From time to time, I see pictures and hear stories of concrete pump trucks working in difficult situations.
They have little to no supporting materials, outrigger pads, or dunnage, and unnecessary risks are being taken.
Unfortunately, the industry still has a cultural undercurrent that the bigger the risk, the better the reward. All too often, people say, “Send it! It will be okay!”
Thankfully, more often than not, less-than-ideal setups hold, and everyone moves on to the next job with a sigh of relief. That said, as anyone who’s worked around concrete pump trucks for any period of time knows, sometimes people don’t get so lucky.
Near misses and accidents happen. People get hurt.
Many of these incidents, though, are preventable.
While I understand how difficult it can be for operators to get their jobs done while setting up with optimal safety, risks can be mitigated with basic planning and preparation. Toward that end, I want to offer you three simple planning steps our team at DICA emphasizes to owners and operators to make sure they get their dunnage systems right — regardless of what dunnage they plan to use.
Step #1 – Know your numbers.
The two critical numbers required to determine the total area needed to support your equipment are the Maximum Outrigger Reaction Force (MORF) and the Allowable Ground Bearing Pressure (AGBP).
Maximum Outrigger Reaction Force – This value can be found on each outrigger leg. This number represents the maximum load the outrigger can generate as determined by the manufacturer.
Allowable Ground Bearing Pressure – This number represents the amount of pressure you are allowed to impart on the ground. Ideally, the allowable ground bearing pressure is dictated by the controlling entity. (For more information on soil types and the difference between the ultimate and allowable ground bearing pressures, see Determining Your Ground Bearing Capacity.)
Here’s an example:
Equipment: Schwing 47 meter pump
Maximum Outrigger Reaction Force: 58,460 lbs
Allowable Ground Bearing Pressure: 25 psi or 3,500 psf
58,460 lbs / 3,500 psf = 16.7 square feet of area.
In other words, for this pump, if the AGBP is 25 psi (3,500 psf), you need at least 16.7 square feet of dunnage to reduce the outrigger load to the allowable ground bearing pressure.
Step #2 – Engineer Your Dunnage.
You don’t want to leave your safety to chance.
To reduce risk, you need to take the guesswork out of your dunnage by having an engineered dunnage system specific to each of your pumps. These supporting materials must be engineered based on your numbers from Step #1: your outrigger loads and allowable ground bearing pressures.
Here are three criteria your engineered dunnage needs to get right:
1. It must be of an appropriate size to reduce the pressures imposed on the ground to meet expectations. The minimum size is the area calculated from your numbers.
2. It must have the strength required to support the load and pressure without physically failing.
3. It must have the stiffness required to effectively distribute the load over the intended area and resist excessive deflection.
Different materials such as wood timbers, plywood, steel, and synthetics can all be appropriate solutions. To properly mitigate risks, be sure to inspect your materials before each use. Additionally, be sure to engineer your supporting materials to meet or exceed your requirements. Consult with manufacturers such as DICA to help ensure these requirements are being met.
Step #3 – Use Good Sense.
Smart operators are always on the lookout for Murphy’s Law. They know even the best setups are no substitute for situational awareness.
Knowing your numbers and engineering your dunnage systems are musts for mitigating risk. To ensure safe operation, you also need to be good at this third step: staying aware of what’s going on while you’re working. Whether you’re driving the pump truck to the site, selecting the correct setup location, assembling your supporting materials, placing or moving the boom, or pumping, you must monitor what’s happening each step of the way.
If something can go wrong, it will go wrong, especially with concrete pump trucks. Due to the dynamic loading, the pump or setup can move while pumping. Being situationally aware will help prevent serious accidents or damage to property or people.
To stay safe, here are some things to watch out for — and what to do if you spot them:
- If your supporting materials are showing significant deflection (bending), stop. Your dunnage is not stiff enough.
- If the supporting materials are being driven into the ground, stop. The area of your dunnage is too small, and the area needs to be increased.
- In general, if it doesn’t look right, stop. If it doesn’t act right, stop. If it doesn’t feel right, stop.
You never know — the life you save may be your own.
The most important thing you can do:
When it comes to setting up your pump, ensuring your safety and the safety of those around you should be the most important thing.
I get it. Sometimes, even with the proper preparation, pump truck owners and operators find themselves in compromised positions. Operating safely isn’t always easy. However, like most everything in life, you always have a choice. Our greatest power is our power to choose.
I have one additional safety tip for you: Resolve to speak up when danger seems to be lurking. It’s not easy, but knowing your numbers, having an engineered dunnage solution, and using good sense should give you the confidence to do so.
While schedules can be pressure-packed, and job sites are fast-moving, safety is paramount. By implementing these three simple safety steps and by having the fortitude to drive off a job if you have to, you’ll reduce your risk, increase site safety, and provide everyone more peace of mind.