Friday Seminar - Robert Campbell on Failure to Yield: A Framework for Evaluation of Compliance Measures

Traffic Circle Trails

This week's Friday TRANSOC Seminar features Robert Campbell, Ph.D. candidate, University of California, Berkeley, presenting "Failure to Yield: A Framework for Evaluation of Compliance Measures."

In this presentation, we explore the safety problem of drivers violating yield signs in a freeway context. Drivers violating traffic controls is a common problem, and agencies have a collection of strategies that they often use to address the problem. These include increasing the size of the traffic control, adding an advanced warning upstream, installing pavement markings, or using LEDs to capture drivers' attention. As common as these (and other) compliance measures are, however, no research has been done to properly evaluate how they compare in terms of effectiveness.

In cooperation with Caltrans, two different compliance strategies—increasing the size of the control, and adding supplemental pavement markings—were implemented on Interstate 10 in Los Angeles so that the effectiveness of each could be measured in the field. Although our experiments involve yield sign violations, the insights obtained can be adapted to other contexts as well, such as pedestrian crosswalks or turn prohibitions at intersections.

We will explore the outcomes of these two experiments and, using a method we have developed to allow for responsible comparisons of effectiveness, will come to conclusions about the performance of each one. Our analysis offers insights into the mechanisms behind the observed behavioral response that occurs in drivers over time after a strategy is implemented (including what happens in the often-ignored "unstable" or "novelty" phase), which we can then use to inform our assessments of each compliance strategy. Our results will reveal flaws with the conventional before-and-after approach used to evaluate compliance measures, and will show how such errors can be avoided or corrected.

 The seminar will be held in 534 Davis Hall from 4:00-5:00 on Friday, April 27. Please join us for a TRANSOC-sponsored Cookie Hour in the ITS Library, 412 McLaughlin, from 3:30-4:00.