Infrastructures
Highways and Interchanges

The St-Pierre Interchange is located in the south-west of Montreal at the junction of Route 138 to Highway A-20. Repair work on the five piles located under the access ramps has been completed in 2010.

In order to ensure safe works, general contractor GTS (Les Grands Travaux SOTER Inc.) approached Fraco for mast climbers. Ten units were moved to the project location, some mounted on free standing bases, others on ground bases. Installation and dismantling was carried out by Fraco technicians.

The repair work involved several phases: identification of damage areas; concrete chipping; cleaning; steel insertion and rebar reinforcement; formworks installation and concrete pouring. Telescopic booms could have been used for operations such as the identification of damage areas, but for other work GTS needed a stable and flexible access system that could support the weight of tools, hammers, workers and all materials needed to repair each pile. Because of their high load capacity and their large working area, Fraco's ACT-8 mastclimbers were chosen.

The size of the piles depends on their positioning under the ramps and their height varies between 20 and 28 m. Generally, the piles have a T-shape. Each pile needed two work platforms, positioned on the larger faces of the pile. The installation of short gateways between each mast climber allowed access to lateral faces. Other access systems were also necessary in the upper parts of each pile.

In order to guarantee the bearing capacity of piles, GTS followed an operation procedure prepared by MTQ (Ministry of Transport of Quebec). That procedure stipulated that each pile must be divided into four sections of work, each to be completed before the start of the next one. Thus, the repair works always started by lateral sections of the first quarter (section 1) of each pile (phase 1). Once the concrete was poured and lateral sections completed, GTS was repairing the axial sections located on each face of the pile in three steps (phase 2). The T-shape part represented the last section to be repaired. To do so, that part was divided into two sub-sections and the workers have repaired the diametrically opposed faces (phase 3 and 4) in one step.

Gerald Harnois, foreman at GTS, said that Fraco's platforms brought a dimension of comfort and safety, "Boom lifts have made the works difficult to complete because of their lack of stability. Our employees were expecting the same effect with the Fraco, but they realised the difference after few minutes of utilisation. These machines have really transformed their work environment."

Indeed, the concrete chipping phase requires hammers that can destabilize the boom lifts and other scaffoldings often used for repairing concrete piles. The length and scope of Fraco mastclimbers allow minimum moving around a pile. They offer an improved stability because of their simple, solid and safe anchoring system. In the case of the St-Peter Interchange, the work platforms had to be elevated over 20 meters high and masts had to be tied to each pile at every 3 and 15 meters from the ground. The result has been a comfortable and safe workspace that facilitated the execution of works.