California ARB Backs Down on Diesel Engines

This week California's Air Resources Board (ARB) announced a major shift in the ongoing matter of diesel engine emissions from off-road equipment. Fleet owners had expressed grave concerns over reduced safety and increased injuries if these large diesel particulate filters (DPF) are installed, and added that existing California law would be violated. ARB acquiesced by announcing that they intend to clarify the rules, and such DPFs will not be required where their installation would impair the equipment operator's vision in any direction.

As background, ARB has an ongoing campaign to remove diesel smoke from the air, as this smoke contains particulate matter (PM10) that causes health issues. ARB divides the world into two categories, stationary and mobile sources. Within the mobile source category, ARB further divides into on-road and off-road categories (and a few others not pertinent here). On-road trucks and vehicles have had regulations in force for some time. Off-road, diesel-powered equipment such as is used for heavy construction has a regulation that goes into effect March 1, 2010, only four months away at this writing. The vendors have developed (and continue to develop) after-market devices (DPFs) that are installed after the engine's muffler. These devices use different technologies, but the basic principle is to filter or trap the small particles, and burn the particles within the device thus creating CO2 and a small amount of water vapor and NOx. Residual ash is left in the DPF and must be removed periodically.

The point of contention is blocking the equipment operator's vision due to the size of the DPFs. The larger the engine, the larger the DPF, and in some cases, large engines require two DPFs arranged in parallel flow. The DPF may be approximately 2 feet long and 10 inches in diameter. Such a device can obstruct the equipment operator's vision, which could lead to increased accidents and injuries. It is common on construction sites for workers to walk and work very near a piece of heavy construction equipment.

California has existing regulations that prevent the installation of devices on equipment that decrease the safety. Equipment designers go to great lengths to design their equipment in as safe a manner as possible, using low hoods, elevated operator seats, large windows, strong but narrow window frames, and locating the engine exhaust pipe where it will least obstruct the operator's view.

While ARB has yet to release its final regulations and the exemption for operator visibility, based on language in the announcement, it is likely that DPFs will not be required if the DPF will not fit under the hood and out of sight.

From ARB's website:

"ARB, the Occupational Safety and Health Standards Board, and the Division of Occupational Safety and Health (Cal/OSHA) have agreed on an interim policy to address retrofit visibility concerns for off-road diesel vehicles. The interim policy will exempt any vehicles that cannot be retrofit without impairing the operator’s vision to the front, sides, or rear of the vehicle from the March 1, 2010 retrofit requirement for large fleets of off-road diesel vehicles. ARB will release details regarding the method to measure visibility impairment, as well the process for applying for an exemption as soon as possible.

For more information and a background on this issue, you may view the interim policy online.

Fleets that must complete retrofits in 2010 should begin by retrofitting those vehicles for which retrofits may be installed without impacting operator visibility (for example, under the hood or out of site of the operator)."