>2. Project managing the build out of the whole thing at once would require a much larger organization, which would be more expensive >3. Building the whole th

>2. Project managing the build out of the whole thing at once would require a much larger organization, which would be more expensive >3. Building the whole thing at once would require a much large workforce and much more equipment, which would be more expensive. This doesn't work out in a linear model. You either hire N people for 2T years, or you hire 2N people for T years, either way a total cost of 2STN for a mean salary of S per year. It works the same way with project management. With equipment you might have something of a point, but not if the equipment is leased. You can point to nonlinearity, but then that looks like a weakness of the system. >4. Staging construction gives them the time to work out the details of the next phase while working on the current phase. The city is a moving target; details you work out today may not be true tomorrow. Worse, the different pieces of the system are interdependent: changing conditions may invalidate work already done, incurring additional costs. Ultimately, it seems like the only compelling reason on this list is (1), which itself points to a lack of overall strategy on the part of the government.