Why can't MetroRail be extended to Seaholm?
Just thought I'd better write this down since I composed it twice only to lose most of it due to a stupid typepad/austinist interaction. Guys? Don't use AJAX where input can be lost, OK?
In the annals of Transit Stupidity, this will be one of the top entries. Read on.
MetroRail can't feasibly be extended to Seaholm because it would have to run on 4th street all the way to the creek, and then get a brand new, very expensive, diagonal (long) bridge to transition to the 3rd street alignment the Seaholm project roughly abuts. (See image, source city's OnTrack newsletter; click if it appears cut off). The DMUs we picked are too heavy and clunky to corner in the intersections available before that - so despite the fact that 3rd was the preferred rail corridor, we're stuck with tearing up a ton of 4th street to do this project or just cutting through the middle of a downtown block - not gonna happen. (Go to page 3 of that PDF). Combine that with the fact that the Feds would be extremely unlikely to kick in one lousy penny due to low ridership and low cost/benefit rating for service like this, and it's not going to happen. Note that Capital Metro didn't get any federal funding for the commuter rail starter line, fairly obviously because of extremely low ridership projections.
Note that all of the "Seaholm and rail" planning from the people who actually have any say on this issue has to do with a streetcar connection to UP at the Seaholm site, NOT any extension of the starter line west to there.
And, even if by some miracle we did get commuter rail to Seaholm, it couldn't continue up or down that Union Pacific line, because the DMU is not, by rule, allowed to run with freight rail. Cap Metro solved this by getting a "temporal separation" agreement ratified which promises that freight will only run in the wee hours of the morning, but UP would never agree to this. So, ironically, this DMU that we picked because it's supposed to be so much cheaper than real light rail is too heavy to run where we need it to run in the street, but too light to run on existing rail which might be better suited for transit-oriented development opportunities than our starter line is.
Who screwed up here? Well, of course, Capital Metro did, if you assume that they cared about rail transit (I don't think they do; I think their post-Karen-Rae leadership wanted to prove, with Mike Krusee's assistance, that "rail doesn't work"). But the more correct answer is: the credulous center-city pro-rail-transit people who assumed that we could 'fix' the plan by adding things to it later despite commentary all along from yours truly that it wasn't going to be possible.
Addendum: I finally found the full Seaholm station report. According to them, the DMU Capital Metro is using for the starter service has a turning radius of 300', which is way too high, but even at the more often heard 135' or so, it will, as I expected, never be able to turn a corner in the street (see city's OnTrack newsletter link above for more on that). The east-to-south curve being preserved only supports a turning radius of 100' - meaning these DMUs will never be able to cross the river from here to South Austin. If we somehow convinced UP to abandon freight operations on this line, there is no physical obstacle to DMUs continuing west and then north up the Mopac line, but again, for all the practical reasons detailed above and then some, this will never happen.