that's true. i don't know denver that well. capitol hill (27.01) looks to be about 140 acres, with 3,800 dwelling units, so maybe close to 30.
i'm not suggesting that trains aren't justified - just that if any cities want to transcend the 5-15% mode share for transit, they need to entertain significantly higher densities around transit stations. otherwise these very expensive systems will continue to serve pretty small percentages of the population.
denver's expansion is great, but the development side has yet to come, as noted by the OP. i also agree that you wouldn't put a park-and-ride lot 1/2 mile away, but they shouldn't be placed immediately adjacent. a 3 or 4 minute walk is fine and those huge parking garages won't make sense when a neighborhood is truly built out.
as another bookend, most of san francisco's downtown residential districts permit (and encourage) a density of between 360 and 225 dwelling units per acre. those are on the lots themselves, so you have to take out streets and parks and other uses but a built-out primary residential neighborhood would still be in the 100 DUA range. there are many parts of the city that exceed this, even without lots of towers which are understandably suspect in many neighborhoods and economically questionable for certain housing types.
Originally Posted by mhays
No census tract in Denver has that sort of density, let alone any mile diameter. Hell, that's Brooklyn. Aside from inner cities, do any TOD districts in the country rise to that level? Are you suggesting that trains are rarely justified?
I believe that 50 DUA would be 24,000 units and 36,000 or so people, though the 1.5 might rise if districts like this were a big chunk of the housing stock, and multifamily became more common for families. If 10,000 were train riders that would be around 20,000 rides. That's not counting inbound commuters like those who work in your TOD. At that density, with a surface rail system where stations are cheap, you might as well do two stations.
While many people will walk a half-mile, the dropoff would be significant vs. people a block or two away. Pathetic as it is, people are lazy. And people who valued transit the most would probably locate closest to it. Someone like Cirrus might have typical numbers on this.