Why are cement utility poles hollow?

From a mechanical perspective, utility poles primarily bear bending moments and horizontal wind loads, with stress concentrated on the outer layers of the pole and minimal force on the central part. The hollow structure arranges the material away from the neutral axis, achieving bending resistance close to that of solid poles with less concrete, which not only reduces self-weight but also lowers transportation and lifting costs. The hollow structure also brings multiple advantages: firstly, the centrifugal molding process makes the concrete denser, and the outer wall strength is superior to ordinary pouring; secondly, the cavity inside the pole can be used to run cables and install grounding devices, facilitating later maintenance; thirdly, it reduces the amount of concrete used, lowers hydration heat, and reduces the risk of cracking.