Field notes · 31 August 2026
What a colocation structural analysis actually checks
Before a carrier hangs equipment on an existing tower, someone has to demonstrate the structure can carry it. TIA-222 requires that analysis before any modification to mounted equipment. Here is what the analysis looks at, and what usually decides whether it comes back buildable.
Why it exists
The standard asks for it before the change, not after.
ANSI/TIA-222 is the US standard for the structural design of antenna-supporting structures. It has been revised repeatedly since 1959, most recently by Revision I, effective 1 January 2024, and it requires that a communication structure be analysed before equipment mounted on it is modified.
In practice that means a colocation — adding a new tenant, or a existing tenant swapping to heavier equipment — triggers an analysis whether or not anything about the tower itself changes. The tower did not get weaker; the demand on it changed.
What goes into it
The answer is only as good as the inputs.
Analysis software is not the hard part. Every credible firm runs an industry-standard package, and given identical inputs they broadly agree. What separates a reliable analysis from an unreliable one is whether the inputs describe the tower that is actually standing.
- Tower geometry and membersHeight, section breaks, leg and bracing sizes, and connection detail — taken from drawings where they exist and verified by mapping where they do not.
- Existing loadingEvery appurtenance already on the structure: antennas, mounts, lines, platforms, waveguide. Missing appurtenances are the most common reason an analysis is wrong in the optimistic direction.
- Proposed loadingThe new tenant's equipment, mounts and lines, at the elevation requested.
- Environmental criteriaWind and ice loading per the governing revision and the site's location, plus the structure class and exposure category.
- Foundation and anchorageWhere the analysis reaches the base, the foundation and anchor bolts have to carry the result too.
The input that decides it
An accurate tower map is worth more than a faster solver.
A tower mapping visit records what is physically on the structure and where. Where drawings are old, incomplete, or describe a tower that has since been modified, mapping is the only way to know the starting condition.
An analysis run against an incomplete appurtenance list will pass structures that should not pass. That is a worse outcome than a slow analysis, and it is the reason mapping is treated as part of the engineering rather than an optional survey.
Three answers, not two
Pass, fail, or buildable with modification.
A colocation analysis rarely ends in a simple yes or no. The common third outcome is that the structure carries the proposed loading once specific members or connections are reinforced — which turns an engineering question into a cost question the carrier and the tower owner can actually decide on.
Aria performs the analysis and seals the report. We do not fabricate or install modifications, and we do not decide whether a reinforcement is worth doing — we produce the number that decision is made from.
In short
TIA-222 colocation analysis
- ANSI/TIA-222 requires a communication structure to be analysed before equipment mounted on it is modified, so a colocation triggers analysis even when the tower itself is unchanged.
- The current revision, TIA-222 Revision I, took effect on 1 January 2024.
- A colocation analysis takes in tower geometry and members, all existing appurtenances, the proposed loading, wind and ice criteria for the site, and the foundation and anchorage.
- Analysis run against an incomplete list of existing appurtenances will pass structures that should not pass, which is why tower mapping is treated as part of the engineering.
- The common third outcome is not pass or fail but buildable with specific reinforcement, which converts an engineering question into a cost decision.
- Aria performs and seals tower structural analysis. Aria does not fabricate or install tower modifications.
- Aria's professional engineers hold licensure across 48 states, plus the District of Columbia and Puerto Rico, and maintain NCEES records for comity licensure elsewhere.