Replacing the Piled Foundations of the Houphouët-Boigny Bridge in Abidjan Cote d’Ivoire

Due to historical ground movement, increased traffic levels, and general degradation, this important road and rail bridge which provides an essential link between the interior of the country and the Port of Abidjan, required significant repair and reinforcement. This included strengthening the pre-stressed concrete box girders and replacement of the piled foundations. Replacement piles had to be adjacent to, and no longer than, the existing piles to not compromise the stability of the operational bridge during the works. The underlying geology, however, meant that the pile loads had to be predominantly transferred into the ground through end bearing. Rather than installing a greater number of piles or larger diameter piles, innovative thinking changed the usual mind-set of designing the piles to the prevailing ground conditions, to designing the ground conditions to suit the piles. Jet grouted columns were installed beneath the toes of the new piles to increase the bearing capacity of the ground. This significantly contributed to the sustainability of the project and reduced carbon emissions through saving concrete, steel, plus transportation and disposal of spoil.