Don B Wrote:
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> Did the ditchlights replace the gyralite because
> the high upkeep?

Dr. Zarkoff is correct. There is no simple answer to your question.

The decision on whether to remove oscillating signal lights (whether Mars or Gyralite) was up to the management of each individual railroad that used them.

On some railroads, oscillating signal lights were replaced with non-oscillating signal lights. For example, SP initially began using Power Parts Osciltrol lights in place of Gyralites, then abandoned those in favor of Prime solid-state sequential beacons before discontinuing the use of signal lights altogether.

Ditch lights (actually called "Auxiliary Lights") became a federal requirement after Title 49 CFR 229.125 became law. Here is a link to the law, which explains everything about them.

[www.versuslaw.com]