• Washington to Baltimore: maglev or hyperloop?

  • General discussion of passenger rail systems not otherwise covered in the specific forums in this category, including high speed rail.
General discussion of passenger rail systems not otherwise covered in the specific forums in this category, including high speed rail.

Moderators: mtuandrew, gprimr1

  by John_Perkowski
 
I just rode on a TGV in France. Given this distance, are we discussing a nonstop run? Even a 286kmph TGV needs acceleration and deceleration distance. If there are stops, that will increase the transit time to the speed of current Amtrak.
lpetrich wrote: Fri Dec 08, 2023 8:34 am It's about 40 mi / 60 km between DC and Balto. At 200 mph / 320 km/h, the travel time would be 11 minutes. By comparison:
  • Amtrak: 30 - 40 min
  • MARC: 40 - 60 min
So I think that it would be hard to justify such a maglev line.

The Hyperloop is essentially a maglev vactrain, and that's even worse.
  by lpetrich
 
It was hard for me to find numbers on acceleration of high-speed trains, but I've found TGV POS - Wikipedia -- its acceleration numbers have "citation needed" on them.
≥1.7 km/(h⋅s) (1.1 mph/s)(0–100 km/h (0–62 mph)),
0.35 km/(h⋅s) (0.22 mph/s) (at 320 km/h (199 mph)), from 0 to 320 km/h (0 to 199 mph) within 5 minutes 20 seconds and 18 km (11.2 mi
That's about 0.048 g or 1/20 g, where g is the acceleration of gravity on the Earth's surface.

To get to 300 km/h at 1.7 km/h/s, one needs 3 minutes, and a distance of 7.4 km. Since one must decelerate by that amount to stop, that means a combined distance of nearly 15 km. That's about 1/4 the Balto-DC distance, with an extra travel time of 3 minutes, about 1/4 of the travel time.

The math:

t = time, d = distance, v = velocity, a = acceleration
v = a*t
d = (1/2)*a*t^2
  by STrRedWolf
 
lpetrich wrote: Fri Dec 08, 2023 8:34 am It's about 40 mi / 60 km between DC and Balto. At 200 mph / 320 km/h, the travel time would be 11 minutes. By comparison:
  • Amtrak: 30 - 40 min
  • MARC: 40 - 60 min
So I think that it would be hard to justify such a maglev line.

The Hyperloop is essentially a maglev vactrain, and that's even worse.
Hmmm... (mind the metric for a bit, I'll reconvert it back)
  • 45 mph from 2nd street to almost the 9th street NE: 1.24 km
  • 95 mph there to past Bladensberg Rd NE (US 1 Alt): 2.74 km
  • 125 mph that point to Baltimore near Frederick Avenue: 53.19 km
  • There's a mix that starts here but the average looks to be more 90 mph, from that street to West Baltimore: 2.1 km
  • From here to...
Okay, lets switch over to the proposed alignment of the new tunnel. It's supposedly good for at least 70 mph but they're saying 100 mph. Lets assume the average along this roughly 2.7 mile (4.35 km) stretch is 70. OpenRailwayMap says the MAS on the eastern ("north") end is 30 mph, and we'll give some leeway on the other end at 110 mph since they're going to straighten things out around West Baltimore and rebuild the station there. We'll bump up speeds on the southern approach here as well, so:
  • 45 mph from 2nd street to almost the 9th street NE: 1.24 km or 0.77 mi, or just over a minute.
  • 95 mph there to past Bladensberg Rd NE (US 1 Alt): 2.74 km or 1.70 mi, or another minute.
  • 125 mph that point to Baltimore and southern end of FD Tunnel: 55.29 km or 34.26 mi, or 16 and a half minutes.
  • 70 mph on average to the CHARLES interlock: 4.35 km or 2.7 mi, or 2 and a third minutes.
So a non-stop Acela would take 22 minutes roughly to make a DC to Baltimore trip, with the new tunnel.

And they're claiming 11 minutes non-stop?
  by lpetrich
 
STrRedWolf wrote: Sat Dec 09, 2023 12:50 pm So a non-stop Acela would take 22 minutes roughly to make a DC to Baltimore trip, with the new tunnel.

And they're claiming 11 minutes non-stop?
That's my calculation for 200 mph / 320 km/h over all the line's length, with instantaneous acceleration.
  by STrRedWolf
 
lpetrich wrote: Sat Dec 09, 2023 5:36 pm
STrRedWolf wrote: Sat Dec 09, 2023 12:50 pm So a non-stop Acela would take 22 minutes roughly to make a DC to Baltimore trip, with the new tunnel.

And they're claiming 11 minutes non-stop?
That's my calculation for 200 mph / 320 km/h over all the line's length, with instantaneous acceleration.
Lets see with some of the above work... 75% of the line at 200 mph would be 8.25 minutes, add another 5.5 for acceleration/decelleration on a linear scale... about 14 minutes.

14 vs 22... that's starting to put a lot of effort into little gain.
  by John_Perkowski
 
Admin note: Hyperloop One Inc has closed its doors. This topic is now moot.

Thread on Hyperloop one closing: hyperloop-inc-end-of-the-line-t176348.html
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