The Anatomy Of A Billboard Structure

We've all had biology in high school, and can probably name some of the parts of a frog. But can you name the parts of a billboard, and what they do? Let's take a quiz and see.


This is the huge metal tube that holds the sign up in the air. It is one of the heaviest components of the structure, and takes the brunt of the wind load in weather events. The steel monopole got its start from the Alaskan Oil Pipeline - there was so much steel tubing produced that some of it ended up in the billboard industry as a new component to replace I-Beams and wooden poles.


This is the steel square that is welded to the top of the column, on which the head of the sign is attached. The plate contains a large number of holes in it - normally about 12 of them - in which the head of the sign is bolted to the column with enormous bolts that are about 10" long.

Torsion Bar

This is the big horizontal tube that mounts perpendicular to the column, creating a “T" appearance. It has a matching plate with a mirror-image bolt pattern to safely bolt to the column. The piece that holds the plate to the torsion bar is called the “saddle". The torsion bar is normally the second heaviest part of a billboard.


These are the steel I-beams that run perpendicular to the torsion bar, and create the angle of the two sides of the sign, also known as the “V". In a back to back sign, the outriggers are all identical in length. In a “V" sign, the outriggers are in descending length, with the longest outrigger being at the part of the torsion bar farthest from the highway.


These are the steel I-beams that attach to the outriggers, and are vertical in orientation. These are what hold up the advertisements on the sign. They are all of identical length.


These are pieces of steel angle iron that attach to the uprights. They are parallel to the torsion bar, and there are normally about four of them on each side of the sign.


These can be made of either steel or wood, and are, as a group, of the exact dimensions of the sign. They hang on the stringers of the sign. The panels are what the vinyl advertisement is wrapped around and stretched tight over. The panels are normally 4' wide and their length is the entire length of the billboard face (on a 14' x 48' billboard, the panels are 14' x 4', and there are 12 of them side-by-side).


This is the corrugated metal material that hides the torsion bar from view when the billboard is seen from the highway, and is the location of the sign owner's nameplate, also known as “shield". For CBS Outdoor, for example, the metal plate that says “CBS" is the “shield".

Direct Embedment or Bolt Cage Foundation

This is how the billboard column attaches to the earth, and stands up. In a direct embedment foundation, a hole is drilled in the earth, the column inserted, and then concrete is poured in to the top of the hole. In a bolt cage foundation, a huge concrete foundation is poured filled with rebar and a pattern of enormous bolts. The column of the billboard has a second plate on the bottom of the column, and the holes in this plate align with the pattern of bolts in the foundation, and the column is bolted to the ground.


Now you know the pieces of a billboard, and it smelled a lot better than the frog exercise. This general concept of sign construction holds true for all types of structures - from wooden to monopole - with the only exception being the absence of a torsion bar and uprights in a multi-pole billboard, as the poles themselves act as both, and the stringers bolt directly to the poles.

Now you're a billboard structure terms expert.

Frank Rolfe Self Storage Investment Expert
Frank Rolfe started his billboard company off of his coffee table, immediately after graduating from college. Although he had no formal training on the industry, he learned as he went, and developed his own unique systems to accomplish things, such as renting advertising space. Frank was formerly the largest private owner of billboards in Dallas/Ft. Worth, as well as a major player in the Los Angeles market.