Complex geosynthetic skewing around piles by Reinforced Earth

The Hurdman East Overpass project is a Light Rail Transit (LRT) bridge overpass carrying a light rail vehicle over a pedestrian pathway. This structure is part of a large infrastructure project in Ottawa, Ontario, which involves the construction of an LRT system to span the city. This project will improve congestion on local highways as well as create a more efficient and environmentally friendly transit system. This project is owned by the City of Ottawa, who awarded the package to the Rideau Transit Group (RTGE) consisting of a consortium including Canadian and International entities. The construction of the false abutment with Mechanically Stabilized Earth (MSE) structures was completed in late 2015, with approximately 300 m² of MSE walls distributed between the two abutments. The Ottawa Light Rail Transit (OLRT) design build project was awarded to RTGE in February 2013 and shortly thereafter preliminary construction began.


In order to accommodate the need for transitioning of the Bus Rapid Transitway system already in place to the future Confederation Line, a major overhaul of Highway 417 took place which saw the highway being expanded to counter the negative impact that construction may have on the existing transit system. The OLRT program will decrease air and noise pollution by emitting minimal sound (as compared to the diesel buses which are now used) and running off of strictly electricity. This project includes a tunnel through downtown Ottawa which is a major infrastructure accomplishment and will be the longest of all the individual projects.


Specifications for this project limited the soil reinforcement strictly to geosynthetics. In addition, the selected MSE wall system implements the use of strap elements as soil reinforcement in conjunction with inclusions. An example of the challenges faced during design and construction is the H-Piles for the false abutments which are embedded into the Reinforced Earth zone. The soil reinforcement was required to avoid these obstacles while simultaneously resisting the horizontal forces coming from the superstructure. The Hurdman East Overpass bridge will be supported by 14 H-Piles and Reinforced Earth false abutments. The inclusion of the H-Piles creates the need for a MSE soil reinforcement skew system which differentiates this project from others of similar scope.