Re: I thought high speed rail didn't use steep grades on short segments precisely to avoid the rollercoaster effect
Author: FUD
Date: 08-05-2023 - 16:20

The key point isn't the grade so much as the vertical curve. You want to avoid making the train occupants pull Gs, especially negative and lateral. The Gs happens when you change profile, not on the grade itself. With a long enough transition, those short grades to a bridge or viaduct are fine. I don't see them being long enough to take more than 10-20 mph off a train using them, anyway. A longer 1% grade might have a greater effect on diesels, especially coming off some kind of speed restriction (like a station). So there may be a balancing act in the design for that.

Then, of course, if there are some minor Gs pulled with the HS equipment, it'll be at 150+ mph speeds. The fastest a diesel Amtrak can go is about 125, and 90-110 is more likely. So ... the short grades in the Valley aren't going to be much of a bother.

Where the 4% gets serious is on a longer grade, like over the mountains. There, even a true HSR trainset is likely to be unable to maintain full speed. Minimizing the speed drop is one reason why Desert Xpress, revised to eliminate a tunnel at Mountain Pass by Brightline West, has to use fully electrified HSR trainsets. And even so, speeds on the steep grades won't be that high - maybe as much as 70-80 mph, but probably not by much, due as much to the curves, following the freeway, as to the grade. IOW, about the average speed cars and light trucks currently move on I-15, absent a traffic jam, when climbing Cajon Pass; a substantial minority exceeds 100, and a much larger minority does so if traffic allows once out in the desert.



