TMP Solutions, working with Essex Highways, have developed a non-metallic polymer lighting column embellishment kit as a safer and more economical alternative to traditional cast iron kits. These new polymer embellishments eliminate the structural safety issues caused by galvanic corrosion and make column testing quicker, safer and more economical as they don’t need to be removed during the testing procedure.
Why was this new type of embellishment kit developed?
There are over 4,000 lighting columns fitted with traditional cast iron embellishments in the county of Essex that are maintained by Essex Highways, a partnership between Ringway Jacobs and Essex County Council.
In early-2019 a lighting column with traditional cast iron embellishments was involved in a Road Traffic Incident (RTC) and was knocked down. On inspection, the column was found to have rusted through beneath the embellishment kit. This type of corrosion is called galvanic corrosion. If this column hadn’t been knocked down in the RTC, it is possible that it would have collapsed due to lack of structural integrity. This column was not the first, nor likely to be the last, that was potentially unsafe due to galvanic corrosion.
Columns with and without embellishments are routinely tested for their structural integrity. But testing columns with traditional cast iron embellishment kits is problematic. Often columns with traditional cast iron embellishments are marked “unable to test” as the cast iron interferes with the test. The only way to carry out the test properly is it to remove and refit the cast iron embellishments. In practice, this is not feasible due to time, access and compromised fixings.
Polymer Embellishment Kits
- To fit 76/140mm dia. columns
- Kit includes: Ladder Bar, Ring, Collar, Base and Fixings
- Made from polymer and finished in Gloss Black
- To fit 89 /168mm dia. columns
- Kit includes: Ring, Collar, Base and Fixings
- Made from polymer and finished in Gloss Black
What is galvanic corrosion, and why is it such a safety concern for street lighting engineers?
Galvanic corrosion, also known as bimetallic corrosion, is an electrochemical process whereby one metal corrodes in preference to another metal that it is in contact with through an electrolyte. The galvanic corrosion occurs when the two dissimilar metals are immersed in a conductive solution and are electrically connected. One metal (the cathode) is protected, while the other (the anode) is corroded. The rate of attack on the anode is accelerated, compared to the rate when the metal is uncoupled. In the case of lighting columns, the metal that corrodes is the steel column (the anode) when in contact with the cast iron embellishment (the cathode) and the electrolyte is primarily dog urine or saltwater.
Galvanic corrosion is such a safety concern because it happens out of view, behind the cast iron embellishment kit, weakening the column. Unfortunately, the most susceptible area of the column is the most dangerous – the base, and this is often where dog urine and saltwater collects the most. Street lighting columns can occasionally catastrophically fail due to corrosion, potentially causing severe injury to people and objects in the vicinity.
How was the solution developed?
Essex Highways had been searching for an alternative to cast iron embellishments for around four months before contacting TMP Solutions. TMP is more synonymous for traffic bollards rather than lighting columns. However, they are well known for developing innovative products and bringing them to market, after all, TMP did invent the retro-reflective rebound traffic bollard, so a non-metallic embellishment kit shouldn’t be too far of a stretch?
From the initial discussions in September 2019, it took just eight weeks to take the design from idea to prototype. This new non-metallic polymer embellishment kit was designed to be very similar in appearance to the traditional cast iron embellishments already installed on around 4,000 columns in the county.
For both Essex highways and TMP, it wasn’t just about designing a solution; it was about delivering innovation. The embellishment kit is made up of four parts: base, collar, ring and ladder bar. Producing all of these parts could have involved a lot of expensive tooling, but thanks to the talented design team at TMP, each part needs only one tool. Each part is made up of two identical pieces that interlock, providing not only strength and security but making installation quick and easy too.
Designing an embellishment kit that could be left in place during structural testing was a vital part of the brief. TMP worked with structural testing companies and listened to their feedback to ensure that these new polymer embellishments could indeed be left in situ and not cause any interference.
Installation takes just seconds, with each piece interlocking together. The fixings that hold the pieces together also secure the part to the column. As you will see from the videos on the TMP website, this fixing method is very secure, and the whole kit resistant to rotation and vandalism.
Sustainability is a crucial consideration in any new product design, and these new embellishment kits are no different. The manufacturing process produces almost no waste, and each embellishment can be removed and reused on a different column if needed.
A First for Essex - Polymer column embellishments installed in Colchester
In January 2020 the first 50 sets of TMP polymer embellishment kits were installed in and around Stockwell Street of the Dutch Quarter – Colchester, Essex.
The installation went without a hitch. The kits arrived ready to fit right out of the box, pre-painted in gloss black and complete with all the necessary fixings.
With the initial phase of the project completed successfully, the second phase of the larger 8-10m columns has been given the green light and installation is due to start in May 2020.
Feedback has been really positive with the pictures of the final installation speaking for themselves. Once installed, the TMP non-metallic embellishments look just like their traditional cast iron counterparts. But that’s where the similarities end. The TMP embellishments protect against galvanic corrosion caused by conventional cast iron. And unlike cast iron, the new polymer embellishment kits do not need to be removed when testing the structural integrity of the column – making the whole process safer, quicker and cheaper!
The TMP polymer embellishment kit is patent pending.