Union Station approach - what is sharpest curve allowed?

[Jenner]

In looking at the master plan for US, south track 2 will be realigned a little to handle a 12 degree curve into the parking area at the concourse. I was looking at their diagrams, and there seems to be a path available to make track 2 curve sooner near Harrison St., right where the old post office "starts" at the south end - assuming no obstructions from pillars of the old post office. The master plan has new track alignments for the removal of the baggage platforms on the south side platforms.

In any case, my thought is that if you can straighten out track 2 a bit more, you can eventually make tracks 4,6,8 straighter, which allows more cars on the trains, thereby increasing capacity. However, by moving the tracks in this manner, the alignment would give track 2 a sharper turn into the concourse, maybe 25 degrees. I don't think this is much of a problem, given that trains are probably going 20mph into the concourse, but I wasn't sure if there are any engineering rules which could prohibit certain angles for rail curves. So the question is, what is the maximum allowed curve on approach into the concourse for the Metra trains?

[doepack]

I'm not sure of the maximum curvature that Metra allows for access to its downtown terminals, but keep in mind that CUS track 2 is already long enough to berth 11 car Metra consists. Any future modifications may result in modest capacity increases for tracks 2 thru 8; and it may be enough to enable Metra to store at least a partial consist on one of these tracks as is done on the north side during midday. Given the proximity of the 14th St. yard to the south end, it's unlikely they'd do that, but I learned long ago that trying to guess Metra's intentions and actions on certain matters is foolish. We'll see...

IMO, modifying both the north and south concourse areas to ease overcrowding during service disruptions while extending the platforms along terminal tracks 6/8 & 10/12 outward into the area where the (current) baggage platforms are to be eliminated will be the most important benefits of the renovations, IMO. It should make the flow of people in and out so much better, and enable more efficient separation between Amtrak and Metra passengers...