In the public sector, 99.5% of the time, low price gets the job. Giving the job to the second bidder invites a lawsuit. The only way low price does not get the job is if the low bidder makes a mistake in his tender document paper work and his tender is declared informal. If a contractor submits a correct tender complete with bid bonds and performance bond, and he is low, he gets awarded the job. End of story, every time.
Budgets increase because of errors in the tender documents, unforeseen complications, scope creep, claims etc. Tender prices are ALWAYS enforced as are deadlines. Every time. However, the second there is a mistake in the design, there will be an extra cost associated with that extra and it costs more. Which is why I said, if you don't have an air tight design, you're in trouble.
The street cars are a bad example my friend. There are 2 sides to that story. The only side the public ever hears is the City's whining. Bbd wisely keeps its mouth SHUT. But the other side of the story is that the spec that the city wanted was almost impossible to achieve. Frist, the new street cars are 100 feet long and then some. The city's street car tracks date from the early 1900's when street cars were 25' long. The new cars had to be designed to turn on turning radii of 30'. So you tell me, how do you get a 100 foot long street car to turn on a radius of 30'? Secondly, the TTC switches have only one switch point instead of 2. So again, how do you get such a massive car to turn without blowing right out of the turn-out? Third, add in 0 height floors, all the other communication requirements of the TTC which were one of a kind. In a nutshell, no-one in the world had a street car that met the TTC's requirements. What you see rumbling down the streets are unique to the TTC and the first of their kind. Fourth, the delivery schedule was IMPOSSIBLE. It was dreaming in technicolour for Santa Claus to give you a zillion dollars. The TTC just said, "we want it our way, we want it on our deadline, and we don't care about whether it's possible or not, that's your problem". I can put out a contract that I want my new house built in 2 weeks, doesn't mean I can realistically get it. BBD signed because if they didn't sign, their competition would sign and you'd still have the same problem. This is how it works.
If you're talking about the street car platforms on St. Clair, they were designed and built to the old street car specification long before they even dreamed up the new ones BBD is making.