More than 76 percent of drivers on an interstate route in northern California indicated that messages displayed by an advanced curve warning system were useful.
The evaluation consisted of a comparison of speed data gathered before and after installation of the warning system, and surveys taken approximately 2 months and 10 months after installation. Speed data were collected using stopwatches to determine the speed of vehicles approaching the curves as the vehicles traveled over measured distances. Speed measurements were collected 9 months prior to the system’s installation and again 2 months, 5 months, and 10 months after operation began. Surveys of vehicle drivers were taken at a rest area within the corridor. One hundred and fifty-three (153) truck drivers completed surveys regarding the system 2 months after it began operation and 162 completed the second survey 8 months later. Eighty-nine (89) passenger car drivers completed surveys 2 months after operation began, and 77 completed the second survey. The report also discusses the crash statistics for the curves during the five years preceding installation of the warning system, but the short evaluation period following installation makes comparison of accident statistics invalid.
Survey results indicated that truck drivers in the corridor generally drove it frequently and were familiar with the curves, while passenger car drivers were most often infrequent travelers unfamiliar with the curves. Seventy-three (73) percent of truck drivers responding to the first survey and 70 percent responding to the second survey indicated that the signs were useful. During the two visits, 76 percent and 69 percent, respectively, indicated that they reduced their speed in response to the signs. Seventy-eight (78) percent of the passenger car drivers responding to the first survey and 85 percent in the second survey stated that the system was useful. Sixty (60) percent participating in the first survey and 69 percent in the second survey indicated that they reduced their speed in response to the signs.
The authors note a potential flaw in the survey. The number of drivers who reduced their speed in response to the signs may not completely represent the effectiveness of the signs because the survey fails to assess the impact of the sign on travelers who were already traveling below the advisory speed displayed on the signs.
Author: Tribbett, Lani, et al.
Published By: California DOT
Prepared by the Western Transportation Institute and Montana State University for the California DOT New Technology and Research Program
Source Date: April 2000URL: http://www.coe.montana.edu/wti/wti/pdf/429861_Final.pdf
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