Assessing Air Quality Along San Diego's I-15 Traffic Corridor: Statistical Methods for Uncertainty Analysis

• Activity Number: 399
• Type: Contributed
• Date/Time: Thursday, August 15, 2002 : 10:30 AM to 12:20 PM
• Sponsor: Section on Statistics & the Environment*
• Author(s): Duane Steffey*+ and Janusz Supernak
• Affiliation(s): San Diego State University and San Diego State University
• Keywords: transportation ; congestion pricing ; vehicle emission rates ; traffic volume ; bootstrap ; simulation

Abstract

From 1997 to 1999, with support from the Federal Highway Administration, San Diego conducted an experimental program in which solo drivers were permitted to pay for the privilege of using the I-15 carpool lanes without carrying an additional passenger. This program continues today as the I-15 FasTrak program. Researchers at SDSU conducted a three-year monitoring and evaluation project to assess the program's impact on a variety of outcomes related to traffic and travel behavior.

We consider the task of estimating the level of automotive emissions along the I-15 corridor and developing associated estimates of standard errors. The ultimate goal is to assess whether introduction of the FasTrak program affected air quality along I-15. Various factors affect automotive emission levels, including volume and speed of traffic, types of vehicles involved (e.g., cars vs. light trucks), and individual variation within vehicle type. In conducting the uncertainty analysis we confront several challenges arising from practical limitations in the available data. The talk discusses the use of smoothing, imputation, bootstrap, and simulation methods to execute a first-order assessment.