Tower Grillage - 4 Pile Solution

Unified tower grillages have either 4 or 8 piles depending on ground conditions and loading.
The photograph here shows a 4 pile grillage mounted on screw piles, ready to carry an SLP3 tower. Note how little space is required for a screw pile foundation and the lack of excavation or concrete. Reducing the number of companies involved, as well as the time and cost of installation.

Tower Grillage - 8 Pile Solution

For higher loadings, softer ground or more constrained sites, grillages with 8 piles can be required. As grillages are normally pre-assembled and the screw piles are often smaller, 8 pile solutions are still the fastest way to permanently install a tower.

FLI has a complete and proven range of off-the-shelf foundation designs, for all tower loadings, compound dimensions and ground conditions. 
Without using any concrete and without the need to remove any redundant foundations or move existing services, these solutions offer a single installation including both foundation and tower.

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Separate grillages for the legs of the largest towers.

For towers with wide footprints, often the larger modules of the T3a, some radar installations and transmission pylons, it is more efficient to replace the single grillage frame with individual feet for each leg.
The photograph shows one of these feet during install. In this instance, as the ground is rock, the grillage is mounted on raked micro-piles. The outer circle is re-usable form work for the grout.
As with all FLI foundations, this offers significant savings in installation time and enviromental impact, over the traditional concrete alternative.

T3a Heavy Duty Tower

Temporary Foundation Grillage

A Rapid deployment, reusable gravity grillage, transported by just two vehicles and bolted together on site. This free standing grillage does not use concrete blocks, so has a usable platform for cabinets and access with optional features incl. flooring, handrails, fencing, and steps.

More information on Temporary Towers

5G site upgrades over redundant mass concrete.

With a library of designs and in-house engineering for bespoke solutions, these grillage foundations can upgrade compounds for larger towers without removing the existing telecom tower foundation. They can also bridge existing services, fit into tight sites and upgrade existing high-load towers for multiple users. Entire tower foundations are installed in as little as two shifts and easily removed and recycled at end of life.

Here, the FLI solution is bridging the old concrete tower foundation with screw piles and a  grillage. 

Grillage platforms for site upgrades & sloping sites. 

Enabling the use of the smallest compounds and sites with slopes or congested services. Platforms for cabinets and access can be installed above the grillage foundation.

These platforms can integrate with both new and existing telecom tower foundations and FLI has off-the-shelf designs for both tower and monopole installations.

Monopole Grillage - 4 Pile Solutions

Monopoles with lower loadings often only require 4 piles.
Screw pile and grillage foundations are an efficient way to support monopole towers and cabinets on embankments, cuttings and soft made-up ground.
Grillages can be designed to span existing concrete bases or bridge buried services.

The photograph shows an installation from the GSM-r network. These were often at small sites along railway lines, with very limited access (without closing the line) and so lightweight, folding grillages were developed, to help installation without increasing time on site.

Monopole Grillage - 8 Pile Solutions

For monopoles with higher loadings, including FLI's Telecoms Trees, there are 8 pile foundations.
This new range of radial grillages offer fast, efficient foundation install, for  large monopoles in the smallest existing compounds. Because Screw piles resist the overturning forces of the tower using the helicies deep underground, rather than with the weight of mass concrete on the surface, the foundation can be much narrower, enabling upgrades without having to extend the site.
Avoiding using concrete also turns foundation and monopole installation into a single operation, saving time. With aditional savings on site upgrades, as legacy mass concrete can be left in situ and existing services can be bridged over without downtime.

Adjustable Streetworks Grillage

Each arm can be adjusted on site for both length and angle. This enables installation around buried services, without GI or trial pits prior to install day. This off-the-shelf product can also be adjusted to fit awkward shaped sites, removing the need for bespoke solutions.
All parts of the foundation are hand carryable and the piles are usually Ø76mm, which allows for hand-held kit or very small plant suitable for the most crowded urban areas.

A range of interface plates are available for poles, cabinets and advertising signage.

Towers & Monopoles On Sloping Sites

Using a steel foundation instead of concrete is ideal for installing towers, monopoles and access platforms on the steepest slopes and the soft, made-up ground of embankments on the rail and road networks. These deep foundations with their grillages and staging, carry the loading well below any challenging topography and completely avoid the problems facing concrete on these sites.

81% Lower Carbon Footprint

Screw piles combined with a steel grillage foundation offer a substantial carbon saving over traditional concrete raft foundations, on both material and installation.

The 81% saving example refers to a foundation for a 30m ATS1301 tower.

Assumptions:

• Concrete and spoil lorries travel 25 miles.
• Concrete rafts remain in place at end of life (typical in telecoms).
• Structural steel is recycled in an electric arc furnace.

99% of structural steel sections are recovered and recycled. Unlike a mass concrete foundation which can only be downcycled, a steel grillage foundation can be fully recycled. Screw piles can also be fully removed, unscrewing from the ground faster than they were installed.

The recycling of embodied carbon is where most of the saving is made. However, with no spoil away, fewer HGVs to site and fewer days on site, the installation process itself also delivers a 68% C02 saving over a mass concrete solution.

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