Diamonds are for girls, but trouble for me

"There's something happening here / What it is ain't exactly clear" --Buffalo Springfield.

Good Morning to All

I live in Chicago where I use the Grayland station (Milwaukee Ave. & Kilbourn) on the Metra
Milwaukee District line to visit the northwest suburbs. Around 8:30am on weekdays a Milwaukee-
bound Amtrak - The Hiawatha - comes through at fast speed. After it passes I can hear the
"clackety-clack" as the cars pass over, first, a single diamond at a defunct spur, then a
triple diamond where it crosses the Union Pacific (UP) northwest line.

I am interested to know the train's speed, so on the morning of September 3, I turned on my phone's
sound recorder to register the event. On playback I noted that, from the time the rear railcar
passed me at Grayland, to the time I could hear the same car pass over the triple UP diamond, 21
seconds had past. Later that day I measured the distance, using Google Earth, from Grayland Sta.
to the UP diamond as approximately one mile (see attachment).

Taking into account that sound requires about five seconds to travel one mile, the real elapsed
time for the train to journey from Grayland to the UP diamond would be only 16 seconds. Now if the
train is travelling one mile in 16 seconds, then I calculate it is traveling at 3.75 miles per
minute (60 sec. / 16 sec.), which converts to 225 mph! ((60 sec. / 16 sec.) * 60 min.) What am I
doing wrong?

I believe the distance measurement on Google Earth to be correct simply by comparing it to the
lengths of the adjacent Chicago city blocks - eight long blocks to the mile. I tested the recorder
against music from the radio. It played back at the same pitch and tempo as the radio, so I
believe the recorder is working correctly. There are no other diamonds or switches on this stretch
of track.

On Sept. 30 I made a second recording with practically the same results (see the summaries below).

One more puzzling item to complete the story. You will note from the recording summaries below
that the sound from the defunct diamond occurs at exactly one half the time as the sound from the
UP diamond. But the defunct diamond is only 0.32 miles from Grayland, where the UP diamond is 1.00
mile away.

Doing the math to determine the speed, 0.32 * 5 seconds = 1.6 seconds for sound travel. So 10.5
seconds (average of two recordings) - 1.6 = 8.9 sec. for train to journey the 0.32 miles. So it
travels one mile in 28 seconds or 2.14 miles per minute which converts to 128 mph. Better, but
still unacceptable. Why the discrepancy in sound travel? I don't know.

Does anybody here live in the Chicago area? Assuming I haven't made a computation error, it would
be helpful if someone could go out and validate my recordings. Repeat measurement would be a good
and necessary first step in an investigation.

Thank you all.

Keen


SUMMARIES OF THE TWO RECORDINGS*
Phone audio file made Sept. 3
min. : sec.
00:00 recording begins
00:44 last car passes Grayland Sta.
00:55 last car passes over a single diamond intersection of a defunct line just south of Irving
Park Rd. (see attached aerial image)
01:05 last car passes over the UP triple diamond.

Phone audio file made Sept. 30
00:00 recording begins
00:39 last car passes Grayland Sta.
00:49 last car passes over a single diamond intersection of a defunct line just south of Irving
Park Rd. (see attached aerial image)
00:59 last car passes over the UP triple diamond.

*These recordings are available to you.

No Amtrak is traveling 225 MPH - ANYWHERE!

It takes 1 minute to travel a mile at 60 mph (so about 4 minutes at 15 mph). I think that's a place to start with your math.

There are apps which use your phone/tablets camera to measure speed, which might be easier.

Inspired by SwingMan's post above, let me state this a different way. I estimate the actual speed of the Amtrak at 60-70 mph as it passes me at Grayland - let's say it's going 60. So it should take 65 seconds for (sound of) the last car to go from Grayland to the UP triple diamond...60 seconds for actual travel at a mile a minute, plus five seconds for the sound to reach me from the diamond.

Then why is it only taking 21 seconds (20 seconds on the second recording of 9/30)??!! In that respect why is the sound even reaching me at all if the diamond is a mile distant (and that assertion has not yet been challenged). Seems to me a mile would be enough distance to squelch most sounds.

Thoughts?

I would just get a stopwatch (most phone have one pre downloaded but I’m sure there is other ones you can download) and time it from the end of the platform till the diamond visually and go from there.

Maybe those sounds you hear are coming from elsewhere than the spots you think they are coming from?

