Automatic equipment identification

Consisting of passive tags mounted on each side of rolling stock and active trackside readers, AEI uses RF technology to identify railroad equipment while en route.

In the late 1960s, railroads in North America began searching for a system that would allow them to automatically identify rail cars and other rolling stock.

Through the efforts of the Association of American Railroads (AAR), a number of companies developed automatic car identification (ACI) systems.

Based on the maritime companies' success with RF-based identification systems, Burlington Northern began a testing program in 1986.

In August 1988, the Burlington Northern Railroad presented a report on the results of their testing at the AAR Communication and Signal Annual Meeting.

Based on the spectacular results from both systems, the Burlington Northern asked the AAR to form a committee to write an AEI standard for the North American rail industry, and suggested that the AAR use the current draft ISO standard for container identification as a starting point.

The only major question still unresolved was whether to place tags on the sides of the rail cars or underneath, each approach having advantages and disadvantages in cost and maintainability.

With these recommendations, in August 1991, the O-T General Committee of the Association of American Railroads voted to make the AEI standard mandatory.

The AAR's S-918 specifications outline ten recommended frequencies ranging from 902.250 to 921.500 MHz, depending on the location of the reading device (in a yard or trackside), with a nominal transmitting power of 2.0 watts (measured at the transmitter).