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What is Pole Loading Analysis?
Pole loading is the process of analyzing the forces acting upon a utility pole. The process considers the size and strength of a pole, and then considers the forces acting on a pole such as equipment, attachments, and guying. This means that you can evaluate both existing and proposed pole conditions (like a new fiber attachment) against weather patterns that are possible in a pole’s geographic location, usually defined using NESC Loading Zones.
Why is Pole Loading so Important?
Pole loading addresses the two primary concerns of pole owners across the country: safety and reliability. In the event of a “100 year” storm, an electrical grid of properly loaded poles will withstand the abnormal conditions with less damage than if poles are overloaded. When power distribution isn’t built to withstand extreme weather, you could lose a majority of poles in a footprint when a freak storm occurs. This widespread damage leads to massive outages that can result in loss of life.
Additionally, the push for fast, reliable broadband means more communication providers are attaching cables to poles than ever before. These providers tend to think of their cables as light and not a big deal when attached to a pole. When every communications company treats their attachment as having negligible impact on a pole’s load, they continue to attach their unbalanced load to the pole. Eventually, the pole becomes truly overloaded and will break—even in normal weather conditions. This “What’s the problem with one more comm attachment?” mindset causes real safety and reliability issues for the distribution grid.
How Does Pole Loading Software Work?
Pole loading considers the strength of physical objects compared to the loads expected to be placed on them. Nothing is quite perfect (poles are made from one of a kind, not completely round trees after all), so loading analysis helps engineers make good decisions by adding a healthy amount of margin to loading calculations.
Strength factors are added to adjust for physical items that aren’t always operating at their exact maximum strength, so that the system remains robust as poles naturally decay. Load factors are also added so that the grid can handle various unaccounted for anomalies, such as a pole strike down the line, or a branch falling from a tree. These two factors can be referred to as “safety factors.”
How Are Poles Modeled In Loading Software?
When designing new distribution builds, engineers can use standard specifications and build configurations to model their intended design in pole loading software. When analyzing existing conditions for inspection or pole attachment workflows, data collection is required. The following information is usually required to perform pole loading analysis for existing structures:
Pole Locations - or at least all distances and bearings. In order to calculate a pole’s load, the software will require the neighboring poles, downguys, anchors, and more to be located correctly. Traditionally, this type of data collection was performed using a wheel and a clipboard, but modern technology allows most of this information to be automatically calculated in a GIS system.
Pole Specifications - it’s possible that the engineering contractor or requesting attacher has access to a pole owner’s asset records, and it’s possible that the pole owner’s asset records are accurate and up-to-date, but practically, this data is almost always best captured at the pole. For poles with a faded or missing birthmark, pole spec can be estimated by using the measured pole-top height and the measured groundline circumference.
Equipment - Assuming that the attacher doesn’t have access to pole owner records, equipment can still be modeled by taking photos of marked equipment specifications or modeling conservative engineering estimates.
Conductors and Communication Attachments - Pole loading requires the sizes and tensions of conductors and communications attachments. Power maps can be used to assist in sizing conductors, and Katapult Pro has photo tools to measure comm bundles from pole and midspan height photos.
Pole, equipment, and attachment specs make up a pole loading “Client File” or “Catalog.” When using pole loading software, these picklists and standards can be used to model existing conditions using the pole owner’s common build scenarios.
Once necessary data has been collected, designers can build the appropriate models in the software. It will then provide loading results which will inform additional engineering requirements. Some newer data collection platforms can generate JSON and PPLX files so that no design step is required inside the loading software. The final deliverable following the pole loading analysis workflow is an updated makeready design package for work locations requiring construction.
Pole Loading Analysis Tools
SPIDAcalc - Purchased by Bentley, SPIDA Software is one of the most powerful tools used for pole loading. It has a robust JSON import functionality for integrating with data collection tools as well as a flexible user interface.
O-Calc Pro - Created by Osmose, O-Calc is a capable pole loading solution with strength in modeling and visually representing difficult distribution scenarios (such as H-frames).
PoleForeman - Purchased by IkeGPS, Malcolm Young’s flagship offering from PowerLine Technology is a favorite of many Distribution Standards teams at power companies across the US.
PLS-CADD - Also purchased by Bentley, this flagship offering from Power Line Systems is the gold standard for pole loading analysis in power transmission, considering true sag profiles, ambient temperature, and more. PLS-CADD is capable of traditional ruling span analysis as well as three levels of finite element analysis.
Katapult Pro - Katapult Engineering’s data collection software now includes Integrated Pole Loading which leverages an internal analysis engine to provide results to designers in real-time as they call make ready.
For more information about pole loading analysis, or to learn more about how Katapult Pro integrates with other tools, contact us at here, call us at 717-502-4510, or email us at sales@katapultengineering.com. Thanks for reading, and we hope to assist you in your next pole loading project!