Subject Written By Date/Time (PST)
  Event: Complete California High-Speed Rail in Five Years? Commenter 08-02-2023 - 20:53
  Re: Event: Complete California High-Speed Rail in Five Years? LMAO... I love the developer and contractor funded new urbanist "front groups" for their optimism.... BOB2 08-03-2023 - 09:18
  Re: Event: Complete California High-Speed Rail in Five Years? LMAO... I love the developer and contractor funded new urbanist "front groups" for their optimism.... John Bruce 08-03-2023 - 14:21
  Re: Event: Complete California High-Speed Rail in Five Years? LMAO... I love the developer and contractor funded new urbanist "front groups" for their optimism.... John Bruce 08-03-2023 - 14:36
  Re: Event: Complete California High-Speed Rail in Five Years? LMAO... I love the developer and contractor funded new urbanist "front groups" for their optimism.... FUD 08-03-2023 - 15:38
  Re: Event: Complete California High-Speed Rail in Five Years? LMAO... I love the developer and contractor funded new urbanist "front groups" for their optimism.... Beaver Cleaver 08-03-2023 - 22:59
  Re: Event: Complete California High-Speed Rail in Five Years? LMAO... I love the developer and contractor funded new urbanist "front groups" for their optimism.... FUD 08-03-2023 - 15:45
  Rumor was CHSR would poison pill the segment by building to standards that can't support the weight of traditional diesels or dual modes But 4% grades are not a problem 08-03-2023 - 19:46
  Re: Rumor was CHSR would poison pill the segment by building to standards that can't support the weight of traditional diesels or dual modes John Bruce 08-04-2023 - 10:04
  Re: Rumor was CHSR would poison pill the segment by building to standards that can't support the weight of traditional diesels or dual modes Clem 08-04-2023 - 19:43
  Re: Rumor was CHSR would poison pill the segment by building to standards that can't support the weight of traditional diesels or dual modes John Bruce 08-05-2023 - 07:27
  Re: Rumor was CHSR would poison pill the segment by building to standards that can't support the weight of traditional diesels or dual modes Transportation Planner 08-05-2023 - 08:15
  Re: Rumor was CHSR would poison pill the segment by building to standards that can't support the weight of traditional diesels or dual modes FUD 08-05-2023 - 09:12
  Re: Rumor was CHSR would poison pill the segment by building to standards that can't support the weight of traditional diesels or dual modes FUD 08-05-2023 - 09:13
  Re: Rumor was CHSR would poison pill the segment by building to standards that can't support the weight of traditional diesels or dual modes Transportation Planner 08-05-2023 - 10:28
  Re: Rumor was CHSR would poison pill the segment by building to standards that can't support the weight of traditional diesels or dual modes John Bruce 08-05-2023 - 09:14
  BOB2, can you weigh in on this "Short 4% grades will kill travel time" nonsense? Jimmie 08-05-2023 - 14:19
  I thought high speed rail didn't use steep grades on short segments precisely to avoid the rollercoaster effect Jimmie 08-05-2023 - 14:22
  Re: I thought high speed rail didn't use steep grades on short segments precisely to avoid the rollercoaster effect John Bruce 08-05-2023 - 15:15
  Re: I thought high speed rail didn't use steep grades on short segments precisely to avoid the rollercoaster effect FUD 08-05-2023 - 16:20
  Re: I thought high speed rail didn't use steep grades on short segments precisely to avoid the rollercoaster effect John Bruce 08-06-2023 - 07:14
  Re: I thought high speed rail didn't use steep grades on short segments precisely to avoid the rollercoaster effect FUD 08-06-2023 - 08:46
  Re: BOB2, can you weigh in on this? Are you sure? No, but no short four percent segment is going ot bring a 125 train down to 40 mph. in a half a mile of 4% grade. BOB2 08-05-2023 - 19:10
  Re: BOB2, can you weigh in on this? Are you sure? No, but no short four percent segment is going ot bring a 125 train down to 40 mph. in a half a mile of 4% grade. Blathering bob 08-06-2023 - 09:09
  Re: BOB2, can you weigh in on this? Are you sure? No, but no short four percent segment is going ot bring a 125 train down to 40 mph. in a half a mile of 4% grade. BOB2 08-06-2023 - 09:29
  Re: Hey look the doped up latent repressed mentally ill troll is posing as BOB2 again... BOB2 08-06-2023 - 10:36
  Re: BOB2, can you weigh in on this? Are you sure? No, but no short four percent segment is going ot bring a 125 train down to 40 mph. in a half a mile of 4% grade. Chris Walker 08-06-2023 - 14:46
  Re: Well, about the incident at the westbound Niland distant signal.... BOB2 08-06-2023 - 15:29
  Re: Well, about the incident at the westbound Niland distant signal.... BLOB222 08-07-2023 - 09:35
  Re: Well, about the incident at the westbound Niland distant signal.... Chris Walker 08-07-2023 - 14:27
  Re: Well, about dynamiters.... And trolls... BOB2 08-07-2023 - 17:57
  Re: Well, about the incident at the westbound Niland distant signal.... Dr Zarkoff 08-07-2023 - 20:36
  Re: Well, about the incident at the westbound Niland distant signal.... Chris Walker 08-08-2023 - 04:32
  Re: As usual, I only knew the effects... The good Doctor knew the cause.... BOB2 08-08-2023 - 06:52
  Re: Well, about the incident at the westbound Niland distant signal.... Dr Zarkoff 08-08-2023 - 13:42
  Re: Well, about the incident at the westbound Niland distant signal.... Chris Walker 08-08-2023 - 14:56
  Re: Well, about the incident at the westbound Niland distant signal.... Dr Zarkoff 08-08-2023 - 15:50
  Re: Well, about the incident at the westbound Niland distant signal.... Chris Walker 08-08-2023 - 18:49
  Re: Well, about the incident at the westbound Niland distant signal.... Dr Zarkoff 08-08-2023 - 23:59
  Re: Well, about the F3 Dr. Z. Chris Walker 08-12-2023 - 02:59
  Re: Well, about the F3 Dr. Z. Dr Zarkoff 08-12-2023 - 12:02
  Re: Well, about the F3 Dr. Z. Chris Walker 08-12-2023 - 18:01
  Re: Well, about the F3 Dr. Z. Dr Zarkoff 08-12-2023 - 19:20
  Re: Well, about the incident at the westbound Niland distant signal.... Chris Walker 08-07-2023 - 15:19
  Re: BOB2, can you weigh in on this? Are you sure? No, but no short four percent segment is going ot bring a 125 train down to 40 mph. in a half a mile of 4% grade. BLOB222 08-07-2023 - 09:30
  Re: Did Nancy work for the RR before your mental illness and dope forced you to live in mom's basement and become a troll??Are you sure? No, but no short four percent segment is going ot bring a 125 train down to 40 mph. in a half a mile of 4% grade. BOB2 08-07-2023 - 12:19
  Bob2 can name call all he wants! He's still a moron BLOB222 08-09-2023 - 07:24
  Re: You must have scored some more dope Nancy.... BOB2 08-09-2023 - 18:08
  Re: You must have scored some more dope Nancy.... BOB420.69 08-09-2023 - 19:30
  Re: You must have scored some more dope Nancy.... Yep, I guess so... BOB2 08-09-2023 - 19:36
  Re: bob2 must have scored some more dope Nancy.... BLOB222 08-10-2023 - 17:25
  Re: bob2 must have scored some more dope Nancy.... BLOB222 08-10-2023 - 17:25
  Re: bob2 must have scored some more dope Nancy.... BLOB222 08-10-2023 - 17:25
  Re: Oh Nancy did this turn you on? BOB2 08-10-2023 - 18:26
  Re: Oh Nancy did this turn you on? BOB2 08-11-2023 - 11:22
  Re: Name calling is all you got! BLOB222 08-11-2023 - 13:03
  Re: BOB2, can you weigh in on this? Are you sure? No, but no short four percent segment is going ot bring a 125 train down to 40 mph. in a half a mile of 4% grade. Wacko Taco 08-07-2023 - 12:54
  Re: BOB2, can you weigh in on this? Are you sure? No, but no short four percent segment is going ot bring a 125 train down to 40 mph. in a half a mile of 4% grade. John Bruce 08-06-2023 - 14:49
  Re: BOB2, can you weigh in on this? Are you sure? No, but no short four percent segment is going ot bring a 125 train down to 40 mph. in a half a mile of 4% grade. FUD 08-06-2023 - 19:33


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