Building Better Telecom Infrastructure From the Ground-Up with Helical Piers

Helical foundations are making communication infrastructure construction faster, stronger, and longer-lasting. Here's everything you need to know about this technology that's rapidly transforming the industry.

Introduction

The demand for telecommunication infrastructure is absolutely screaming in the U.S. right now. Billions of dollars are being poured into tower construction, especially for 5G rollouts. When it comes to supporting all these new towers, concrete is pretty much the default foundation solution. 
But is it really the best option?
Helical pier foundations are being extensively used as an alternative to concrete for supporting telecom towers in countries like Canada and the United Kingdom. Here in America though, we've been slower to catch-on. Although helical foundations have been used as ground anchors to secure guy lines since the 1950's, we aren't seeing their widespread adoption as a foundation for the towers themselves.
We think this is a seriously missed opportunity, given the fact that helical piers can: 
● Significantly expedite construction timelines● Practically eliminate site prep● Slash environmental impacts● Make rural or remote construction far more economical
In this article we're giving you the complete story on helical pier foundations for communication tower construction. We'll cover where the technology comes from, how it works, what it can support, and why you should consider using this solution for your next project.

Helical Pier Foundations & How They Work

So, what is a helical pier foundation? 
There's some confusion about this in the construction and engineering world, mostly thanks to the fact this technology has a few names. When they were first invented in the 1830's by a fellow named Alexander Mitchell, he termed them "screw piles" which is a name that's still in use today.
However, as the decades went on, the term "helical pile" came to be favored as it better defined what makes this foundation unique - namely its helical-shaped blade (also known as a "helix plate")
As the technology has grown to be used across the world, regional terms have appeared like "screw pier" or "helical pier". At S&B Helical we call them helical piers; but just know that screw pile, screw pier, helical pile, or helical pier, all refer to the same thing.
Note that you might also see some people refer to "ground anchors" or "ground screws". These are not the same technology, and don't possess the features that make up a true helical pier. 
Speaking of what makes a true helical pier, let's talk about what this technology actually is and how it's defined.

Definition of a Helical Pier

The best definition of a helical pile comes from a book written by Howard Perko, Ph.D., P.E., titled "Helical Piles: A Practical Guide to Design and Installation". Quoting from page 5 of that book:

That's about as clear and short a definition as you can get, but it also illustrates a key difference between helical piers and other foundation solutions. 

Pay attention to this particular aspect - "rotated into the ground". That's a big difference compared to bored or driven piles, as the installation of a helical foundation not only causes minimal disruption but also results in (essentially) no spoils.
A true helical pier has one or more helix-shaped bearing plates with a specific design and pitch. Structural loads and transferred down through the pier shaft and into these plates, which are anchored in firm soil layers. (Note - in the case of piers which are installed to bedrock, it's the shaft itself which carries the load.)

How Does a Helical Pier Work?

With that definition in mind, you're probably already getting a pretty good idea about how a helical pier works. As mentioned, they're installed by rotating them into the ground. To achieve this, we use hydraulically-powered gear motors attached to machines like excavators or skidsteers. 
These gear motors, called helical anchor drives, come in a wide range of capacities measured in ft. lbs. of torque. Typically speaking, bigger piers require more torque to properly install them or to advance through dense soils.
Speaking of torque, that's one of the aspects of helical piers that really sets them apart from other foundation solutions.
During the installation of a helical pier, the soil exerts increasing pressure as it advances downward. This pressure is especially pronounced on the helix plates. Dense soils, such as heavy clay, will exert more pressure on the pier - meaning more torque is required to install it. The physical dimensions of the pier also play a key role in determining installation torque.
Now, here's what's fascinating (and powerful) about the interaction between a helical foundation and installation torque. It's been proven there's an empirical relationship that exists between the install torque exerted on a helical pier, and its ultimate axial load capacity in compression and tension. This is expressed in the equation:
Qu = Kt * T
● Qu represents the ultimate pier capacity (in lbs)● Kt is the torque correlation factor● T is the final installation torque.
The figure used for Kt depends on shaft and helix plate size. For example, the ICC-ES AC358 lists a 'default' Kt value of 7 ft-1 for a 3.5-inch (OD) round pier shaft. Taking this default Kt figure, we can put together a sample equation to show you how this calculation looks in practice.

Torque-to-Capacity: Proving Foundation Performance in Real-Time

Let's use the Kt value of 7 ft-1, and assume a final installation torque of 9,500 ft. lbs., The calculation would look like this:
Qu = 7 x 9500
Qu = 85,000 lbs (85.5 kips)
So, in our theoretical example, if we installed a 3.5-inch (OD) helical pier to a torque of 9,500 ft. lbs., it would have an ultimate capacity of 85.5 kips. However, that figure does not include a safety factor, so we need to perform one more calculation:
85.5 kips / 2.0 safety factor = 42.75 kips ultimate capacity
It's this unique interaction between a helical pier, installation torque, and ultimate capacity, that sets this technology apart from other options. This equation allows us to perform real-time quality control during foundation installation, and help identify problematic piers in the field. Plus, for low-risk structures, an engineer may accept this calculation as proof of pier performance.
However! Torque-to-capacity correlations are not the "be all end all" solution for determining helical pier capacity. When it comes to confirming pier performance beyond a doubt, you can't beat a full-blown load test. Still, torque correlations are a powerful tool that makes a helical foundation install more efficient, safe, and effective.

Why Aren't Helical Pier Foundations Being Used for Telecom Towers in America?

