriers Being Filled
The following are some tips on water-filled barriers for edges.
If you're using water-filled plastic Jersey barriers, make sure they are
filled with water. There would be no defense in a citation or lawsuit if they
are found empty after a construction accident.
The water line is easy to spot. In the photo showing one being filled, look for the arrow.
In the winter, add calcium to the water so it won't freeze. That makes them
heavier as well.
When fencing is attached and the water-filled barriers are empty, they can
move like chess pieces into traffic, float away, blow over, and injure people.
In addition, when water-filled barriers are empty, the warranty on their safe use is voided.
When using concrete Jersey barriers, the same holds true. They
must be on solid ground and secured to the ground with steel rods. I took the photo
of unsecured barriers in New York City. The photo shows barriers that were
unsecured, placed too close to the edge, and on melting frozen soil. Gravity was
standing by, waiting to cause an accident. Two full-time safety folks did not notice
the threat. After I pointed out the danger, work was stopped, and this temporary
roadway was closed. The barriers were then removed.
Figure 7: Unsecured Failing Edge Protection
Cranes and Edges
One of the most common contributors to any accident is gravity.
While walking a project, I witnessed a huge tracked Manitowoc crane working in the
distance. I could see it was not quite level and was working at the edge of an
excavation site. The site safety manager and I went over and asked the operator to
check the level of the crane. He yelled down that it was out of level by about 3
degrees. I asked him to step down to review the lift underway (concrete distribution
box), and that did not go well: He was angry. Questioning a crane operator can be
unsettling to the guy doing the asking.
We discussed the frozen ground that was thawing and my concern
that the crane looked a bit off. I took out my handy pocket level and placed it on
the frame, confirming the crane was out of level by 3 degrees. I then asked how
heavy the load was and if he had derated the crane
since it was not perfectly level. I explained that a crane off by 3 degrees can only
lift about 50 percent of what was intended. He asked, "What's derating?" As we
worked on replacing the crane operator, the safety manager asked, "How much weight
does it take to tip over a crane like this?" I answered, "One pound. One pound too
much."
The photo below confirms crane operators and contractors often
overlook two things when working along the edge of something that may fail—gravity
and future conditions. In the case shown in the
photo, we stopped using this crane until a remedy could be designed. This crane was
atop a large rise built specifically (and shoddily by the general contractor) for a
crane pad for lifting steel.
Figure 8: Poor Crane Placement
Erosion of Supporting Surface Beneath the Support
Cranes are often just on the site for a day. Planning for those types of
"picks" is rare. Field conditions may not be suitable, but the crane is there,
so the site team often gets to the point of "it's good enough." These photos are
a few examples of near hits from cranes that were only working for a day. What
is always surprising is the site managers were comfortable with these
conditions; I was not.
Besides a solid surface for the crane to stand on, there is also a need to
distance the weight and its load of the crane from the edge of an excavation
site. In the clay soil photo, you can see that if the excavator swings to the
left too far then an accident will occur. But really, that's no accident; he is
too close to the edge.
Let's say the excavation is 10 feet deep (where I took the photograph). That
would require the outriggers to be 15 feet away from the edge. Otherwise, the
weight of the crane and any load would surcharge the edge of the excavation,
influencing it to fail.
A good crane setup is on solid, well-drained soils, and the supporting surface
is adequate for the site. Cribbing or crane pads are always used on
outriggers regardless of the surface. In most cases, the general contractor
oversees the construction of specific areas for cranes to sit and work. Any
crane pad constructed must be—and remain—perfectly level.
Telehandlers—A Unique Concern for Working on the Edge
Many rough terrain fork trucks are designed with the boom directly
to the right of the driver's head, obstructing any vision in that area. That design
error was recognized, and changes are being made in some newer models. See the photo of the
telehandler I took in New York. The existing machine photo shows that the operator
cannot see to the right. Some safety managers are comfortable using them on their
worksites; not me.
In addition to the threat of running over fire hydrants, surveyor stakes, and workers, the operators cannot see the edge of the roadway as they travel.
Figure 11: Telehandler That Blocks Operator's View
I was once on a call with the US Department of Energy where they
discussed an accident when a telehandler went off the edge of the road, killing the
operator. I asked if the operator was heading down
the roadway when it happened. There was a long pause and the answer was yes.
This was not an accident; it was foreseeable. Check out the report.
Conclusion
When we go to a rooftop, something primal keeps us away from the
edge. On a construction site, we often need to work at those edges. From fall
prevention to trenches, we must recognize that working on any edge is
ultra-high-hazard work. Those who have fallen or rolled in equipment when it
careened off the edge would agree … if they had survived.
Opinions expressed in Expert Commentary articles are those of the author and are not necessarily held by the author's employer or IRMI. Expert Commentary articles and other IRMI Online content do not purport to provide legal, accounting, or other professional advice or opinion. If such advice is needed, consult with your attorney, accountant, or other qualified adviser.
On a recent construction site visit, I noticed a haul road for trucks right up against the edge of an open excavation site. I pointed out the threat to those tagging along, and they asked, "How far away from the edge should trucks stay?" I replied that, with an adequate berm installed, it would be safe for the truckers and those in the excavation. Both construction workers replied, "What's a berm?"
This article looks at the dangers of "working on the edge." We will review threats we often overlook, the consequences of a safety professional not knowing what a simple berm is (do you?), and sharing a few best practices and lessons that I have learned from real experts.
