How RSS uncovered the true failure point and restored the path to occupancy for a Downtown Los Angeles residential high-rise.
Project Type
Residential High-Rise
Downtown Los Angeles, California
System Type
ERRCS / Public Safety Radio Communications System
RF Modeling Review, Coverage Deficiency Analysis, and Engineering Remediation
The Challenge: Repeated AHJ Failures in Critical Life-Safety Areas
A residential high-rise in Downtown Los Angeles had failed AHJ ERRCS acceptance testing multiple times before RSS became involved. The repeated failures were not random. They were concentrated in some of the most important spaces within the building, including elevator interiors, elevator lobbies, and vertical circulation areas identified by the AHJ as critical for emergency responder communications.
At that point, the building was not dealing with a simple punch-list issue. It was facing a recurring life-safety communications problem that had already resisted prior testing efforts. The owner needed to understand whether the issue was rooted in installation, design, system capacity, or something more fundamental.
RSS was brought in to determine why the system was not performing in the required areas and to establish a technically sound path to compliance.
The RSS Approach: Validate the Real Building, Not Just the Original Model
RSS approached the project as a forensic engineering review. The goal was not to make assumptions about weak coverage or recommend broad replacement before understanding the true condition of the system.
The team reviewed the RF modeling assumptions, as-built field conditions, coaxial distribution paths, and installation quality to determine whether the installed ERRCS system had ever been capable of meeting the building’s actual coverage requirements.
What RSS found was not a workmanship failure. It was a design and modeling failure.
What RSS Found
The RF Model Did Not Reflect the Actual Building Construction
RSS identified that the original RF model did not accurately account for the building’s concrete and steel core walls. These areas had effectively been treated as free space in the propagation analysis, which significantly overstated the predicted coverage performance.
That meant the design was based on signal expectations that were never realistic in the actual building environment. In dense high-rise construction, concrete and steel cores have a major impact on signal propagation, especially in elevator banks, lobbies, and vertical circulation zones.
Because those real-world losses were not properly modeled, the original coverage plots gave a false impression that the system would perform in areas where signal was, in reality, heavily obstructed.
The As-Built Conditions Did Not Match the Design Documentation
RSS also found that the documentation did not match what had actually been installed in the field.
Antenna locations differed from the design drawings, and cable routing shown in the model did not exist as represented. That disconnect created a second layer of performance risk. Even if the model had been accurate, the physical system no longer mirrored the design assumptions closely enough to support reliable prediction.
This meant the project team was effectively relying on documentation that no longer represented the true RF environment or the true system layout.
The Coaxial Distribution Reduced Available Performance
RSS further identified inefficiencies in the coaxial distribution layout. Redundant routing had increased the overall cable length, which reduced link-budget efficiency and limited the number of antennas that each remote could effectively support.
In practical terms, the system had less usable performance margin than expected. That made it even more difficult to serve challenging critical spaces such as elevator cores and vertical circulation areas.
The longer routing did not necessarily mean the system was installed incorrectly, but it did mean that the final network had less RF capability available than the original design likely assumed.
No Installation or Workmanship Deficiencies Were Found
Importantly, RSS did not find evidence of field workmanship failure.
Connectorization and torque were compliant. Manufacturer jumpers were properly installed. Active equipment showed normal operation. No installation deficiencies were observed that would explain the repeated AHJ failures.
This was a critical conclusion because it shifted the conversation away from blaming installation quality and toward the actual engineering issue: the design basis itself did not reflect the building that was built.
Root Cause: The System Was Designed Around an Inaccurate RF Model
RSS concluded that the root cause of failure was not poor workmanship or equipment malfunction. The root cause was that the RF model did not reflect the actual construction and field conditions of the building.
As a result, signal levels in the elevator cores and related critical areas were largely dependent on bleed-through rather than intentional engineered coverage. That meant compliant performance in those spaces was physically unattainable with the installed antenna layout.
The issue was not simply weak coverage. The issue was that the building had been designed around an overstated propagation assumption, leaving critical life-safety areas without a realistic engineered signal path.
The RSS Engineering Solution
RSS developed a remediation plan based on the verified link budget and the actual physical conditions of the system.
Rather than proposing broad demolition or unnecessary replacement, RSS focused on targeted engineering corrections that preserved as much viable infrastructure as possible while addressing the true coverage gaps.
The solution included:
- A central omni antenna in the elevator lobby to improve vertical shaft propagation
- Directional antennas aligned with existing cable pathways to maximize efficient coverage improvement
- Additional antennas only where active equipment capacity allowed
This approach was disciplined and practical. It respected the real limitations of the installed system while creating a coverage strategy based on what the network could actually support.
The Outcome: From Repeated Failure to a Defensible Path to Compliance
RSS converted a recurring and frustrating acceptance failure into a solvable engineering condition.
By identifying the mismatch between the RF model and the actual building, RSS preserved viable infrastructure, avoided unnecessary replacement, and established a technically defensible remediation plan. Most importantly, the building moved from repeated failure toward a clear path for compliance.
The revised approach produced an immediate AHJ inspection pass grade, demonstrating that the issue had not been a mystery at all. It had been an engineering problem that simply required accurate diagnosis.
Key Takeaway
An ERRCS System Cannot Outperform a Bad Model
This project is a strong example of a common problem in complex high-rise environments: when RF modeling fails to reflect real construction conditions, the installed system may never have a realistic chance of passing in the most critical spaces.
For owners and developers, that distinction matters. A failed ERRCS system is not always the result of bad installation. Sometimes the infrastructure is largely sound, but the original design assumptions were flawed from the start.
RSS helps owners and project teams uncover the true reason a system is failing, preserve viable investment where possible, and create a path to compliance grounded in real engineering rather than guesswork.
