Quote:
Originally Posted by Novacek
Thanks
That really surprises me though, that with non-double tracked and limited sidings, and slow freight trains (that would take over an hour to travel through the corridor) that they'd run at the same time in the passenger corridor.
Or maybe they mean this is necessary but not sufficient, that they still need full double tracking to do that (in the future).
Or "at the same time" means passenger service in the passenger corridor, and freight at the same time west of Leander and on the green line.
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Is double tracking the entire corridor really needed? I don't think so.
I'm pretty sure they will be able to squeeze in a slow freight train when the passenger train frequencies halve - during mid-day between the morning and evening peaks.
Simple explanation follows:
P = Passenger train, F = Freight trains
P P P P P P P (15 minute headways) vs P F P F P F P (30 minute headways)
As for the slower speeds of the freight trains, it's not maximum speeds that counts when considering traveling over the entire corridor, it's average speeds that counts. Faster passenger trains making frequent stops to alight and board passengers at every station along the way average slower speeds than slower freight trains that aren't stopping along the way.
Explanation follows:
The rail corridor from Leander to downtown Austin is 32 miles in length. Let's simplify it somewhat to make the math easier to 30 miles....
A train going a steady 30 mph (freight train speed) will take an hour to go 30 miles.
A passenger train averaging 30 mph while speeding up to 60 mph and slowing down to a complete stop at stations will take the same hour to go the same 30 miles.
So what is the average speed of Capital Metrorail Red Line trains?
Using Wiki for data:
https://en.wikipedia.org/wiki/Capital_MetroRail
Here's the math = 32 miles / 62 minutes x 60 minutes / hour = 30.96 mph
The passenger trains may reach a maximum speed of 60 mph or even 79 mph, but they only average approximately 31 mph over those 32 miles.
Therefore, I suggest they will not need to double track the entire corridor. They wouldn't need freight train long passing sidings either because the existing passenger train long passing sidings will do as long as two freight trains don't meet. If you want two freight trains to meet , you'll only need one freight train long passing sidings so they can meet about half way along the corridor. Scheduling all the trains to a schedule solves all the other meets.