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From Amtrak's web site Train tracker this morning.
I thought the speed limit was 79?
- Thread starter me_little_me
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From Amtrak's web site Train tracker this morning.
There is a just a bit of wiggle room on the overspeed governer and 2 mph over doesn't trip it (although that might be about it). Also, I don't know if that reading is tied into the locos speedometer or whether it is calculating it based on GPS. The two may be the same (although likely GPS is the more accurate), but what the loco says is what the engineer is controlling.
crescent2
Conductor
I've seen the Crescent hit 80 (maybe 81?) according to my GPS, which surprised me (although it's barely over) because I have a friend who works for NS and I remembered him saying that engineers have ZERO leeway on speed restrictions. Varying a mph or two between gps and loco probably is within reason, though. (If reason matters!)
And what the engineer's job depends on.
Ziv
Conductor
Acela-like 150 mph would be great, but I would be nearly as happy just to see a SUBSTANTIAL portion of Amtrak's service being able to go 95 mph. 110 would be phenomenal!
I thought that PTC would have made a bigger difference, sooner. Obviously it is a complicated issue, but 79 mph is pretty darned pokey.
I thought that PTC would have made a bigger difference, sooner. Obviously it is a complicated issue, but 79 mph is pretty darned pokey.
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crescent2
Conductor
They can't do 79 in lots of places. 
Cole737
Train Attendant
My grandpa was an Engineer with the F40 on the Empire Corridor between BUF-NYP, and he said the limit was 79 with the overspeed set at 80 and a Never Exceed speed at 82. Maybe thats just the F40, but its probably something like that nowadays with the P42.
the_traveler
Engineer
The "limit" on most tracks is indeed 79 mph, but the speed governer does have a couple of mph leeway. Just like your car may go 57 in a 55 zone, but I doubt most times you will get a ticket. Likewise, the train may travel at 81 mph at times. But if the engineer goes 85 mph for 10 miles, the train would shut off if corrective action is not taken - plus the engineer will have some explaining to do.
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TVRM610
Conductor
It's very common to see speeds in the 80's from GPS in my experience. As others have said it could be the GPS is off, or it could be the speedometer on the loco is off by a couple of MPH... Meaning the engineer is seeing 79 but the "actual" real life speed is 81.
There's an old train video I had years ago that shows an Amtrak engineer on the NEC with a stopwatch counting the time between mileposts to check if his speedometer was right.
There's an old train video I had years ago that shows an Amtrak engineer on the NEC with a stopwatch counting the time between mileposts to check if his speedometer was right.
George Harris
Engineer
There are or were designated mileposts between which time was required to be checked on the watch for comparison with the milepost. Also the employee timetables have or had on them a list of speeds versus seconds per mile.
In years past the speed limits were much less strictly enforced. Now they are very strongly enforced. When you see a number above 79 on the GPS, the most likely answer is that the GPS is off. ZERO leeway is the norm today, and that is enforced with the feds looking over your shoulder.
In years past the speed limits were much less strictly enforced. Now they are very strongly enforced. When you see a number above 79 on the GPS, the most likely answer is that the GPS is off. ZERO leeway is the norm today, and that is enforced with the feds looking over your shoulder.
GPS can be wonky. I have an app that displays how fast I'm walking and how far I've walked. Then it runs a calculation to determine miles per hour, blah blah blah.
Anyway, there are times that app shows I'm walking 6-7 mph. Um, no. Not possible. Then, shortly thereafter, it will "catch up" and correct itself, showing an average closer to 3-4 mph, which is a normal/brisk walking speed, depending on one's ability.
Bottom line: The train is very likely going 79 mph, not 80 or 81.
Anyway, there are times that app shows I'm walking 6-7 mph. Um, no. Not possible. Then, shortly thereafter, it will "catch up" and correct itself, showing an average closer to 3-4 mph, which is a normal/brisk walking speed, depending on one's ability.
Bottom line: The train is very likely going 79 mph, not 80 or 81.
Silver Star rider
Service Attendant
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How does the train know how fast it is going? Rotations per minute of a axle ? How much metal can be worn out on a wheel to give a difference of a mile or two?
Yes, I have had GPS show slight movement when standing still. I have been told that when driving in a car, my speedometer shows 65, but the GPS says 61, go by the GPS.
Bruce-SSR
Yes, I have had GPS show slight movement when standing still. I have been told that when driving in a car, my speedometer shows 65, but the GPS says 61, go by the GPS.
Bruce-SSR
There are places on the SWC where the speed limit is 90 MPH.
MattW
Conductor
Car speedometers are usually set a few percent lower than actual speed to avoid lawsuits against the car companies for speeding tickets. I know on my car when the speedometer says 69, I'm actually doing right on the speed limit of 65 per the GPS.
In a previous discussion, I was of the impression that speed was deduced via radar Doppler shifting under the train using the ties or metal parts as reflectors... the comment then was that with wheel slippage, axle rate as not indicative.... but than again, could be misremembering.
There is a trackside detector along my Metrolink commute route that I've heard read out "eight zero" (or more) miles per hour which pretty much corresponds to what my GPS indicates. That stretch of track in Glendale California has a track speed of 79. I created a thread last year while on the Sunset Limited with a photo of my GPS indicating 81 and it was noted there that 1 or 2 MPH is not a big deal and not unusual.
I am on 98 right now and several times my GPS indicated that we were traveling at 81 mph.
Is that the GPS that makes you make wrong turns?? LOL
The really "good" GPSs make you turn onto RR tracks and right into an oncomng train! :giggle:
jis
Permanent Way Inspector
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Whether a wheel is slipping or not is determined by comparing the Doppler radar determined speed against the speed determined from angular velocity and radius of the wheel (roughly speaking).
I'm no scientist so I'll leave stuff like this to the experts of which this forum has many!
Isn't it amazing how in the old days railroads prided themselves on their OTP and engineers and conductors ran their trains with just employee timetables, pocket watches,basic signal systems, manual switches and written train orders??!!!
Isn't it amazing how in the old days railroads prided themselves on their OTP and engineers and conductors ran their trains with just employee timetables, pocket watches,basic signal systems, manual switches and written train orders??!!!
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Suspect CYAitis is directly proportional to litigation experienced (subject thereof) and sum of judgment/settlement payouts.
I have heard detectors transmit "eight zero mph" and "eight one mph" on occasion and to my knowledge nothing happened so there must be a little leeway, at least for momentary fluctuations.
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