Now that you know what helical piers are, you might be wondering why they aren't more commonly used for telecom tower construction here in America.
The first thing to clear-up is the fact that even though helical foundations haven't seen widespread adoption for telecom construction here in the U.S., they most certainly are seeing heavy use in places like Canada and the U.K. 
This is probably down to the fact that (and this pains us to say), other nations are simply further ahead on adopting helical foundations than we are. 
In fact we've heard some industry folks estimate that America is about 20 years behind the curve on this technology. That's one of the reasons we wanted to write a deep-dive into the application of helical piers in this field - more awareness is sorely needed in our country. 
After all we can't let the Canadians of all people beat us at building infrastructure, right? (Just kidding, Canada, we actually think you're great people!)
A big reason for the slow adoption of helical foundations in certain industries, we believe, comes down to some myths and misconceptions that continue to hang around. Our team wrote a full article on this which you can read here, but to give you 3 of the most common ones...

There's no reason helical piers can't be used for telecom construction, and as you'll see later in this article they could be the best option depending on your project. But before we get to that, it's worth taking a moment to assess some of their real-world applications for communication towers. 

What Types of Telecom Towers Can Helical Piers Support?

You know, there's another myth about helical piers we've heard before that has to do specifically with telecom construction...
It's the idea that helical piers are only good for certain types of towers. For instance they might be great for small towers with light loads, but you can't really use them for something like a massive guyed lattice tower - right?
In fact, helical piers are more than capable of meeting the demands of all types of telecom towers. If we break down these towers into three main categories, here's what it looks like in practice:

Guyed Towers

Hundreds of feet tall and carrying huge amounts of communication equipment, guyed towers are one of the most impressive and challenging telecom structures out there. With their enormous height and heavy loads they demand a solid foundation not only under the tower itself, but also for the numerous guy lines supporting it.
This is where helical piers shine, as they can deliver large load capacities in both compression and tension. That means you can use them under the tower and also to secure the guy lines, ensuring they never pull out of the ground.
A big benefit of using a helical foundation is the greatly reduced installation time and land disturbance. Typically, a tall guyed tower would demand a bulky concrete foundation - particularly for the guy wires which require large deadman anchors.
Helical piers have a far smaller footprint, while still delivering the strength of concrete. Since they're rotated into the ground with no excavation, they save a significant amount of time and are better for the surrounding environment. Plus, you won't have to figure out what to do with all the spoils after digging for concrete.

Monopole Towers

Monopole towers have some interesting foundation demands thanks to the fact they're tall, narrow, and don't use guy wires for lateral support. The result is they often get built on very large, and deep, concrete piers. And while there's nothing inherently wrong with that, it does demand a lot of excavation, soil disturbance, and raw materials. Not to mention the time spent installing the foundation and waiting for curing.
Helical piers, as we've established, don't require excavation and eliminate the need for curing. But, a lot of engineers and contractors doubt their ability to withstand the challenging loads exerted by a monopole tower.
The trick is, we wouldn't just install a single helical pier to support this kind of tower (or any other, to be honest!) 
One of the things about a helical foundation that makes it so versatile is our ability to tie multiple piers together using a special cap, grillage, or frame. By grouping piers together, we can dramatically increase their axial and lateral load capacity. So, even if they're supporting a monopole tower with complex loads, the question of securing enough capacity isn't really a question at all.
If the lateral loads are expected to be very significant, for example in areas prone to high winds, we can use a battered pier installation to overcome even the most demanding conditions.

Self-Supporting Lattice Towers

With a smaller overall footprint than guyed towers, and using less material than monopoles, self-supporting lattice towers continue to be a popular choice for telecom infrastructure. And as you may have already guessed, a helical foundation can support them.
A common foundation solution for 3 or 4 leg lattice towers are concrete piers set under each leg. This has been a pretty good solution for many years, but there are a few pitfalls. The slower, more disruptive, and labor-intensive, installation process is certainly one of those (as we've covered). But, it's their propensity to experience heaving in expansive soils and cold climates that should also be a concern.
The problem of supporting a relatively light structure like a lattice tower is that, to an extent, a concrete pier relies on having a fairly significant axial load to prevent heaving. Since a lattice tower is (compared to it's physical size) a pretty lightweight structure, it may not exert enough axial load on the large-diameter concrete piers needed to support it.
This is, again, where helical piers bring a unique edge. Because of their combo of large-diameter helix plate(s) and comparatively smaller pier shaft, they provide excellent resistance to uplift forces even in highly expansive soils.
Depending on the size of the tower and load requirements, you may only need a single pier for each leg. In more demanding scenarios, we can again tie multiple piers together to support each leg and maximize foundation strength in a compact footprint.

Why Use Helical Foundations for Telecom Tower Construction?

We've already covered a lot of the benefits of helical piers for telecom tower foundations throughout this article, but it's worth summarizing the reasons why you should consider this solution for your projects.

Frequently Asked Questions About Helical Foundations and Telecom Construction

Conclusion

The reality is that a greater number of towers are needed in more locations with tougher conditions than ever before. This demand for telecom infrastructure is only going to grow in coming years; as the needs of this market evolves, so too should the technology used in its construction. 
We'll never make the claim that helical piers are a "miracle foundation", and we're not interested in bashing concrete. But it's also more than fair to say they represent a faster, easier, and cleaner way to build. Their adaptability, quick installation, large load capacities, and ability to easily install in remote locations, makes them a solution worth exploring for your telecom projects.
Yes, there will still be times where concrete is a better option depending on your specific demands and site conditions. But, you'd be surprised how often a helical foundation will be capable of delivering better results in a fraction of the time and effort.
So, there's no better time than now to explore this technology further and see how it can streamline your telecom construction process!
Our team at S&B Helical has been designing and installing high-capacity helical pier foundations across America since 2015. We know how to handle large-scale commercial and industrial projects, and are ready to help you find the right support for whatever tower you're looking to build.
Get in touch with us today, we'd be happy to demystify helical foundations and help you uncover if they could be the perfect fit for your next project.