https://www.railwayage.com/mechanical/locomotives/tier-4-all-notches-all-the-time/ EMD was ‚forced‘ to discontinue its legendary 2-stroke diesel prime mover series (567/645/710) because EMD couldn’t‘ find a way to make it meet EPA Tier 4 emissions standards. But apparently there is a way, with potential consequences for the industry for years down the road.
