Mook,

I sat on a technical committee that awarded a lot of funding for air pollution control technologies, that "exceeded" adopted regulations including a lot of work on Tier 3 and Tier 4 heavy duty engines (construction equipment, school buses, transit buses, trash trucks, and even monies for locomotive engine development. And, yes, we do have a good range of cost effective and compliant Tier 4 technologies for most applications, except for locomotives. The most cost effective Tier 4 fix is to convert to ,CNG (less costly and easier to achieve) but this is very difficult for locomotives. Cleaner diesel will help, but will be very costly, and reduces the cost effectiveness (usually based on cost per ton of emissions reduced)of diesel based solutions. So I have no problem with the ideal of technology "forcing" regulations, like this standard, per se.

In my opinion, the Tier 4 requirement for locomotives, at this time, is an example of the perfect being the enemy of the good. It is premature. From Tier One to Tier 2 was very easy, and Tier 3 compliant technologies were being demonstrated in the late 90's, so by the time of the Tier 3 regulations ten years later in '08, there was ample and well proven product available which would meet the requirement. This is simply not the case with Tier 4 for locomotives.

So yes, there will be a tendency to reduce orders due to uncertainty, and yes there will be a push to maintain and rebuild much dirtier locomotives still in service, since a supply of reliable Tier 3 replacements will not be available. So the result is uncertainty, higher costs, and more dirty air to breath, than would have otherwise been the case, if RR's were allowed to continue to buy Tier 3 engines.

Which I guess could be a "win-win" in some weird worlds, maybe just not this one?