1. Lower initial construction cost and faster pier erection
2. Better architectural finish and reduced maintenance requirements
3. Harsh winter climate requiring factory-controlled casting conditions
4. Environmental restrictions limiting on-site concrete operations

Explanation

Montreal's harsh winters (temperatures below -20°C for extended periods) make quality concrete placement challenging. Factory-controlled precast production ensures:

Consistent concrete quality and strength development
Protection from freeze-thaw during curing
Year-round production capability
Better quality control and reduced winter construction delays
The St. Lawrence Seaway navigation requirements also favored rapid span erection using launching gantries.

Learning Resources:
CSA S6-19 Canadian Highway Bridge Design Code - Cold weather concreting requirements
PCI Cold Weather Concreting Guidelines - Quality control for precast segmental production