The PR30C-LE is a repowered six-axle, 2,240 kW (3,005 hp), line-haul locomotive that was introduced to the rail industry in 2009. The Caterpillar 3516C-HD Tier 2 engine is equipped with an exhaust aftertreatment module containing selective catalyst reduction (SCR) and diesel oxidation catalyst (DOC) technology. PR30C-LE exhaust emission testing was performed on test locomotive PRLX3004. Phase-1 of the test program included the following tasks: engine-out baseline emissions testing without the aftertreatment module installed, aftertreatment module installation, commissioning and degreening, and emissions testing with the aftertreatment. Emission results from testing without the aftertreatment module, referred to as the baseline configuration, indicated that PRLX3004 emissions were below Tier 2 EPA locomotive limits without aftertreatment. Emission test results with the DOC and SCR aftertreatment module showed a reduction in nitrogen oxides (NOx) of 80 percent over the line-haul cycle, and 59 percent over the switcher cycle. Particulate matter (PM) was reduced by 43 percent over the line-haul cycle and 64 percent over the switcher cycle. Line-haul cycle composite emissions of Hydrocarbon (HC) and carbon monoxide (CO) were reduced by 93 and 72 percent, respectively. The PR30C-LE locomotive achieved Tier 4 line-haul NOx, CO, HC, as well as Tier 3 PM levels. There are currently five PR30C-LE locomotives in operation in California and Arizona, and the total hour accumulation of the five PR30C-LE locomotives as of October 2011 was 20,000 hours.Copyright © 2012 by ASME