In 1977, I timed a mile on the Washington section of a very late National Limited at 30 seconds. Granted, unscientific, but closer to 120. I wrote about it in "One fast GG1 on a roll," in TRAINS in the early 2000s. In short, our very late Washington section of the National Limited came off the Port Road branch and got onto the Corridor. We started moving, and i mean moving. You could feel the GG1 tugging the 2 coaches faster and faster. Ballast was banging off the underneath . I held my Boy Scout watch up to the dirty window and began timing mileposts. We quickly were up to 45 seconds between them. We went even faster, and I caught several mileposts at 30 seconds between them. We were flying. We stopped for exactly 7 seconds in Baltimore, then sped out of the station. Folks hadn't even got up to get off yet. They were angry, and got put off at the Beltway station. Ah, the good old purple and orange Amtrak years.
One question I have: When using a stopwatch to time mileposts for some of these speed claims, was it an actual mile? Many curve reductions or out and out line relocations resulted in mile posts not being a mile apart any more. The 160ish mph claims would make sense if they happened to use a "short mile" to time speed. (I'm not specifically questioning you, Cresentlover, since you did it over multiple miles)
rrnut282One question I have: When using a stopwatch to time mileposts for some of these speed claims, was it an actual mile? Many curve reductions or out and out line relocations resulted in mile posts not being a mile apart any more. The 160ish mph claims would make sense if they happened to use a "short mile" to time speed. (I'm not specifically questioning you, Cresentlover, since you did it over multiple miles)
I carry a stop watch in my truck. Periodically I will use it to time Mile Posts on the Interstate. For the most part, they measure nearly identical distances which I have to believe are one mile increments - HOWEVER, the stop watch will indicate mislocated Mile Posts - one mile shorter and the next mile longer, however the two mile cumulation is right on.
On the railroad, I can easily see a derailment wiping out a Mile Post and after the clean up is complete and the Mile Post gets replaced, but outside of its correct position.
Never too old to have a happy childhood!
I have had several conversations with a railfan in Europe who privately gave me some advice on the methodology of timing with a chronograph; I have permission from him to repost what he said and will do so when I have better access to a proper computer...
We have had a number of discussions on 'short' and 'long' miles and the reasons therefor over the years. Yes, you time multiple miles to ensure reasonable 'average' if any one mile happens to be nonstandard.
If I want to do some timing, I use my digital stopwatch: very accurate, readouts to 1/100 second, large buttons, and cheaper.
Accuracy will be limited by how consistently the start/stop buttons are pushed with respect to the the passing of the mileposts.
An article written Ca 1880 on the "Electric Time Service" had a few paragraphs on the transit telescope used for establishing the current time using the Right Ascension of the star being observed. The observer would press a key when the star crossed the transit line and note was made that there was several hundredths of a second variation in the reaction times of the observers.
Overmodif any one mile happens to be nonstandard.
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Erik: I think a person's slowness in starting and stopping the timer would even out beginning and end. It's good enough for this purpose. Hand-held stopwatches were used for years in track and swimming adequately.
charlie hebdo Erik: I think a person's slowness in starting and stopping the timer would even out beginning and end.
Erik: I think a person's slowness in starting and stopping the timer would even out beginning and end.
That's why I wrote "consistently". A flip side of the "Electric Time Service" example on timing is that to do as well as a major league pitcher, the ball has to be released within a +/- 5 millisecond time window. With 10 millisecond time steps, the source of error is more likely the operator than the watch.
In regards to measuring a train speed by timing the mileposts, 120 MPH is 30.000 seconds between mileposts, 121 MPH is 29.752 seconds, and 115 is 31.304 seconds, so I would figure someone with stopwatch experience could tell between 120 and 121 MPH.
Unless you know the actual mile lengths, don't bother with the stopwatch. Anyone who wants to document his claim needs to give a nice long sequence of passing times at a series of mileposts (or stations), and watch times to the second are good as any for that. And name the mileposts -- passed milepost 54 at 4:11:31, passed milepost 53 at 4:12:01, passed milepost 52 at 4:12:31...
