Railroad Museum of Virginia

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Fri Nov 3 10:42:17 EST 2006


Gordon thanks for the history on the AI labels, it solves a mystery for me.
Cal Reynolds.
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From: <nw-mailing-list at nwhs.org>
To: "NW Mailing List" <nw-mailing-list at nwhs.org>
Sent: Wednesday, November 01, 2006 11:07 PM
Subject: Re: Railroad Museum of Virginia



> Viewing this caboose brought back memories to me. If one looks closely to

> the right of the "NW" one can see a painted-over ACI (Automatic Car

> Identification) label. Many of you can remember seeing these colored

> labels on both sides of equipment in years gone by, or in old photos from

> that era. In this Sylvania developed system, each stripe was coded in red,

> blue and/or white.

>

> Reading up from the bottom, the first stripe was a "start" stripe, and the

> next four stripes represented the reporting marks (0550 as assigned by the

> AAR for the N & W as best I remember), the next six stripes represented

> the equipment number (518666 in this case) and the penultimate stripe was

> a check digit that was a mathematical derivation of all of the other

> numbers. The last stripe at the top was a "stop" stripe.

>

> The stripes were retroreflective, meaning that they reflected a light from

> a scanner straight back into the scanner. Each wayside scanner used a

> fast vertically rotating (1750 rpm as best I remember) wheel with

> multi-faceted mirrors on its periphery that reflected a internally

> generated beam of light to scan the label from bottom to top several times

> even at high train speeds past the scanner. The light was reflected back

> into the scanner where sensors detected the red, blue or white codes and

> converted these into the reporting marks and equipment number. This

> information could be used by a railroad to determine the identification of

> each piece of equipment in a train.

>

> Although initial tests verified the technical proficiency of the system

> before it was mandated by the AAR, after about 1-1/4 million cars had been

> equipped, experience revealed that the read rate in service was less than

> expected because of dirt buildup on the labels as well as occasional label

> damage.

>

> I served on an AAR Technical Task Force to see what could be done to

> improve this optical system. We considered several possible solutions

> without sufficient success.

>

> The AAR then formed a Task Force for New Concepts in ACI. I served on

> this committee also, and we considered all known systems for equipment

> identification, finally narrowing the search to a system using microwave

> scanners to interrogate passive responders on the equipment. This is the

> system that was subsequently adopted by the AAR, and is currently in use,

> having replaced the optical system after tens of millions of dollars had

> been spent on the latter.

>

> A little bit of history for those who have wondered about these colorful

> labels.

>

> Gordon Hamilton

>

>

> ----- Original Message -----

> From: <nw-mailing-list at nwhs.org>

> To: <nw-mailing-list at nwhs.org>

> Sent: Wednesday, November 01, 2006 9:48 PM

> Subject: Re: Railroad Museum of Virginia

>

>

>> Picture attached: Norfolk & Western C31P caboose 518666 in

>> downtown Portsmouth, VA.

>>

>> Jerry Kay, Portsmouth

>>

>>

>

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