UC Berkeley scientists measure diesel truck emissions in Caldecott Tunnel

Nicole White/Staff

Related Posts

A team of campus researchers is measuring the relative levels of diesel truck emissions passing through Berkeley’s Caldecott Tunnel in an effort to determine the effectiveness of California’s new emissions requirements.

The researchers, a group of scientists from the campus’s Lawrence Berkeley National Laboratory, have been using a set of cameras, monitors and a research van to gather data that describe the amounts of relative gases and diesel particulate matter emitted by the large trucks.

“We bring a bunch of air pollution analyzers we have in a research van,” said Thomas Kirchstetter, principal investigator for the project, who is also a scientist at the lab and an associate adjunct professor at UC Berkeley. “It’s a mobile laboratory.”

The study, sponsored by California’s Air Resources Board, or ARB, follows the Truck and Bus Regulation enacted by the state in 2008. The regulation requires the owners of diesel trucks and buses to either upgrade their engines to newer models or replace their filters according to their weight.

Filled with computers and an equipment rack, the van is parked at the Caldecott Tunnel entrance, where a hanging sample line connects from the van to the ceiling of the tunnel. According to Kirchstetter, when trucks with vertical stacks pass through, a fan sucks the exhaust into the sample line.

“Basically, we are sucking in the exhaust that truck has just emitted,” Kirchstetter said. “From those measurements, we can estimate emission rates.”

Robert Harley, a co-principal investigator on the research team as well as a campus professor of civil and environmental engineering, said the project measures both gases and particles using what he calls “first-response techniques” because the vehicles are moving targets.

In addition to measuring emissions, the researchers have cameras set up to identify and track individual trucks by license plate number, which are cross-checked with the ARB to determine what kind of engine and filter the vehicle has.

ARB spokesperson Karen Caesar said one of the board’s goals with the implementation of the Truck and Bus Regulation was to have California’s diesel emissions reduced by 85 percent by 2020.

The regulation was one of a few enacted after a state scientific review panel identified diesel exhaust as a toxic contaminant in 1998. The report identified a link between diesel emissions and cancer, and the state was required to address the risk, Caesar said.

Through the study, researchers and stakeholders are trying to determine the extent to which this policy change concerning emissions standards affects real-world emissions in California, according to Kirchstetter.

“(It’s) very cool work,” Kirchstetter said. “It’s nice to put a lot of effort into something that sort of has immediate practical value.”

Contact Charles Fisher at [email protected].