A suicide barrier was constructed along the Bloor viaduct in Toronto (official name is the Prince Edward Viaduct) and help line phones were installed at each end of the bridge. It has been in place for about 4 years now. The name of this barrier is "The Luminous Veil".
Apparently the number of suicides on this bridge since the net was erected has been zero.
Here's some lyrics on the subject from the BareNakedLadies:
Near where I live there's a viaduct
Where people jump when they're out of luck
Raining down on the cars and trucks below
They've put a net there to catch their fall
Like that'll stop anyone at all
What they don't know is when nature calls, you go
Bloor viaduct "Luminous Veil" a $6 million life saver - Opinions
Luminous Veil - Wikipedia, the free encyclopedia
Prince Edward Viaduct