As soon as the government gets involved in a public construction/renovation project costs sky rocket. I can only attribute it to bureaucracy, corruption, and indifference since the tax payers pockets are endless. Contractors all have to be Unionized (good/bad?), it seems there is no urgency to do anything quickly or in a cost effective manner.
When you look at the renovations on the subway taking place at Royal York Station, it's comical. The project shouldn't take more than 3-6 months but it seems they want to drag out the job so they can retire after it's complete in 20-30 years. Runnymede Station took about 5 years and I'm not sure they're finished. Something like pulling up 200 sq/ft of tile can take a 1-2 months of 2-3 guys working 8 hours a day.
This is what happens when there is corruption with no oversight and the source of payment is the tax payers pocket.