Roadway Edges
As I walked on a project in Upstate New York with our superintendent, he recounted a near hit that occurred over the weekend. No, it's not a near miss; everyone gets that wrong. (George Carlin provides the best definition.) The photos below show where a berm was needed and the correct berm we later built.
You can see the tracks left by a concrete truck as it rounded the curve, dipping into and out of the trench. The site's response to what could have been a fatality was inadequate at best because they provided a reminder of a threat rather than its elimination. It is not an uncommon approach in construction, but it is not the desired approach. When you eliminate the threat, you eliminate the possible injury.
Work was stopped, a motor grader called up, and berms were built to bounce vehicles back onto the roadway rather than tumble down the bank. How tall should a berm be? The rule of thumb is the height of the tallest machine axle on the project, which is simple guidance. The photo is a great example of how we corrected this killing condition.
The following are some tips for the roadway edge during site work.
Protective Edges
Water-filled plastic barriers have been a godsend to the construction site when providing a protective edge to protect certain areas and the public. When empty, they weigh about 300 pounds, but when filled, they weigh over 1,100 pounds. When I walk a project, I often check to see if they are filled. A solid kick will let you know. And that's the problem—they are rarely filled.
There are few things more dangerous in our environment than someone providing a false sense of security. Since filling them makes them harder to move, many contractors don't fill the water barriers, so the wind, snowplows, and drunk drivers move them with ease.
The following are some tips on water-filled barriers for edges.
When using concrete Jersey barriers, the same holds true. They must be on solid ground and secured to the ground with steel rods. I took the photo of unsecured barriers in New York City. The photo shows barriers that were unsecured, placed too close to the edge, and on melting frozen soil. Gravity was standing by, waiting to cause an accident. Two full-time safety folks did not notice the threat. After I pointed out the danger, work was stopped, and this temporary roadway was closed. The barriers were then removed.
Cranes and Edges
One of the most common contributors to any accident is gravity. While walking a project, I witnessed a huge tracked Manitowoc crane working in the distance. I could see it was not quite level and was working at the edge of an excavation site. The site safety manager and I went over and asked the operator to check the level of the crane. He yelled down that it was out of level by about 3 degrees. I asked him to step down to review the lift underway (concrete distribution box), and that did not go well: He was angry. Questioning a crane operator can be unsettling to the guy doing the asking.
We discussed the frozen ground that was thawing and my concern that the crane looked a bit off. I took out my handy pocket level and placed it on the frame, confirming the crane was out of level by 3 degrees. I then asked how heavy the load was and if he had derated the crane since it was not perfectly level. I explained that a crane off by 3 degrees can only lift about 50 percent of what was intended. He asked, "What's derating?" As we worked on replacing the crane operator, the safety manager asked, "How much weight does it take to tip over a crane like this?" I answered, "One pound. One pound too much."
The photo below confirms crane operators and contractors often overlook two things when working along the edge of something that may fail—gravity and future conditions. In the case shown in the photo, we stopped using this crane until a remedy could be designed. This crane was atop a large rise built specifically (and shoddily by the general contractor) for a crane pad for lifting steel.
Erosion of Supporting Surface Beneath the Support
Cranes are often just on the site for a day. Planning for those types of "picks" is rare. Field conditions may not be suitable, but the crane is there, so the site team often gets to the point of "it's good enough." These photos are a few examples of near hits from cranes that were only working for a day. What is always surprising is the site managers were comfortable with these conditions; I was not.
Crane Placement When Working on the Edge
Besides a solid surface for the crane to stand on, there is also a need to distance the weight and its load of the crane from the edge of an excavation site. In the clay soil photo, you can see that if the excavator swings to the left too far then an accident will occur. But really, that's no accident; he is too close to the edge.
Let's say the excavation is 10 feet deep (where I took the photograph). That would require the outriggers to be 15 feet away from the edge. Otherwise, the weight of the crane and any load would surcharge the edge of the excavation, influencing it to fail.
A good crane setup is on solid, well-drained soils, and the supporting surface is adequate for the site. Cribbing or crane pads are always used on outriggers regardless of the surface. In most cases, the general contractor oversees the construction of specific areas for cranes to sit and work. Any crane pad constructed must be—and remain—perfectly level.
Telehandlers—A Unique Concern for Working on the Edge
Many rough terrain fork trucks are designed with the boom directly to the right of the driver's head, obstructing any vision in that area. That design error was recognized, and changes are being made in some newer models. See the photo of the telehandler I took in New York. The existing machine photo shows that the operator cannot see to the right. Some safety managers are comfortable using them on their worksites; not me.
In addition to the threat of running over fire hydrants, surveyor stakes, and workers, the operators cannot see the edge of the roadway as they travel.
I was once on a call with the US Department of Energy where they discussed an accident when a telehandler went off the edge of the road, killing the operator. I asked if the operator was heading down the roadway when it happened. There was a long pause and the answer was yes. This was not an accident; it was foreseeable. Check out the report.
Conclusion
When we go to a rooftop, something primal keeps us away from the edge. On a construction site, we often need to work at those edges. From fall prevention to trenches, we must recognize that working on any edge is ultra-high-hazard work. Those who have fallen or rolled in equipment when it careened off the edge would agree … if they had survived.
Opinions expressed in Expert Commentary articles are those of the author and are not necessarily held by the author's employer or IRMI. Expert Commentary articles and other IRMI Online content do not purport to provide legal, accounting, or other professional advice or opinion. If such advice is needed, consult with your attorney, accountant, or other qualified adviser.