Agenda - Planning Commission - 06/05/2008

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Faustman (California. Route 40) Field Study (1961)4 and Federal Highway Administration, Reanalysis of Faustman Field Study (1973)5 Two studies that appear to have stood the test oftinie are Faustrnan's original analysis of California Route 40 and its ie-examination by FHW A more than a decade later. The original analysis tried t6 improve upon previous research by limiting variables, such as- roadway geometric design and roadway access controls. The FHW A reanalysis focused on disaggregating the data and converting actual crashes to expected crash rates on specific roadway sections. Each of the sections was given a value based on the number of billboards on the section. A linear regression was performed to determine the expected crash rates. An analysis of variance of the regression coefficients found that the number of billboards. on a section was statistically significant. The reanalysis found a strong correlation between the number of billboards and crash rates as shown in Table 1. Table 1. FHWA Reanalysis ofFaustman's Findings. Expected No. of Accidents in a 5-year Period 5.92 6.65 7.38 8.11 8.84 9.57 No. of Billboards Cumulative Increase in Accident Rate o 1 2 12.3 24.2 37.0 49.3 61.7 .., .) 4 5 Federal Highway Administration Safety and Environmental Design Considerations in the Use of Commercial Electronic Variable-Message Sign age (Wachtel & Netherton, 1980) 6 This extensive review provides a comprehensive discussion of roadside advertising research as of 1980. The study authors noted "attempts to quantify the impact of roadside advertising on traffic safety have not yielded conclusive results." The authors found that courts typically rule on the side of disallowing billboards because of the "readily understood logic that a driver cannot be expected to give full attention to his driving tasks when he is reading a billboard." Because the distraction evidence is not conclusive, these decisions were generally not based on empirical evidence. The research review noted that accident reports often cite "driver distraction" as a default category used by uncertain law enforcement officers who must identify the cause of a crash. As a result, the authors believe crashes due to driver distraction are not always properly identified. In addition, law enforcement officers often fail to indicate the precise crash locations on crash reports, making it difficult to establish relationships between crashes and roadside features. . AS 64