When Tower Design Meets the Real World: How Antenna Selection Must Adapt During the Site Development Phase of a New Tower Build

John Keating, P.E., EVP of Market Operations
Centerline Solutions

This article is Part 2 in a series that Antenna Systems & Technology has invited me to write about how antenna selection evolves over the course of a new wireless tower project, impacted by factors that emerge during each of the three phases of these projects:

  • The initial RF design and antenna selection phase
  • The site development phase, which includes site Engineering, leasing and permitting; and
  • The final phase of tower construction and testing

In Part 1 of this series, I walked readers through the factors that influence initial antenna selection when the project is on the drawing board, including parameters such as coverage requirements, radio equipment configuration, antenna performance parameters (i.e. gain, vertical beam width, horizontal beam width) and antenna installation parameters (i.e. height, azimuths, tilts). The result of that initial phase is an idealized design that serves as a starting point for the tower project, but the harsh reality for RF Engineers is that their initial design may undergo significant changes before the construction of the tower is actually completed. In jurisdictions with restrictive telecommunications ordinances, it’s not uncommon that the final build bares very little resemblance to the initial design, but that does not mean the initial phase was in vain. All the work that RF Engineers do during the initial design and antenna selection phase is crucial to the project, providing a foundation for each decision that comes later in the process.

Once the RF Engineer has completed that initial design, the new tower project enters the site development phase, and that is when things start to change dramatically. There are three primary “actors” who enter the stage during this part of the process, and the plot becomes more complex with each of their entrances, sparking revisions to the RF design in the process. The goal of this article is to give the RF Engineers who read Antenna Systems & Technology a chance to get inside the minds of these other participants in the process. Understanding what each of these stakeholders wants and why they are doing what they are doing will enable RF Engineers to “speak their language,” collaborate more effectively, and steer the project toward a final outcome that meets everyone’s needs.

The Site Acquisition Manager Enters the Picture
The first new “actor” to enter the scene is typically the Site Acquisition Manager, whose job is to take the initial tower design created by the RF Engineer and begin mapping that to the realities of available real estate, the complexity of working with landlords, the requirements of municipal bodies and more. Based on the initial design of the RF Engineer, a search area release form (SARF) document is created to map out the geographic boundaries for the location of the new site in order to meet the coverage needs intended for the project.

In addition to geographic boundaries, there are typically also criteria in the SARF such as tower height and number of antennas that need to be followed. The RF Engineer may provide very specific direction on preferred locations within the search area, as well as areas of interest such as shopping centers, sports arenas, schools, etc.—but those recommendations are made from a purely technical point of view. The mission for the Site Acquisition Manager is to use the idealized preferences in the initial design and take a major step forward for the project by finding locations that will work not only from a technical perspective, but also in alignment with a long list of practical factors, such as available real estate and regulatory requirements.

With the SARF in hand, the Site Acquisition Manager proceeds with three key criteria in mind that begin to influence how the tower project will evolve:

Schedule Has an Enormous Impact – One of the factors that most quickly rules out ideal sites for new tower builds is the length of time that would be required to get from the starting line to the finish line. The Site Acquisition Manager knows all too well which sites are likely to get bogged down in prolonged acquisition/approval cycles, and many of the recommendations they make will be based on their understanding of what is realistic in certain time frames. For example, if your customer is looking to have a site on the air in six months, bringing forth candidates that require a 12-month zoning process will probably not be well received.

The Site Acquisition Manager will want to set the project up for success by steering the process toward sites that match the timeframe of the given project. One major factor in this step in the process will be proximity to residences and schools. Even though wireless technology is nearly ubiquitous in U.S. households, there is often well-organized opposition to new tower builds that are near residential areas and schools, which can lead to long delays or even project cancellations. The Site Acquisition Manager will navigate that minefield of potential delays to find sites that are realistic matches for the timeframe of the tower’s construction.

Towers camouflaged as cacti can be costly, but are very hard to spot.

Towers camouflaged as cacti can be costly, but are very hard to spot.

