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BASF and TRI Underground design new generation pits lids


The new generation pits lids designed by BASF and  TRI Underground can be found in projects around Australia and New Zealand, including by the Brisbane City Council, the Queensland Department for Transport and Main Roads and on the Caloundra to Sunshine Motorway Project.

When walking around busy city streets, we often spend a lot of time looking up and around, but do you ever stop and thinking about what lies beneath? The team at TRI Underground Australia, a family-owned Australian company operating out of Brisbane, Sydney and Melbourne spend more time than most pondering this question. 


As a local manufacturer who service the telecommunications, electrical and civil infrastructure markets, TRI Underground are especially passionate about pit lids. While pit lids – the access covers that can be found on roads and footpaths across cities – may seem unassuming, they play an important role in protecting the vast underground networks that control the traffic lights, internet and drainage that lie underneath our cities. 


Understanding the issues that were arising from only having a steel circular 600mm lid (known as a T60 pit lid) and other rectangular pit lids in the Main Roads and council networks in Queensland, Tri Underground in collaboration with BASF designed the TRI TUFF© composite lid.

“You may not think that a humble pit lid is a remarkable piece of engineering feat, however when you consider that the pit lid only weighs 10kg for safe and easy maintenance access (T60 model), yet is capable of supporting 8000kg, the importance of good design is clear,” explains Jeremy Gray, Business Manager from TRI Underground Australia.


When wanting to design this TRI TUFF© T60 lid, Tri Underground were seeking a lightweight material to act as an alternative to the durable, but extremely heavy and cumbersome, traditional pit lids manufactured with steel, concrete, cast iron and resin. In search of this perfect material, they reached out to leading global chemical company BASF for support.


“At BASF, we love a challenge, so when Tri Underground reached out to us with the ambition to design a pit lid that was durable enough to be mounted by pedestrians and light vehicles, yet lightweight enough to be manually handled on site without the use of mechanical lifting equipment and able to be installed within a matter of minutes, we were confident we would be able to help,” explains Kushal Mandavia, Senior BASF Account Manager.


“BASF’s Ultramid® moulding compounds proved to be the perfect solution to this challenge. The Ultramid® polyamide is perfect for injection moulding and extrusion and has high mechanical strength, stiffness, thermal stability and versatility in applications.”

The first collaboration saw BASF and Tri Underground produce the revolutionary Type 4 rectangular pit lid which was brought to market in 2011. The next collaboration produced a light weight, circular hybrid steel/composite lid, which was brought to market in 2012.


After these successful collaborations, both companies have seen the potential and decided to push the boundaries again to design a 1000mm wide circular pit lid (known as the T100) to join to TRI TUFF range in 2020. This pit lid is designed similarly to the T60 and is a major feat in engineering to allow such a wide single lid to support Class B load rating. These accomplishments have encouraged both companies to now look to design an even lighter, single piece lid – eliminating the need for steel structural support at all. 


“Our goal is to constantly remain innovative and to always find solutions to improve usability and safety on site,” says Jeremy 


These advances in the industry are made possible by both lid designs being produced using BASF’s unique CAE competence Ultrasim® to optimise the design of the material and improve it in every phase of its development.

“With Ultrasim® we can tailor components for specific requirements. We used this solution to help Tri Underground save costs in development and testing while shortening the time from R&D to market,” added Dr. Lynley Crawford, BASF Applications Development Manager.

Since these revolutionary lids have been brought to market, they have been adopted in projects around Australia and New Zealand, including by the Brisbane City Council, the Queensland Department for Transport and Main Roads and on the Caloundra to Sunshine Motorway Project.

“Our clients love these lids for a few reasons. First the lightweight material makes installing these on site much easier, mitigating against manual handling incidents. Secondly the material is non-conductive which is ideal for a live powered electrical pit and finally the lids are also lockable so they can be secured with a locking mechanism also designed by TRI Underground with BASF’s support,” continues Jeremy.

So next time you’re walking around an Australian city, don’t just look left and right before crossing the road, be sure to glance down too.


For more information on Tri Undergrounds innovative solutions, click here