# Why build a cell lattice tower with square cross-section instead of triangular cross-section?

First, a neat image from Wikipedia

Here the cell tower has three vertical (or maybe slightly inclined to the inside) thicker pipes which are located at angles of a triangle and those three thicker pipes are interconnected with numerous thinner pipes and this yields a lattice tower with triangular horizontal cross-section.

Clearly you need at least three vertical pipes to make this happen. The design above with triangular cross-section is very popular.

However sometimes cell towers are built with square cross-section - they use four vertical pipes located at angles of a square instead of three pipes. It looks like waste of steel and design complication - what can a tower with square cross-section do what one with triangular cross-section cannot?

I could imagine there're was a difference when a tower had notable load concentrated in one direction. Yet I'm asking about cell towers that carry rather lightweight equipment and mostly have to withstand wind loads.

Why are square cross-section cell towers used instead of triangular cross-section towers?

• Don't underestimate wind load, especially when the tower is covered with ice and the wind crossection is signifcantly more than just the bare metal pieces. Mar 2, 2015 at 14:47
• @OlinLathrop I know that wind load can be a serious issue but it's equally probable from any side so my guess is a tower with triangular cross-section can deal with it just as well as one with square cross-section. Mar 2, 2015 at 14:55
• Actually that is one issue of triagular crossection. The difference in strength by direction varies more with a triangle. The triangle has to be built with the weakest direction being able to handle the maximum design load, so is more over-built in the stronger direction than crossections with more sides. Mar 2, 2015 at 14:59