I'm not familiar with the area, did not hear your recordings, nor did I verify distances - but here are my thoughts and analysis:

When doing time and distance evals, you should convert everything to feet per second (or if metric, meters per second).

Ignoring the data you collected, first assume the numbers that would be a normal condition; which even though I do not know the operations in that area, I will assume the train is moving consistently at 75 MPH.

75 MPH is about 110 feet per second.

To travel a mile, or 5280 feet, at that speed, it would take the train about 48 seconds. Right there should send up a red flag that the second sound you here is not a mile away, assuming your measurements are close within what you reported. Continuing with the assumption:

Speed of sound varies as it's speed can be affected by humidity, air temp, etc, but an average speed of 1130 feet per second is commonly used. Using this number:

Sound from 1 mile should take 4.7 seconds. So at 75 MPH, the sounds on the recoding for traveling a mile should be around 52 seconds. Since the time you have is 20 seconds, this should confirm that the second sound is not a mile away. Moving on:

Using your first point, the abandoned diamond which is .32 miles, or 1690 feet, it would take the train about 15 seconds to travel that distance if moving 110 feet per second (The assumed 75 MPH).

With this info, I would be confident that the sound you believe is the last car passing over the triple diamond is actually the sound of the last car passing over the abandoned diamond. The first sound could be caused by a joint or a defect in the rail. Again, this is assuming the distances you gave for each diamond are close to correct.

Assuming that the last sound is the first diamond at .32 miles, or 1690 feet, it takes sound 1.5 seconds to travel 1690 feet, and if the time you recorded is 20 seconds, the train traveled between those two points in 18.5 seconds; which is about 91 feet per second; when converted to miles per hour = a more reasonable 62 MPH.

To confirm: traveling at 91 feet per second and using the 10 seconds between passing you and the first sound, the distance to the area generating the sound should be around 800-850 feet away or about half way between the first diamond and Grayland Station. Go to the location of the abandoned diamond and as a train approaches, see if you can hear any chatter between you and the station. I would be interested to know the outcome.

Roadmaster - I had already considered the possibility that the first diamond is actually the second sound. I rejected that because 1) the track is without a switch or diamond from Grayland to the first diamond; 2) I know how the sound of the second (triple) diamond differs from the first (single) because I have been over both many times in Metra trains. The second sound just sounds right for the second diamond.

However - the numbers work in your scenario, and there is no sound coming from the second diamond which is as it should be, being a mile distant. This deserves a trackside investigation, and I will do this. I just have to find away to keep from being arrested for trespassing on RR property (as has happened to me once). There are usually work crews along the way, so I have to find a hole in the fence, evade the men in orange, look for a track defect somewhere from Gray to diamond 1, examine the diamond in real time, and wave at all the passing inbound Metra trains.

I hope I can corroborate this for you. If not, you'll hear from me again!

Keen

Welcome to the forum! Don't forget there is a fantasic hobby shop called "Grayland Station" but it's up at Devon station. Steve is a really nice guy with all kinds of train stuff.

I have a better idea. Tomorrow a.m., if it's not raining, I will stand on the platform and take two pictures of the train at the point when I hear the first and second noises. If the train's rear end is visible at the second noise (what I think/thought to be diamond 2) then Roadmaster's scenario is correct. If it's not visible - you cannot see any detail of the front or back end of a train that is a mile away - then we're back to square one.

If tomorrow it rains I'll make a rain date.

K

I just looked at the area via google maps. There is nothing physical I can see that would collaborate my theory except for maybe a jointed rail connection. Also, there is no need to trespass at all let alone for something as trivial like this. There looks to be plenty of public areas near the tracks that you can hear what is going on with no visual confirmation needed.

Here’s a cheaper solution, that doesn’t involve trespassing. Ride the train with a stopwatch in hand. You will be able to determine the exact time to click the stopwatch. You’ll also be able to determine if there is a track defect between the station and your first diamond. You will be able to calculate the exact speed. Good Luck!

There is no need or call for trespassing; That is never an acceptable option in pursuit of a 'railfan' hobby. I know you said you weren't interested in a 'speed' app, but both it and the stopwatch will both tell you the speed of the train (without riding, even); Simply time how long the train (engine pilot to last car end) takes to pass an exact spot on the platform (train travels x feet in y seconds).

Or, for an even cheaper solution, just use Amtrak's Track a Train map...

No need to go out with a stopwatch when you can track the train online and see its speed right there.