Much of Canada's existing infrastructure was constructed during the 1950s, 1960s and 1970s. And, given the fact that the useful life of many of the country's physical structures runs up to only four or five decades, a significant share of assets would be already ripe for replacement or rapidly approaching the end of their cycle. However, there have been a number of developments on both the supply and demand sides of the equation that have acted to accelerate the amount of wear and tear on many public assets over the past few decades.