California Air Resources Board

Amendments to the In-Use Off-Road Diesel-Fueled Fleets Regulation

Introduction

The recent amendments, approved by the California Air Resources Board (CARB) in 2022 (2022 amendments) to the In-Use Off-Road Diesel-Fueled Fleets Regulation (Off-Road Regulation or regulation) incorporate the benefits of emission control technologies that have evolved since the rule was originally adopted in 2007. This fact sheet specifically reviews two key elements of the 2022 amendments:

• Expanded requirements that any added vehicles be cleaner, and
• Accelerated phase-out of older, higher-emitting engines from existing fleets.

The emission reductions achieved from the accelerated turnover of dirty vehicles coupled with the clean engine replacement requirements are critical to California’s ability to attain State Implementation Plan targets and other clean air goals.

Background

Emission stringency levels for the off-road sector engines are distinguished by the engine Tier, starting with Tier 0 being the dirtiest uncontrolled engine through the cleanest Tier 4 Final. The 2022 amendments target the phase-out of high-emitting Tier 0, 1, and 2 engines. Although these older engines only make up about one-third of the statewide fleet, they account for a consequential 60% of oxides of nitrogen emissions statewide. In fact, a single Tier 0 offroad engine has up to 80 times higher emissions per hour compared to a new Tier 4 Final engine.

On-Road Vehicles: Although primarily targeted at off-road diesel vehicles 25 horsepower (hp) and greater, the regulation also applies to a small group of on-road vehicles. These on‑road vehicles include workover rigs, as well as two-engine cranes, two‑engine water drilling rigs, and other two-engine vehicles as defined by the regulation. To account for these on-road vehicles, the schedules in Tables 2 and 3 also list an on-road engine model year (MY).

Fleet Size: The regulatory compliance dates vary by fleet size. Fleet size is determined by the summed hp of all the vehicles and engines subject to the rule under common ownership or control operating in California. Table 1 shows the total fleet hp thresholds for each fleet size category.

Engine Tier

The Off-Road Regulation restricts adding vehicles with older tier engines. The engine tier correlates with the emission standard-established by the U.S. Environmental Protection Agency (U.S. EPA) and CARB - in which the engine is certified to. CARB recommends the fleet check the emission control label on the engine for the engine tier. If the engine tier is not visible, fleets may use the U.S. EPA engine family name and CARB’s executive order in the Off-Road Certification database to determine the engine tier or contact their equipment dealer.

Requirements

The 2022 amendments require that added vehicles be cleaner than previously required and that older, dirtier engines be removed from operation.

Restrictions on Adding Vehicles [Section 2449(d)(6)]: The 2022 amendments expand the restrictions on vehicles added to a fleet, as shown in Table 2. All fleets were prohibited from adding Tier 0 vehicles beginning January 1, 2014.

Large and medium fleets: The regulation prohibited Tier 1 and Tier 2 vehicles from being added to fleets starting January 1, 2014, and 2018, respectively. The 2022 amendments further prohibit the engines that can be added to a fleet. Starting January 1, 2024, Tier 3, Tier 4 Interim (Tier 4i) and MY 2006 and older
on-road vehicles are prohibited from being added to large and medium fleets. In effect, only Tier 4 Final or cleaner engines may be added to large and medium fleets starting January 1, 2024.

Small and ultra-small fleets: The regulation prohibited Tier 1 and Tier 2 vehicles from being added to small fleets starting January 1, 2016, and 2023, respectively. Small and ultra-small fleets have a more gradual rollout of added engine restrictions. The adding of vehicles with Tier 3 engines are prohibited for small and ultra-small fleets starting in 2024. Further, Tier 4i and MY 2006 and older on-road vehicles are prohibited in 2028 for small fleets and in 2035 for ultra-small fleets.

Extend Tier 0 restriction to previously exempt vocations [Section 2449(d)(6)(H)]: Starting in 2014, Tier 0 vehicles were prohibited from being added to fleets, with three exceptions. The 2022 amendments extend the Tier 0 restriction on added engines to the previously exempted vocations. Starting January 1, 2024, Tier 0 engines are restricted from being added to all fleets, including:

• Dedicated snow removal vehicles,
• Vehicles used solely for emergency operations, and
• Job corps vehicles.

Phase-Out Provisions [Section 2449.1(c)]: The 2022 amendments require that fleets no longer operate vehicles with Tier 0, 1, or 2 off-road engines and comparable on-road vehicles over a 12-year period, between 2024 and 2036. Vehicle operation is phased-out on a progressive schedule, allowing additional time for smaller fleets to comply. Table 3 lists the engine Tier and on-road MY that are prohibited from operation in California starting January 1 of the year listed in the table.

While this document is intended to assist fleets with their compliance efforts, it does not alter or modify the terms of any CARB regulation, nor does it constitute legal advice. It is the sole responsibility of fleets to ensure compliance with the Regulation for In-Use Off-Road Diesel‑Fueled Fleets.