BurlOak
Senior Member
They should have done cut and cover! This is ridiculous. Cut and Cover would have save 5 years and maybe this is up and running in 2018! Same with the DRL. Hell cut and cover would all us to do all the Transit projects faster.
I am not sure, but I think the decision to use TBM was before they realized that boring could not be done under the existing subway lines. Essentially, these are 3 separate boring jobs each about 3 km long (the East one is a bit longer now that the launch site was moved to Don Mills). In those 3 kilometres, there are 3 or 4 stations (each with probably about a 200m cut excavation), plus a launch and extraction site. This means that even though TBM is used, about 1/3 of the total length is actually built with cut-and-cover. (If the station spacing on the DRL are closer, this could become over half).
I wonder why this is being built P3. Design–bid–build (design–tender) would require all design work for each step to be done before award. Design-Build could shorten the construction time a bit by only having preliminary design completed prior to tender, but the construction risk may be a bit higher. P3 (or AFP) is best suited for the entire process. There are a lot more risks for an "operate" contract so the Contractor needs to have enough flexibility to implement some inovative techniques to save enough money to compensate for the risks. I would have thought a real P3 contract would allow the contractor to propose different construction methods within certain contract constraints. It looks like they are using a combination of tendering methods and P3 is specified just to say it is being used, but not to actually try saving money or getting a better product.