Cost Plays a Big Role – Putting up wireless towers would be a lot simpler if cost were no object. But cost plays a major role during the site selection process, and it can force a tower to move from locations that are ideal from a technical perspective to locations that force the RF Engineer to adjust the project design. There are several things that can drive up the capital cost of building a new site: long access roads and/or utility runs, extensive landscaping, and walled compounds to name a few. In general, the more complicated the build is, the more expensive it is.

Another factor that can dramatically increase cost is the need to add camouflaging to a tower to meet aesthetic requirements of a given neighborhood. In fact, camouflaging can often double the cost of a project, not simply because of the camouflage elements but due to the cost of additional structural strength to accommodate the wind load of the tower’s larger profile. Disguising new sites as pine trees, palm trees, cacti, bell towers, flagpoles, etc., has been somewhat common for the last 20 years. Each of those methods can be extremely effective in minimizing the visual impact of the new site.

The use of mono-pine structures is somewhat common in my home state of Colorado. And, even though I may know exactly where many of the “fake” trees are, they can still be very difficult to spot for the general public. The key to their effectiveness is in placing them in the proper setting, with the correct proportion, taper, scale, color and texture. Proximity to the viewing public is also important. Even a well-executed disguise will be obvious when viewed up close. If not done properly, disguising or camouflaging a site may in fact result in greater attention being drawn to it.

Can you spot the wireless tower in this image?

Can you spot the wireless tower in this image?

Another major cost driver on the expense side is the lease. Over the lifetime of the site, a wireless service provider will spend far more on the cost of the lease and utilities, than they will have spent on the construction of the site. Thus, lease negotiations can be very difficult for the site acquisition specialist, as they must balance the needs of their client (the wireless service provider) with the wants of the prospective landlord. The service provider will want lower monthly lease rates, automatic renewals with low lease escalators, termination rights, rights to modify their site, etc. The landlord, of course will want the counter to many of those things to maximize their revenue and lower risk, and that can impact the cost and timeline for these projects.

Don’t Forget Quality – Perhaps the most important requirement of the new site, but also the most difficult to measure, is its quality. RF Engineers have a couple of pieces of information available when they design the proposed new site: 1) How the network looks today, which is empirical; and 2) how it will look once the site goes on air, which is largely theoretical. As good as computer modeling has become, it simply cannot resolve all the real-world complexities of signal propagation and dynamic traffic (cell use) loading, with the same precision of a financial budget or a project schedule.

Because the relative quality of one new site candidate over another can be so difficult to precisely measure, it is challenging for the RF Engineer to quantify the expected increase in quality of one site over others, in terms of dollars or schedule overruns. For example, is a radiation center that is 20 feet higher than the others worth an extra $50,000 in build costs, a 120-day schedule delay, or extra $500/month in lease costs? Sometimes one candidate stands so far above the rest that the additional cost and/or schedule impacts are obvious. Other times, the difference in quality can be difficult to defend. It is up to the RF Engineer to consider all the information, and make their best call. Though RF Engineering is most certainly steeped in science, often time the best RF Engineers are those that can balance the technical requirements of the project, with the practical requirements. They know when to take a stand, and when to compromise.

The site acquisition specialist must be conscious of all three of these when they identify possible candidate locations for the new site, and manage the expectations of the greater development team. Ultimately, the specialist will need to deliver the top three candidate sites that strike the best balance between these three often-opposing project requirements. By recognizing each of these factors, RF Engineers will better understand why Site Acquisition Managers are making the decisions they are making, which often causes the RF Engineer to revise the initial design in significant ways.

With all of those factors in mind and input from the RF Engineer, the Site Acquisition Manager will help select at least three viable candidate sites for the build, one of which will ultimately be selected by the team of stakeholders as the build location. If a lease has not already been formally executed at this point, the Site Acquisition Manager will work out the fine points of the lease with the landlord, while also conducting due diligence on the zoning, permitting and regulatory processes. Any money that is spent on the project prior to getting a signed lease is at risk of being a wasted investment, so a great deal of focus will be on getting this signed as early in the process as possible.