If the claim is far-fetched, then the sequence needs to be long, to hope to be convincing.
Americans don't do that sort of thing, so American feats have never been documented.
Erik_MagThat's why I wrote "consistently".
His point is a valid one in all examples so far given. Reaction time is deleterious in things like brake application, timing of star crossing, or monitoring of ball release. As he pointed out, most of the psychophysical factors 'cancel' when the measurement involves sequential starting and stopping ... as timing mileposts does.
It is important to keep as many perturbing factors, such as 'excitement' or any attempt to guess when to hit the button 'early' to make the click coincide directly with the reference 'moment', minimized to achieve the best haptic consistency. Strange as that might seem.
BigJim Overmod if any one mile happens to be nonstandard. Well, for the nit-pickers, that is almost all of them to some extent.
Overmod if any one mile happens to be nonstandard.
Well, for the nit-pickers, that is almost all of them to some extent.
Depends where you are... sometimes track charts have the distance between mileposts on them.
Generally, mileposts were often placed without great precision. Then, over the years as alignments were improved, some miles became miles in name only, often shortened by a thousand feet or more. Sometimes the RR would go back and reset all the mile posts to 5280. So, if you want to get an idea of how fast you're going, mileposts will work, but you need to do a bunch in succession to have an real idea.
With just a few cars, a GG1 could have a balance speed on the level north of 120 mph, assuming it could put 4600 HP to the rail a that speed.
I used to ride between Phila and NYP a bit in the 70s and would time miles. They usually seemed to operate around 90 mph even though track speed was only 80 mph for locomotive hauled trains at that time.
-Don (Random stuff, mostly about trains - what else? http://blerfblog.blogspot.com/)
Randomly selected 5 miles on Chicago Line - ft between:
5193
5367
5280
5380
Quickly scanning a few pages, it appears that about 80% are 5280 and the rest different.
Overmod Erik_Mag That's why I wrote "consistently". His point is a valid one in all examples so far given. Reaction time is deleterious in things like brake application, timing of star crossing, or monitoring of ball release. As he pointed out, most of the psychophysical factors 'cancel' when the measurement involves sequential starting and stopping ... as timing mileposts does.
Erik_Mag That's why I wrote "consistently".
My point in using "consistently" was in respect that variations in pushing the start/stop button can be substantially less than the reaction time (in my line of work reaction time = propagation delay and variations in timing = jitter). Another way to put it is that the 1/100th second resolution of the digital stopwatch should be fine for 99+% of the users and finer resolution would be needed by only a few very skilled users. One advantage of the digital stopwatch is that it is easier to read than an mechanical stopwatch.
The "up to date" approach for measuring speed would be using a GPS receiver, though getting adequate reception inside a RR passenger car may be problematic.
oltmannd Randomly selected 5 miles on Chicago Line - ft between: 5193 5367 5280 5280 5380 Quickly scanning a few pages, it appears that about 80% are 5280 and the rest different.
Now, go factor in the time it takes to start/stop a stopwatch or just look at your watch and what do you get? Something so insigficant that only the nit-pickers give a fat rat's petoot about!
Erik_MagMy point in using "consistently" was in respect that variations in pushing the start/stop button can be substantially less than the reaction time (in my line of work reaction time = propagation delay and variations in timing = jitter).
As it happens, I had the chance to play around with this in Professor Galanter's lab. The specific issue is the uncertainty in latency between two haptically-similar events (here, using the thumb to press the stopwatch button while observing a 'zero crossing' timing event, whether it is to start or stop the device). Most RT studies seem to concentrate on more complex actions, notably the combination of perception and reflex arcs involved in foot-braking an automobile. The specific data for stopwatch manipulation involves far shorter nerve paths, and with training (as my European correspondent pointed out) quite a bit of the latency variation corresponding to jitter could be avoided. But it is still present.
