Real World Emissions from Tier 4F Off-Road Construction Equipment 2022-01-0577

The primary purpose of this study was to obtain gas-phase and particular matter (PM) emissions from newer Tier 4 final off-road construction equipment using a Portable Emissions Measurement System (PEMS). This information can be used to provide accurate estimates of emissions from off-road construction equipment under real-world scenarios. Emission measurements were made for 10 pieces of Tier 4 final construction equipment including 3 excavators, 3 wheel loaders, 2 crawler tractors and 2 backhoe/loaders. The duty cycles included a pre-defined combined sequence of a cold-start phase, trenching, backfilling, travelling, and idling. For all types of equipment, the highest emissions were seen for the cold start phase, which showed NOx emissions levels ranging from 3.4 to 6.3 g/bhp-hr, from 15.8 to 26.1 g/kg-fuel and from 107 to 249 g/hour, with an average exhaust temperature around 100°C.The next highest emissions were found for the travel mode. NOx emissions from the idle period ranged from 12.8 to 50 g/hour. NOx emissions from all equipment categories over trench and backfill modes show a range from 0.07 to 0.69 g/bhp-hr, from 0.4 to 3.7 g/kg-fuel, and from 11.4 to 34.2 g/hour. NOx emissions over trench and backfill work modes were generally close to or below the in-use compliance emission rate (1.5 times engine certified emissions rate) except for a few pieces of equipment that showed higher emissions due to less effective aftertreatment systems or lower exhaust temperatures. PM emissions ranged from 0.1 to 13 mg/bhp-hr, which is below the standard of 20 mg/bhp-hr for Tier 4 final off-road equipment. The backhoe/loader category shows the highest emissions because both pieces of equipment in this category lacked a DPF to reduce PM emissions.