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Federal Register / Vol. 62, No. 28 / Tuesday, February 11, 1997 / Proposed Rules6373the proposed Tier II standards, but mayrequire a somewhat different technologymix. An analysis of the cost andtechnology implications of this optionare contained in the public docket. EPArequests comment on all aspects of thisoption, including its technology andcost implications. EPA also requestscomment on the cost and technologyimplications of requiring additionalNO X reductions, including theimplications for control of PM. Finally,EPA requests comment on whether itshould consider more stringent Tier IIPM standards than those proposed, andwhat the implications of such standardsmight be for NO X control, as well astheir cost and technology implications.Should the Agency considertightening the particulate standards forTier 0 and Tier I locomotives to ensurethat particulate emissions do not exceedthe current baseline level (0.34 g/bhp-hrfor line-haul locomotives); and wouldmore stringent particulate standardsrequire relaxation of the NO X standards?For example, EPA could set theparticulate standard for Tier 0locomotives at 0.40 g/bhp-hr toeffectively prevent any Tier 0locomotives from emitting above thecurrent baseline; and set the particulatestandard for Tier I locomotives at 0.3 g/bhp-hr to achieve a 25 percent reductionin emissions from the current baselinelevel. If the Agency were to adopt morestringent particulate standards for Tier 0locomotives should they be phased-in toprovide more leadtime toremanufacturers? The Agency requestscomment on whether it should considergiving some form of credit forlocomotives that are designed to shutdown at idle, given that suchlocomotives would not be generatingidle emissions in use, but would haveidle emissions measured duringemissions testing. Finally, the Agencyrequests comment on the stringency andform of the smoke standards.Auxiliary engines used only toprovide hotel power for the passengercars of a train are currently subject tothe applicable emissions standardspreviously adopted for nonroadcompression ignition (CI) engines over37 kW 11 . These standards, shown inTable V–6, will apply regardless ofwhich of the duty-cycle optionsdiscussed is adopted.In addition to proposing separateemissions standards for the threecategories of locomotives based on dateof original manufacture, the Agencyconsidered three options for separateemissions standards for each of the11 59 FR 31335, June 17, 1994, and 40 CFR part89.three distinct types of locomotiveoperation described above (switch,passenger and line-haul). Of the threeoptions considered, EPA is proposingthe ‘‘dual-cycle’’ option, where alllocomotives, regardless of theirintended usage, would be required tomeet both switch and line-haul dutycyclestandards. Details of this option,as well as the other two duty-cyclebased options EPA considered (i.e., the‘‘class-specific’’ and the ‘‘single-cycle’’options) are discussed in the followingparagraphs.The standards being proposed aredesigned to achieve very significantreductions in NO X emissions from thebeginning of the program, whilesignificant reductions in the emissionsof other pollutants would only beachieved under the Tier II standards,effective in 2005. This is because NO Xis the only pollutant for whichlocomotive emissions contribute morethan one percent of the estimatednational inventories (see Table IV–2).EPA believes that the Tier 0 and Tier Iemission standards for NO X might notbe achievable if significant reductions inHC, CO, and PM were also required.Thus, the standards being proposed areintended to achieve the greatestenvironmental benefits as early aspossible.Class-Specific OptionGiven the three distinct types oflocomotive operation discussed above(i.e., switch, passenger and line-haul),the first option the Agency consideredwas separate emission standards andduty-cycle weightings for each type (i.e.,the class specific option). Separate dutycyclestandards were intended toaddress the wide disparity in usagepatterns for the different groups, and theeffect of such use on emissions.Although duty-cycles were developedfor average locomotive operation, widevariations in actual operations do occurwithin the three basic types of operation(i.e., switch, passenger and line-haul).To prevent substantial disparitybetween the in-use emissions rate andthe emissions rate during the test cycle,EPA considered notch-by-notchemissions standards for all notches (i.e.,notch caps) for all pollutants. It shouldbe noted that if a locomotive wereoperating at the levels of the notch capsfor all notches, its duty-cycle-weightedemissions would be much higher thanthe duty-cycle standards. Thus, theproposed duty-cycle standards wouldprevent any locomotive from emitting atlevels of the notch caps for all (or evenmost) notches. These notch-by-notchvalues were chosen to allowmanufacturers and remanufacturerssome degree of flexibility in meeting theduty-cycle standards, while at the sametime insuring that differences in theutilization of locomotives whichnormally occur will not causesignificant divergence from the dutycycleemission standard. To provideadditional flexibility to manufacturersand remanufacturers, EPA alsoconsidered a provision allowing alimited number of notch standards to beexceeded by a specified small amountprovided there is compliance with theduty-cycle standards. The duty-cycleweightedemissions standards and NO Xand PM notch caps considered underthis option are shown in Tables V–2through V–5 for line-haul, switch andpassenger locomotives equipped with asingle engine. Notch caps for HC andCO which are 25 percent above theapplicable line-haul duty-cyclestandards were also considered underthis option.Dual Cycle OptionThe manufacturers indicated to EPAthat it would be burdensome to complywith three sets of emission standardswhen essentially the same engine(differing only, for example, in thenumber of cylinders) could be used forall three types of locomotives (switch,passenger and line-haul). Themanufacturers’ concern is not based ontesting burden since, as discussed in thetest procedures section, the same testresults on a notch-by-notch basis aresimply weighted differently todetermine compliance with the differentstandards. Rather, the issue is one ofhaving to design three different versionsof a single engine to meet three differentsets of emission standards.The Agency believes that the linehaul/switchdual cycle approach hassome merit due to its ability to controlidle emissions from switch locomotivesas well as high notch emissions fromline-haul and passenger locomotives.However, EPA is concerned that thelack of notch caps creates a situationwhere, with the use of electroniccontrols, the duty-cycle standards canbe met during testing according to theproposed test procedure, but in-useemissions reductions are not fullyrealized. One way that this couldhappen would be if the average in-useduty-cycle changed to include greaterpercentages of time in notches whichhave disproportionately high emissions.Notch caps in individual modes wouldreduce this concern since it wouldrequire emissions control in all notches.A locomotive could also be designedsuch that the emissions duringoperation at notch eight (which areheavily weighted in the line-haul duty-