2015 Minnesota State Rail Plan

Roads - Rails - Sidewalks - Bikeways
froggie
Rice Park
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Re: 2015 Minnesota State Rail Plan

Postby froggie » April 25th, 2016, 5:51 am

Another thing to consider: there is more than one type of curvature when it comes to both rail and road. Not only is there the horizontal curvature, but also vertical. Vertical changes on a horizontal curve are usually referred to as superelevation.

mattaudio
Stone Arch Bridge
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Re: 2015 Minnesota State Rail Plan

Postby mattaudio » July 5th, 2016, 1:11 pm

So I was looking through this plan once again. And I saw two items that fascinated me. One is a replacement of the BNSF lift bridge at Prescott ($50 million), and the other is the replacement of the CP lift bridge at Hastings ($90 million). But both of these structures are under 35 years old! Why were they built without double tracking, despite both being on such important mainlines?

SteveXC500
Nicollet Mall
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Re: 2015 Minnesota State Rail Plan

Postby SteveXC500 » July 5th, 2016, 1:51 pm

Important mainlines, yes. How often is there congestion because of bridges being single-tracked? Cost difference in single v. double?

JT$
City Center
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Re: 2015 Minnesota State Rail Plan

Postby JT$ » July 6th, 2016, 12:27 pm

mattaudio wrote:So I was looking through this plan once again. And I saw two items that fascinated me. One is a replacement of the BNSF lift bridge at Prescott ($50 million), and the other is the replacement of the CP lift bridge at Hastings ($90 million). But both of these structures are under 35 years old! Why were they built without double tracking, despite both being on such important mainlines?
Not enough traffic to warrant the added cost I would imagine.

mattaudio
Stone Arch Bridge
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Re: 2015 Minnesota State Rail Plan

Postby mattaudio » July 6th, 2016, 12:48 pm

But isn't it an even greater cost to consider heavily modifying, and presumably replacing the main lift spans, compared to if they just built these with capacity up front? Though the original swing bridges built by the Q and the Milwaukee Road, both removed in the 80s, were both single track despite these two critical main lines being double tracked throughout most of their histories.

Anyways, any news on the rebuild of the ex-CGW (Robert Street) lift bridge replacement the U.P. is planning? I saw soil and engineering work taking place this spring and I thought construction was supposed to start in 2016.

mulad
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Re: 2015 Minnesota State Rail Plan

Postby mulad » July 6th, 2016, 7:39 pm

Single track is a problem that is more or less proportional to the length of the track segments. If you have 50 miles of single track with no sidings, then you're heavily restrained on line capacity (for bi-directional traffic), but railroads often build double-track (or sidings) right up to each end of a bridge. Traffic can queue up right near each end and be more or less ready to go as soon as the last train gets through. The single-track segment for the Prescott bridge is less that 1,900 feet, so there can be quite a few trains moving through over a given period of time.

Of course, freight railroads keep pushing their trains to be longer and heavier, so there's a problem of accelerating to fast enough speed to get over a bridge in a reasonable amount of time (and bridges are often speed-restricted anyway). Having parallel bridges would allow the trains to move across them at higher speed (though it may still be fairly slow).

I'm curious whether these would really be replacements or if they'd just be new bridges parallel to the existing ones. That's what had been planned for the Hastings crossing in the Southeast Metro study, but plans can change.

talindsay
Wells Fargo Center
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Re: 2015 Minnesota State Rail Plan

Postby talindsay » July 8th, 2016, 12:02 pm

Matt, I think you're forgetting that 35 years ago freight rail was shrinking and passenger rail appeared all but dead. The massive influx of goods from China, along with the explosion (no pun intended) in oil trains from domestic ethanol and Bakken production, was completely unforeseen and not being planned for. If in 1980 the demand wasn't high enough to warrant double tracking, there was no reason to believe it ever would be. They were wrong, yes, but they made an absolutely correct choice given what they knew at the time.


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