The Philadelphia Chapter of the

National Railway Historical Society

Established in 1936

Conrail was doing some house cleaning, and look what they found in the back of the yard.

Conrail H39 coal hopper 435619 has its PRR heritage number on the upper right end panel just below its trust lettering, and just to the left are the yellow Wheel Inspection dot and its color coded ACI label. Here is a bit of history on both.

In the 1970's, AAR testing revealed that operational stresses on the steel of railroad wheels are greatest on the back face of the wheel rim, and that the common practice of stamping the back of the wheel rim contributed to the propagation of stress fractures and the resulting wheel failures. In 1978 AAR prohibited the manufacture of rim-stamped railroad wheels on new interchange freight cars. For cars already in service, the AAR required inspection of the wheels. A yellow dot denoted a car whose wheels had been inspected and either passed or were replaced. A white dot meant the rim-stamped wheels found would have to be replaced by the end of 1978 or the car would be prohibited from interchange service.

The Automatic Car Identification system, adopted by the AAR in 1967 and implemented by the railroads by the early 1970's, was an early attempt to allow the railroads to identify cars using a common standard. Unfortunately, it was optically based, and the accumulation of dirt, along with the normal wear and tear on the cars, often made the labels unreadable and led to the abandonment of the system by 1978.

All pictures September 1994 Copyright © 2006 John P. Almeida

Photographs for personal use only. All rights reserved by original owner of image. Reproduction or redistribution in any form without express written permission is prohibited.