We’ve asked our friend Henrik Kamstrup at Intelli Towers to write a regular column in the TowerXchange Journal, explaining the economics of evaluating and upgrading cell sites. Our first assignment to Henrik was to share a sample “Bill of Materials” and manpower expenditure to upgrade a tower for multiple tenancies, juxtaposing what is typically invested with how he thought it could be done more cost effectively. Here’s what Henrik came up with.
Is it worth while investing in evaluating existing towers?
Initially it is worthwhile investing in any tower due to the fact that the most important asset in most cases is the land and the lease contract. However, the main reason for avoiding a tower replacement is the extra cost and downtime when replacing the tower.
If possible, replacement should be avoided.
When evaluating existing towers, the owner or buyer often exposes the following challenges:
Unsafe towers due to missing bolts, missing bracing, vandalism or loose items
Missing bearing capacity for either the existing configuration or the future expected loading
Left unused cables or antennas
Corrosion
Lost as-build documentation
Most towers can be restored, upgraded and reinforced to the level of expectation, while a tower replacement with the existing height is rarely needed. Defining if the tower needs replacement, the following questions occur:
Remaining lifetime (i.e. how long a time do you need the tower on the site)?
Future need for antenna capacity?
Needed tower height?
Height extension is in many cases the ultimate reason for a complete tower replacement due to specific requirements with regards to deflection in the upper part of the tower. Deflection requirements can be close to impossible to physically overcome through reinforcement if the tower width itself is limited. In these cases, a tower swap is the most optimal solution unless a guyed, non-esthetic compound demanding solution can be accepted.
How to evaluate and upgrade newly acquired towers
Request a local contractor to measure the towers and determine the existing configuration incuding the possibility of dismantling existing unused cables and equipment in order to gain bearing capacity.
Based on the measurement information the towers should be analysed by a professional engineering company who use comprehensive tower software. This analysis will determine if the tower needs reinforcement and/or different levels of rectification in order to comply with the contractual obligations.
In case of reinforcement and/or rectification, the range of cost (including assessment and statics) varies from US$1,500-15,000 per site, which includes the potential reinforcement of the foundation as well.
The reinforcement of tubular towers (i.e. towers built with CHS profiles) is seldom done by a profile swap but by adding extra support points on each tower side and/or by adding ‘half shells’ as leg strengthening. A hypothetical ‘Bill of Materials’ for such a project is:
By reinforcing angular lattice towers the secondary bracing is either swapped to larger profiles or reinforcing flat bars are added. The leg profiles are either reinforced by adding larger angular profiles on top of the existing ones or by attaching flat bars.
The initial site assessment and following strength analysis determines the exact status of the tower and foundation. Mistakes in the site assessment report on site may result in an unnecessary reinforcement project and thereby wasted capex. Alternatively can a faulty site assessment report result in a non-rectified, unsafe tower.
Having a focus on supply of 100% correct site assessment reports, comprehensive knowledge of the latest national and international norms supplied by innovative structural engineering, the tower owner is able to reduce improvement capex significantly. Depending on the age of the towers, norm revisions also mean it may be possible to ‘upgrade’ the towers on paper only, where the cost is limited to only the site assessment and the static analysis.
About Intelli Towers Ltd. / KPR Consult A/S
Danish based Intelli Towers Ltd. is a joint venture with KPR Consult A/S, providing engineering innovative tower doctoring throughout the globe. Their services are mainly based on technical tower due diligence, tower strengthening and upgrading designs, royalty design production packages, tower knowledge teaching and emergency handling of critical structural situations