There is better portable instrumentation available today, which is capable of reading neuromuscular actuation directly (to the necessary precision) and associate that with absolute event timing from a more precise source (e.g., optical sensing using edge detection, for this example of timing mileposts). For an investment of about $300 plus a suitable smartphone (which can be obsolescent; you only need 'communications' if you have no other way to download software) you could conduct proper data gathering and perform reasonable analysis on the results for this very specific application. The results would be useful research in a number of significant respects involving accuracy of handheld timing -- if it wouldn't already tell you what Big Jim already knows: the variance is already on the order of the precision needed for measurement.
Using some of his examples, if the variance is on the order of the 0.1sec commonly quoted in what there is of the literature, even his longest 'mile' (which is out 54 feet) produces a difference at 100mph that is only about three times the variance. Something pointedly not mentioned is whether the distribution is symmetric - does a given individual routinely tend more toward anticipatory variance, or lag? Again you could produce a correction table, if you are of nitpicking persuasion ... and this might actually be 'important' in critical cases, for example if you absolutely need to know as a railfan that your train went 100mph instead of 97.94.
Another way to put it is that the 1/100th second resolution of the digital stopwatch should be fine for 99+% of the users and finer resolution would be needed by only a few very skilled users.
I might point out that for 100mph timing, a 1/100 minute stopwatch gives you nominal precision to a mile per hour. The 1/100sec resolution is fine ... until you start invoking that number of decimal places in the precision of the measurement. Lest you think this is trivial, the "126.1mph" claim for Mallard relies upon a very short trace at the indicated speed, which brings up the timing precision of the motor driving the chart recorder, probably demonstrably well short of 1/100sec accuracy and perhaps whatever the corresponding measure to wow/flutter would be for charts. Again, agreeing with Big Jim, it's hopelessly nitpicky to derive meaning from this kind of record ... but don't try telling that to a wide cross-section of English railfans!
One advantage of the digital stopwatch is that it is easier to read than an mechanical stopwatch.
That is true even if you have a true 3sec/10ms stopwatch (which is a joy to behold if you like fine machinery) but a much more important difference is the longer muscular 'throw' and effort, and internal mechanical factors, involved in starting or stopping a mechanical watch. Somewhere I have data about the difference in haptic touch for various kinds of typewriter-keyboard feedback ... and the much larger difference, including key-to-key variance, an important potential input for biometric security, for mechanical typing.
The big problem I have with digital stopwatches is the deceptive precision they give. I happily wear a watch that, among its other features, provides a 1/1000 timing function (and the quartz chip in the watch supposedly has an oven to permit that precision, although to date I haven't checked this scientifically!). The slop in the mechanical pusher switches alone is a substantial multiple of .001sec, and there is of course no breakover or other haptic confirmation when the button is 'making' for the timing command. (My somewhat unscientific testing indicated somewhere around .044sec variance when quickly starting and stopping by pure reflex) While there are contacts for more direct electrical actuation, I have to conclude that at least that last digit will vary so much that it can't be relied on for something meaningful. But tell that to the average guy who bought one of these watches for three-digit-precision bragging rights!
Erik_MagThe "up to date" approach for measuring speed would be using a GPS receiver, though getting adequate reception inside a RR passenger car may be problematic.
I do it all the time using app on phone. Works just fine nearly all the time. There was one time I had zero luck, but my guess is that they had gold film on windows... Can't remember exactly where this was...maybe Norway.
On HST in England: https://photos.app.goo.gl/8mXfg1yVsQVXhFWM9
In Viewliner: https://lh5.ggpht.com/-K9mavYB4nZA/VA8JhbzwXaI/AAAAAAAAj0A/uB-CD0OEi_g/s1600/Screenshot_2014-09-09-10-05-27.jpg
In Sweden: https://photos.app.goo.gl/WwnNUeYx39FV2Tp88
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