(a) Locomotive testing over a ramped modal cycle is intended to improve measurement accuracy at low emission levels by allowing the use of batch sampling of PM and gaseous emissions over multiple locomotive notch settings. Ramped modal cycles combine multiple test modes of a discrete-mode steady-state into a single sample period. Time in notch is varied to be proportional to weighting factors. The ramped modal cycle for line-haul locomotives is shown in Table 1 to this section. The ramped modal cycle for switch locomotives is shown in Table 2 to this section. Both ramped modal cycles consist of a warm-up followed by three test intervals that are each weighted in a manner that maintains the duty-cycle weighting of the line-haul and switch locomotive duty cycles in §1033.530. You may use ramped modal cycle testing for any locomotives certified under this part.

(b) Ramped modal testing requires continuous gaseous analyzers and three separate PM filters (one for each test interval). You may collect a single batch sample for each test interval, but you must also measure gaseous emissions continuously to allow calculation of notch caps as required under §1033.101.

(c) You may operate the engine in any way you choose to warm it up. Then follow the provisions of 40 CFR part 1065, subpart F for general pre-test procedures (including engine and sampling system pre-conditioning).

(d) Begin the test by operating the locomotive over the pre-test portion of the cycle. For locomotives not equipped with catalysts, you may begin the test as soon as the engine reaches its lowest idle setting. For catalyst-equipped locomotives, you may begin the test in normal idle mode if the engine does not reach its lowest idle setting within 15 minutes. If you do start in normal idle, run the low idle mode after normal idle, then resume the specified mode sequence (without repeating the normal idle mode).

(e) Start the test according to 40 CFR 1065.530.

(1) Each test interval begins when operator demand is set to the first operator demand setting of each test interval of the ramped modal cycle. Each test interval ends when the time in mode is reached for the last mode in the test interval.

(2) For PM emissions (and other batch sampling), the sample period over which emissions for the test interval are averaged generally begins within 10 seconds after the operator demand is changed to start the test interval and ends within 5 seconds of the sampling time for the test mode is reached (see Table 1 to this section). You may ask to delay the start of the sample period to account for sample system residence times longer than 10 seconds.

(3) Use good engineering judgment when transitioning between test intervals.

(i) You should come as close as possible to simultaneously:

(A) Ending batch sampling of the previous test interval.

(B) Starting batch sampling of the next test interval.

(C) Changing the operator demand to the notch setting for the first mode in the next test interval.

(ii) Avoid the following:

(A) Overlapping batch sampling of the two test intervals.

(B) An unnecessarily long delay before starting the next test interval.

(iii) For example, the following sequence would generally be appropriate:

(A) End batch sampling for Interval 2 after 304 seconds in Notch 5.

(B) Switch the operator demand to Notch 6 one second later.

(C) Begin batch sampling for Interval 3 one second after switching to Notch 6.

(4) If applicable, begin the smoke test at the start of the first test interval of the applicable ramped modal cycle. Continue collecting smoke data until the completion of final test interval. You may perform smoke measurements independent of criteria pollutant measurements by rerunning the test over the duty cycle. If you choose this option, the minimum time-in-notch is 3.0 minutes for duty cycles in which only smoke is measured. Refer to §1033.101 to determine applicability of the smoke standards and §1033.525 for details on how to conduct a smoke test.

(5) Proceed through each test interval of the applicable ramped modal cycle in the order specified until the test is completed.

(6) If you must void a test interval, you may repeat it. To do so, begin with a warm engine operating at the notch setting for the last mode in the previous test interval. You do not need to repeat later test intervals if they were valid. (Note: You must report test results for all voided tests and test intervals.)

(7) Following the completion of the third test interval of the applicable ramped modal cycle, conduct the post-test sampling procedures specified in 40 CFR 1065.530.

(f) Calculate your cycle-weighted brake-specific emission rates as follows:

(1) For each test interval j:

(i) Calculate emission rates (Eij) for each pollutant i as the total mass emissions divided by the total time in the test interval.

(ii) Calculate average power (Pj) as the total work divided by the total time in the test interval.

(2) For each pollutant, calculate your cycle-weighted brake-specific emission rate using the following equation, where wj is the weighting factor for test interval j:

(g) The following tables define applicable ramped modal cycles for line-haul and switch locomotives:

[81 FR 74007, Oct. 25, 2016]