The World’s Largest Metal Buried Bridge, Developed and Tested in Halifax Nova Scotia

With the continuous increase in infrastructure needs and the existing constrained public budgets there is an increased emphasis on cost effective innovative solutions to build Canadian infrastructure. Flexible buried bridges have been an integral part of the Canadian infrastructure for decades. Flexible buried bridges, also known as buried structures, are comprised of a corrugated metal structure surrounded by engineered backfill. Recognizing the need for this type of infrastructure, research was conducted at Dalhousie University on buried bridges. In 2018, the largest flexible buried bridge in the world was built for a transportation application in Dubai, UAE Utilizing the Type III Corrugation. The structure was designed and manufactured by Viacon Poland and has a span of 32.5 m and a rise of 9.5 m. In addition, the structure was epoxy coated for enhanced durability and longevity. The structure was instrumented with strain gauges and deflection prisms and readings were taken and analysed during backfilling. Over the last three decades, buried bridges have been increasingly used for large span applications, providing a more cost-effective alternative to conventional bridges (TRB Committees AFF70 and AFS 40, 2013). Maximum spans have increased making this technology a viable alternative for short and medium span bridges. The increased demand for these large span structures demonstrates the need to better understand performance under various loading conditions, and to develop appropriate design methodologies. Depending on the corrugation profile, corrugated metal structures are classified as shallow, deep corrugated, or deeper corrugated. Due to the higher flexural rigidity CAN/CSA-S6-14 assigns additional design considerations to deep-corrugated profiles.  The deepest corrugation profile was developed by Atlantic Industries in 2011. The profile has a pitch of 500 mm and rise of 237 mm (Williams et al. 2011), It is classified under CAN/CSA-G401-14 as Type III deep corrugated structural plate and as ‘deeper corrugation’ under CAN/CSA-S6-14.  The first structure built with this profile was in 2011 for a highway underpass in Newfoundland. Current equations in CAN/CSA-S6-14 are based mostly on finite element analysis by Duncan (1978). There is a need to re-examine the suitability of these equations for deep and very deep corrugated profiles and long span structures. Choi et al. (2004) compared the code equations to predictions by finite element analysis for spans up to 20 m. They found that code equations are valid though conservative. Vallee (2015) instrumented the Type III corrugation structure with strain gauges and deflection prisms. Vallee (2015) found that the code simplified method can be conservative for long span single radius arches and conservative for short span arches with relatively stiff plates. In this paper, the stresses, internal forces and deflections of the structure are presented. In addition, comparisons between field measurements and the CAN/CSA-S6-14 equations predictions are mad