How do the different foundations and methods of site lighting bases compare, which ones are trending, and why?
Properly installed light poles not only enhance visibility and safety, but also contribute to the appearance and functionality of outdoor spaces. Once the pole style is decided, choosing the right foundation design is critical to creating a solid and stable base for light pole installation. Considerations such as soil quality, pole height and environmental conditions all factor into this decision. Methods include Direct Burial, Helical Pile, and Poured-in-Place Concrete. More recently, Precast Concrete bases have made significant inroads, and due to the many advantages, we predict this trend will continue to grow. Read on for more detail on the considerations and factors surrounding each methodology.
Direct Burial of steel or aluminum poles is relatively low-cost and easy because it doesn’t require building a base for pole installation. The pole and footing are continuous, which forms a stronger structure. The lack of a base also allows landscaping directly up to the pole; installation is faster and doesn’t depend on weather, form work or pouring schedules. But direct burial doesn’t work well in sandy or loose soil, and is difficult in hard/rocky ground. It also lacks a “bumper,” so vehicular impact damages the pole. In addition, owners prefer the visual of a base to assure them that there is a solid foundation below ground.
Helical Piles are less common, but particularly useful when the site involves wetlands, harbors and weak soil areas. To understand this somewhat unfamiliar method, imagine that the base is essentially a long screw, drilled deep into the earth with specialized equipment. A benefit of helical piles is increased predictability of performance due to the empirical relationship between installation torque and soil capacity. They are customizable and reliable, but require a geotech survey and an experienced engineer to handle the design. Light capacity helical piles are installed with portable hydraulic torsion bars or towers, skid steers or excavators and utility sector style auger trucks (Digger Derricks). High capacity helical piles are installed primarily with modified drill rigs and custom equipment. Since specialized hydraulic equipment is needed, specialized suppliers must be enlisted, which can affect the project timeline and overall cost.
The Poured-in-Place concrete base is tried and true and well understood by contractors. However, it requires the coordination of many steps, from drilling the excavation, to placing the cardboard form and rebar, properly templating, fabricating and securing the conduit openings for electrical wiring. And it can be challenging to get the mixer truck close enough to pour the concrete base. This process also necessitates waiting another 7-10 days for the concrete to cure, and patching and cleaning up the base—and hoping there are no delays with rain or scheduling inspections. Poured-in-place bases show wear and tear over time, and must be replaced when they deteriorate and fail.
With pandemic-rooted labor shortages and associated challenges of finding workers with the skill level and expertise to properly execute the time- and labor-intensive process of pouring concrete bases on site, Precast Concrete is a trending solution to many of these problems. According to Zainn Ison, head of Business Development for Redi-Rock Structures, “Precast bases are catching on with the established contractors; they’ve seen it in other projects and are reaching out to give it a try.”
Precast concrete is created off-site and delivered to its project destination for immediate use, which saves time and helps keep work on schedule. Precast is plant fabricated under controlled conditions, so every piece meets the desired specifications. It is extremely durable, can support heavy loads and is versatile across many uses. Contractors may not be used to the upfront costs and the required transportation to the job site, but the quality, consistency and reduced labor expenses more than offset the initial costs. When installing multiple light poles that require repeatable components, precast concrete is much faster to install and requires significantly less labor. The maintenance cost is also reduced, because concrete cast in a factory-controlled environment is stronger and longer-lasting than site-poured alternatives.
Precast concrete bases such as those made by LPB (lightpolebase.com) simplify this process even further by utilizing an Adjustable Anchor Bolt System that allows different bolt patterns to be determined on-site to fit exactly with the pole being attached. This feature, along with four Universal Conduit Pathways, means it can be manufactured in advance, held in inventory, and immediately available when needed—making it one of the fastest, easiest and most efficient light pole bases to install.
Notes Luke Sheetz, director of Electrical Construction at Edwards Electrical & Mechanical shares, “Before precast concrete pole bases were adopted in this area, concrete supply issues resulted in long lead times and the supply priority went to bigger players. Incorporating precast bases took a 1-2 week process down to a single day to install, and has made it possible for teams to keep up with installations driven by the continuing growth of fulfillment centers and their parking lots.” He also notes that the flexibility to vary the bolt pattern and add an extension makes it possible to quickly and easily install the higher light poles needed at these logistics centers while keeping the existing foundation in place.
Erin Kelly is Research and Marketing Director for Rethink Precast Marketing, Coon Rapids, Minn.; www.rethinkprecastmktg.com.
