News>>Weekly Seminar

November 20, 2009: 212 O'Brien

"Empirical Macroscopic Evaluation of Freeway Merge-Ratios"Presented by Soyoung (Sue) Ahn, Assistant Professor, Arizona State University, Department of Civil, Environmental and Sustainable Engineering

This study is concerned with the macroscopic merging behavior of traffic at fully congested freeway merges, where a queue is present at all (upstream and downstream) approaches. An existing theory states that this behavior is dictated by a fixed ratio between the two upstream merging flows, denoted as the merge-ratio. It has been further conjectured that the merge-ratio is equal to the capacity-ratio. This presentation presents an effective method to estimate merge-ratios from extensive historical traffic data. The archived traffic data in the California PEMS (Performance Measurement System) from January 2004 to June 2008 are used to estimate merge-ratios at fifteen different freeway-to-freeway merge sites (via connectors). Findings show that merge-ratios can be reasonably estimated by the ratios between the numbers of lanes on the merging approaches (lane-ratio), which is typically similar to the capacity-ratio. However, residual differences between merge-ratios and lane-ratios suggest that there are probably other influencing factors.

Soyoung Ahn is an Assistant Professor in Civil, Environmental and Sustainable Engineering at Arizona State University. Prior to joining ASU in August 2006, she received her Ph.D. (2005) in Civil and Environmental Engineering from the University of California, Berkeley and worked as a Postdoctoral Research Associate in the Department of Civil and Environmental Engineering at Portland State University, Oregon. Her expertise lies in traffic operations, Intelligent Transportation Systems applications in transportation, and traffic safety. Her research has been published in internationally-recognized journals and conferences such as Transportation Research and Accident Analysis and Prevention and has also been presented at numerous academic institutions and conferences.

Friday from 4 to 5 p.m. in 212 O'Brien on the UC Berkeley Campus, preceded by Cookie "Hour," 3:30 p.m. in the Harmer E. David Transportation Library, 4th Floor, McLaughlin Hall.

Open to the public and free.

Sponsors include the Transportation Graduate Students' Organizing Committee (TRANSOC), GA, the Institute of Transportation Studies, the University of California Transportation Center and the Department of Civil and Environmental Engineering, University of California at Berkeley.

(Previous Seminar announcements in the ITS News Archive.)