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Can you say megaproject ...

As with many large infrastructure projects, the estimated cost of the I-35W replacement bridge rises and rises. How come public officials never over-estimate initial costs? (Perhaps a question for my Transport Policy class).

Articles from the Strib and PiPress:
Sticker shock: Bridge tab soars by $143 million

The cost of rebuilding the collapsed I-35W span is climbing

Comments

As a DOT employee, I can think of a few reasons:
A) understating costs increases early political feasibility. Just as in economics, there is a political sunk cost. Any sunk cost in politics may just be enough to keep the project going.
B)Constuction costs, including strucutral steel, structural concrete, asphalt and copper are increasing 3X faster than inflation at a minimum. People never account for inflation, which for some materials is hitting 20% per year.

C) E+C is always low. We now use a 30% contingency. That contingency doesn't match inflation.

D) Gold bricking. To make projects, especially large ones with well organized political forces, more palatable to the general public "gold bricks" get added. This may come in the form of asthetics, sound walls, environmental mitigation, bike/ped improvements, or in one recent caes here in Portland, $1M in community grants coming form the project budget.

By the way, you think thats bad, check out the Columbia River Crossing, the only bridge on the Interstate system with a lift span. That project is now $2-6 Billion!

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