What year did ditch lights become mandatory?

I modeling an era in the not-too-distant past (1990-2000). If there’s any way possible, I’d like to not have to install ditch lights on every single one of my loco’s to make them appear prototypically correct. Was it sometime after 1990 — or before then — that the Gov’t required all engines to use ditch lights?

TIA…

http://www.trainweb.org/gyra/gyra_use.htm

I found this on it. Hope it helps.

Excellent, I went to the “Ditch-Crossing Lights” link and it told me exactly what I needed to know!

Thanx Loathar, I owe ya one…

RAILROAD LOCOMOTIVE SAFETY STANDARDS

Subpart C–Safety Requirements, Sec. 229.125 Headlights and auxiliary lights

Effective December 31, 1997

All locos were required by the FRA to have the triangular light pattern (auxiliary/ditch lights) by that date: Dec. 31, 1997

Happy Railroading! [:)]

OK. My railroad is now set in 1996, before the mega mergers (BNSF, Conrail split) and before ditch lights! I like them, but they sound hard to add.