Poles, Foundations, Supports, and Structural Considerations
Domain 4 - Poles, Foundations, Supports, and Structural Considerations
This domain tests whether you understand the load path from luminaire to soil and the safety features that protect vehicles and workers. It is not a civil-engineering exam, but you must recognize design responsibilities and inspection points.
Core rules
- Poles must resist dead load, wind load, ice, and luminaire projected area; AASHTO LTS is a common reference for structural supports.
- Breakaway or frangible supports are required in clear zones on high-speed roads; transformer bases and slip bases are common. Breakaway hardware must not be replaced with rigid hardware.
- Foundation design depends on soil bearing capacity, embedment depth, anchor-bolt circle, bolt grade, and concrete strength. Anchor bolts are often template-set and grouted after leveling.
- Handholes should face away from traffic and be accessible; pole verticality is checked with a level or plumb; metal poles require grounding and bonding.
- Corrosion protection matters in coastal and deicing-salt environments.
Worked example
A square foundation is 1.2 m × 1.2 m × 1.8 m. Volume = 1.2 × 1.2 × 1.8 = 2.592 m³. At 2,400 kg/m³, concrete mass ≈ 6,221 kg. This mass contributes resistance to overturning, but the design must still check soil bearing and wind moment; mass alone does not prove adequacy.
Traps that cost marks
Replacing breakaway bolts with standard bolts, ignoring luminaire effective projected area, setting poles without checking bolt-circle alignment, leaving handholes facing traffic, and assuming a concrete volume guarantees structural capacity.