The Construction Manager and A&E team Enter the Picture
Once a site location is selected, the Construction Manager and A&E team become formally involved in the tower project, and that brings an entirely new set of considerations and variables into the project that may lead to revisions the RF Engineer must make to the design.

The A&E professional will work with the other parties involved to decide the best placement of the tower/pole, proposed and future loading on the tower/pole, layout of the compound, shelter/pad, ice bridge routing, location of utilities, etc. These details will be crucial for the completion of a formal set of drawings that will be used by the general contractor to construct the site.

Assuming the site walk doesn’t uncover any disqualifying issues, the A&E designer will generally get the green light to order a boundary survey of the selected land parcel and a geotechnical soils analysis for the tower foundation design. They will also get the go-ahead to start producing any zoning drawings, lease exhibits and photo simulations that may be required to keep the project on schedule.

The Construction Manager will be interested in many of the same things that concern the A&E designer, but will have additional concerns such as ease of site accessibility during construction, and for ongoing operations and maintenance. Will the site require 20 feet of gravel road from the main highway or, 3 miles of road grading over variable terrain? No new site build project has an unlimited capital budget, so it is up to the Construction Manager to make sure that the proposed location will fit within the project’s capital constraints.

Any issues related to the steps above are likely to require the RF Engineer to revisit the most recent version of the antenna design and make adjustments based on the physical realities imposed by the selected site, the legal height of the tower, the surrounding topography and more.

Regulatory/Municipal Entities Enter the Picture
The title of this section of the article is a misnomer because the reality is that good Site Acquisition Managers and Construction Managers will be making all of their decisions from the earliest stages of the project based on in-depth experience with the local and regional rules and regulations that impact tower builds. They will have ruled out sites that would spark prolonged regulatory battles and steered the project toward sites that are likely to have easier approval processes. This familiarity with the impact of zoning and regulations is one of the most important ways Site Acquisition Managers and Construction Managers can set up these projects for success. In effect, regulatory and zoning factors have been present since the beginning of this second phase of the new site build, but for the sake of this article I will talk about these entities as another set of actors that enter the stage, causing potential revisions to the tower design in the process.

No RF Engineer wants a project they have worked hard to shepherd through multiple iterations to stall near the finish line due to zoning/regulatory roadblocks. The expertise of the Site Acquisition Manager and Construction Manager are therefore critical to ensuring that tower projects are on a path to successfully navigate:

  • NEPA/environmental rules
  • SHPO/THPO requirements
  • FAA requirements
  • FCC requirements
  • Local zoning and permitting requirements, and more

There have been excellent, authoritative articles written by others on the topic of regulatory and zoning requirements for tower projects, including the resources that are on this site http://co-wa.org/regulatory/ maintained by the Colorado Wireless Association. I will defer to their excellent resources on this topic and simply mention that good Site Acquisition Managers and Construction Managers are basing many of their decisions on their knowledge of zoning and regulations, and their familiarity with what can and can’t get those seals of approval from municipal and regulatory entities. Teamwork matters on these projects, and the level of collaboration up to this point between the RF Engineer, Site Acquisition Manager and Construction Manager can pay off in big ways when the design faces scrutiny from municipal and regulatory bodies.

In the final part of this series of articles, I will discuss the last phase of new tower builds, which includes the actual construction of the tower and final configuration and testing before the site goes live.

Mar14_Centerline_John-KeatingAbout the Author
John C. Keating is an Executive Vice President at Centerline Solutions, the trusted turnkey provider of network services to the wireless telecommunications industry. In this role, John has responsibility for all professional services nationally, as well as construction services in the Southeast, Desert Southwest and New York state regions. His portfolio of services encompasses: RF Engineering; A&E; site acquisition; field technical services; Construction and network maintenance. John holds a B.S. in Electrical Engineering from the University of Colorado. With more than 20 years of experience in the wireless industry, he knows the ins and outs of managing all aspects of wireless Engineering, construction and operations.

Comments are closed.