# Car Counter on detector

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#### N9JIG

##### Sheriff
Moderator
I can hear at least one of the Arizona and California hotbox detectors from home and it has the expected items like temperature, speed and axle count. It also announces the car count.

How is it getting this car count? Is it using the AEI tag? Dividing the axle count by 4?

#### reconrider8

##### Member
Feed Provider
You have to figure in the locomotive also some are 4 some are 6 axles

#### AK9R

Super Moderator
It's hard for me to imagine that a defect detector has the intelligence to detect AEI tags and count them. But, railroad technology marches on. Is it possible that the DD is picking up on gaps between cars?

Dividing axle count by 4 really goes out the window when you have a multiple-well double-stack car that consists of 4 cars and 5 trucks or an articulated auto rack with 2 cars and 3 trucks.

#### franks_ham

##### Member
From a professional's view...

The axles are counted, and spit out on the reading. The conductor verifies on the paperwork that's how many axles they should have and if it matches we keep rolling. If it's off, even by ONE axle, notify the dispatcher and take proper measures.

For the non-railroader, count the engines on the train, pay attention to if it's a 3 axle (road power) or 2 axle (yard/local power) and add those axles up. Then subtract them from the final axle count and divide that by 4, you'll get how many cars are on that train! For trains with "double-stack cars", figure 10 axles per 5 car set, so you do the same math.

164 axles readout: You saw 4 engines, subtract 24 axles, that's 140 axles for the train itself. on a "double-stack train" that would be 14 sets of stacks. On a normal train, that would be 35 cars.

Get the idea? Enjoy the newfound knowledge!

Regards,

-Frank C.

#### wa8pyr

##### Technischer Guru
Moderator
From a professional's view...

The axles are counted, and spit out on the reading. The conductor verifies on the paperwork that's how many axles they should have and if it matches we keep rolling. If it's off, even by ONE axle, notify the dispatcher and take proper measures.

For the non-railroader, count the engines on the train, pay attention to if it's a 3 axle (road power) or 2 axle (yard/local power) and add those axles up. Then subtract them from the final axle count and divide that by 4, you'll get how many cars are on that train! For trains with "double-stack cars", figure 10 axles per 5 car set, so you do the same math.

164 axles readout: You saw 4 engines, subtract 24 axles, that's 140 axles for the train itself. on a "double-stack train" that would be 14 sets of stacks. On a normal train, that would be 35 cars.

Get the idea? Enjoy the newfound knowledge!
If Peter left Chicago on a train going 90mph, and Paul left NYC on a train going 80mph, how many apples will they have when they meet at Cleveland?

Do math in our heads trackside? Takes all the fun out of it, I'd rather just sit there, watch and take pictures!

#### N9JIG

##### Sheriff
Moderator
I get all that but what I am trying to figure out is how the DETECTOR knows there are xx cars.

Other than AEI tags how can it differentiate between 4 and 6 axle locomotives, the multi-element container cars and the occasional 6-axle special service car?

I would think some sort of gap counter would work but that could be affected by the aforementioned multi-element container cars and the occasional semi-permanently coupled auto rack.

Perhaps close is good enough here?

#### wa8pyr

##### Technischer Guru
Moderator
I get all that but what I am trying to figure out is how the DETECTOR knows there are xx cars.

Other than AEI tags how can it differentiate between 4 and 6 axle locomotives, the multi-element container cars and the occasional 6-axle special service car?

I would think some sort of gap counter would work but that could be affected by the aforementioned multi-element container cars and the occasional semi-permanently coupled auto rack.

Perhaps close is good enough here?
My guess would be that they're probably using an AEI reader to get a count; if the train has 3 engines and 47 cars, and the DD says "50 cars" then all is well.

Seems like adding a simple AEI reader to a DD wouldn't strain the budget too much; after all, there are guys out there now using RFID readers and Raspberry Pi computers to whip together their own AEI readers at relatively low cost, so it couldn't cost the railroad too terribly much to add one to the DD.

#### AK9R

Super Moderator
...after all, there are guys out there now using RFID readers and Raspberry Pi computers to whip together their own AEI readers at relatively low cost...
And, deploying them on private property along rail lines to provide information to shipping customers that the railroads wouldn't provide. I believe that some of the guys deploying these rogue readers were caught and had fines levied against them.

#### N9JIG

##### Sheriff
Moderator
OK, I just heard that detector again (AZCA MP 48.4). It reported 96 axles and 23 cars. Now 23x4=92, meaning that there is an extra 4 axles, likely for the locomotive.

This leads me to believe they are using AEI for this and that the AEI reader differentiates between locomotives and cars. Or else it could be that there are a couple 6-axle cars...

#### wa8pyr

##### Technischer Guru
Moderator
OK, I just heard that detector again (AZCA MP 48.4). It reported 96 axles and 23 cars. Now 23x4=92, meaning that there is an extra 4 axles, likely for the locomotive.

This leads me to believe they are using AEI for this and that the AEI reader differentiates between locomotives and cars. Or else it could be that there are a couple 6-axle cars...
I have seen an AEI reader in close proximity to a defect detector somewhere (wish I could remember where), so I have a sneaky suspicion that's what's going on. A related question would be "is the DD calling the AEI data back to the mothership?"

##### Member
Used to work in the trade - we called them double articulated well cars - seems like all were TTX.

I ge
Other than AEI tags how can it differentiate between 4 and 6 axle locomotives, the multi-element container cars and the occasional 6-axle special service car?

Perhaps close is good enough here?

##### Dual Citizen Member
How is it getting this car count? Is it using the AEI tag?
Yes, AEI tag reader. The office in Parker also automatically gets the AEI data, detector data, and a recording of the Rice (48.4) detector message. ParkSierra Rail Group was always big on playing with technology.

#### N9JIG

##### Sheriff
Moderator
Yes, AEI tag reader. The office in Parker also automatically gets the AEI data, detector data, and a recording of the Rice (48.4) detector message. ParkSierra Rail Group was always big on playing with technology.
Thanks,that certainly makes sense!

#### franks_ham

##### Member
I get all that but what I am trying to figure out is how the DETECTOR knows there are xx cars.

Other than AEI tags how can it differentiate between 4 and 6 axle locomotives, the multi-element container cars and the occasional 6-axle special service car?

I would think some sort of gap counter would work but that could be affected by the aforementioned multi-element container cars and the occasional semi-permanently coupled auto rack.

Perhaps close is good enough here?
I guess it's a SP now UP thing, but I've NEVER heard a detector call out car counts, just (No)Defect, total axles, train speed and ambient temp...

Regards,

-Frank C.

#### N9JIG

##### Sheriff
Moderator
I guess it's a SP now UP thing, but I've NEVER heard a detector call out car counts, just (No)Defect, total axles, train speed and ambient temp...

Regards,

-Frank C.
It was determined that this is an AEI-equipped detector set up by the Arizona and California Rwy near Rice, CA. It can be heard for great distances due to the repeater on Smith Peak, that is why I am hearing it halfway between Wickenburg and Phoenix.

This is also the first time I have heard car counts on any railroad.

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