Applications

Light Pole Foundations

A fast and simple foundation solution for tapered steel light poles, monopoles and lattice tower structures. Screwpiles, as opposed to conventional mass concrete bored piles, deliver significant advantages of cost and time savings.

Our "Lightpole Screw-in Steel Foundation System" is the quickest method of installing engineered foundations and erecting lightpoles, as there is no concrete curing waiting time. The entire process is reduced to just screwing a foundation into the ground, excavating a small power cable access trench, feeding the power cable through the cable slot provided, lifting the pole and bolt connecting the base plate to the connecting plate that is provided on the screwpile. No ragbolt cages or messy concrete is needed. The issue of high watertables becomes irrelevant and there is no need to recompact the backfilled cable trench. Electrical contractors have the potential to save time and money by using screwpiles over conventional foundation methods.

The information necessary to determine the type of screwpile foundation required is:

  1. Pole height and weight
  2. Allowable bending moment load (ultimate or SWL)
  3. Allowable horizontal (lateral) shear load (ultimate or SWL)
  4. Pole baseplate and connecting bolt configuration
  5. Site-specific ground conditions and exposure classification
  6. Installation location and quantity required

A single screwpile foundation solution is available for monopoles up to 25 metres. Multiple configurations are available for lattice towers up to 50 metres. In locations of high wind loads, such as cyclonic regions, grouped screwpile options utilising a concrete pilecap may be appropriate so that soil passive resistance can be utilised. Bending moment loads of up to 150kNm can be accommodated using a single screwpile.

Lightpole foundation products need to be hot dipped galvanised for protection against exposure and are typically designed for a minimum 35 year design life. The design life can be extended upon request.

Important Notes:

  • Unlike other products, Screwpile Australia’s lightpole screw-in steel foundation system does not use shallow vertical fin plates to transfer the horizontal loads into the ground, or to stiffen the pile shaft.
  • Screwpile Australia’s engineers believe the practice of relying on shallow vertical fins to structurally support the foundation loads is flawed for the following reasons:

*       It cannot be guaranteed that surface compaction is present or adequate.

*       Trench excavation next to the pile shaft and fin assemblies is necessary to install the power cable. It cannot be guaranteed that the backfill will be compacted in accordance with the intended design specification.

*       This is critical as finned foundations are inherently shallow and any loose upper soil zone may result in excessive pole movement under high wind loads and possible pole or foundation failure.

*       It is common for no site-specific soil density information to be made available at lightpole locations and a generic attitude towards pile design is considered dangerous.

*       Our engineers would not provide engineering certification for the installation of screw-in steel foundations in these circumstances, as certification should be in two parts. 1) The structural certification of product and 2) The final installation outcome.