This study examined the overall benefits of the Green Light program and extrapolated the results to estimate impacts at weigh stations across the state.
On June 17, 2008 a field test was conducted. The Oregon DOT supplied and operated a Class 8 diesel powered truck (2004 Volvo D12) configured with a lowboy trailer carrying steel plate having a gross weight of 51,700 pounds. The test area included the Woodburn weigh station and a section of I-5 from the Aurora/Donald interchange at milepost 278 to the Woodburn interchange at milepost 271. A Portable Emission Measurement System (PEMS) was used to measure fuel consumption and emissions of Nitrogen oxides (NOx) Carbon monoxide (CO) Carbon dioxide (CO2) and particulate matter (PM10 or less). Emission measurements were collected at highway speeds and transitional speeds at weigh stations. Data were collected on ten highway segments and five weigh station segments. The impacts of pre-clearance were quantified.
The results indicated that a million bypasses can result in reduced emissions of approximately 5.5 tons NOx, 0.6 tons hydrocarbons, 1.6 tons CO, 0.3 tons PM, and 875 metric tons CO2. Since approximately 1.5 million bypasses were
processed by the entire Green Light program in 2008, total annual emission reductions were estimated at 8 tons NOx, 1 ton hydrocarbons, 2.4 tons CO, and 0.5 tons PM.