The increasing demand for complex infrastructure projects in density populated areas represents a major challenge for the construction industry, especially in view of the intimate interaction between construction activities and urban living. Modern society is pressing for innovative technical solutions to eliminate the safety, quality, environmental and management risks related to underground works. Diaphragm Walls are the retaining structure of choice for many of the most complex deep-foundation projects. Forming quality joints between the individual diaphragm wall panels is identified as the most significant weakness of the current process. Existing jointing techniques were designed for walls to 30m deep; modern diaphragm walls are typically significantly deeper. Beyond 30m, the options available are either technically and environmentally poor, or increasingly problematic, leading to sub-standard, defective joints.Foundation experts at CCMJ Systems have invented and patented the TTMJ (Tension Track Milled Joint) system which addresses the demand for a better diaphragm wall joint. This innovative new system offers the possibility to construct “perfect” joints to any depth irrespective of actual panel verticality. In addition it also allows for further innovation such as tension connections not currently possible.TREVI, CCMJ Systems and Arup have teamed up to complete development of the TTMJ system from present status to ‘ready for market’. ARUP is the leading specifier of diaphragm walling projects worldwide, CCMJ Systems is the inventor, TREVI will lead the team and is vastly experienced deep foundations specialist with a global presence.The expected outcome is a fully-functional and validated joint system providing a step change in diaphragm wall quality; ready for use across the deep foundations market.