It's a textbook example of
surplus extraction. The basic act of building the green line will bring in enough benefits to the city that it could be built for twice the price and still provide a net benefit, so the various 'stakeholders' will put in asks and requirements and scope increases and so on until the price has doubled. It still technically provides a benefit, so it'll get built, the local stakeholders get their goodies and who cares that we could have built twice as much instead. See also the underground Beltline section, see also the trenched West LRT at 45th Ave, and so on. If we built the Green Line at the price that Ottawa built their Confederation line for (adjusting for inflation), we'd be able to build 30 km instead of 20, up to 96 Ave N. If we built it at Edmonton Valley Line prices (again inflation adjusted), we'd be building 40 km instead of 30 and could do the whole line in one shot.
There's absolutely no need for this tunnel; it crosses a rail line that has about one train per hour, and increases access to basically nothing. But CP doesn't want to have the same disruption to their staff that they are absolutely fine with dishing out to everyone else, and they have the right of way, so they put in a demand in the negotiation. And there's no real pushback; in this case the legal framework around railroads in Canada is a fairly unique problem and one that should have been sorted out a long time ago by the feds, but there's plenty of other situations where it's just caving in to expand the scope and cost because that's easier than making a few people mad.
This area (400m circle from pedestrian tunnel) does not need millions of dollars of enhanced access.
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