A study of the effects of pavement widening, rumble strips, and rumble stripes on rural highways in Alabama : final report.
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A study of the effects of pavement widening, rumble strips, and rumble stripes on rural highways in Alabama : final report.

  • Published Date:

    2016-01-01

  • Language:
    English
Filetype[PDF-1.42 MB]


Details:
  • Publication/ Report Number:
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  • Edition:
    Final report
  • Abstract:
    In an effort to address this particularly frequent and severe crash type, the Alabama Department of Transportation (ALDOT) implemented a policy in February 2006 to widen pavements and install milled-in rumble strips when rural two-lane highways with less than 28 ft of pavement width are resurfaced. On the vast majority of these roadways, little or no hard-surfaced shoulder had previously existed. The policy determined that upon resurfacing, shoulders were to be strengthened, 2 ft of full-depth pavement added on each side of the roadway, and in some cases, rumble strips or stripes were scored into the pavement within the 2 ft shoulder. In practice, this policy was extended to four-lane divided rural roads and paved shoulders widths were in a range from 2 to 4 ft. The practice of pavement widening, or shoulder wedging, to provide an additional recovery area for errant vehicles leaving the travel lane but prior to leaving the pavement surface is becoming increasingly common in many states. Although this had previously been done in isolated cases in Alabama, this new policy represents a major effort to reduce roadway departure crashes on rural roadways over the next several years. Due to the level of investment associated with this policy, and its intended safety benefits, a study to quantify the potential benefits is worthy of consideration, and its findings could possibly be used to further support this initiative. The Empirical Bayes (EB) method, as outlined in the Highway Safety Manual, the equivalent property damage only (EPDO) analysis, and the benefit-cost analysis are proposed to address safety effectiveness of the countermeasures implemented in Alabama. The objectives of this study are as follows: 1. Document the state of the practice and results of prior research; 2. Estimate reduction in run-off-road (ROR) crashes, by severity, based on the data, applying both EB and EPDO methods 3. Develop crash modification factors for the following five treatments: - Paving 2 to 4 ft of unpaved shoulders on two-lane rural roads; - Combined effect of paving 2 to 4 ft of unpaved shoulder and adding rumble strips on two-lane rural roads; - Combined effect of paving 2 to 4 ft of unpaved shoulder and adding rumble stripes on two-lane rural roads; - Paving 2 to 4 ft of unpaved shoulders on four-lane divided rural roads; - Combined effect of paving 2 to 4 ft of unpaved shoulder and adding rumble strips on four-lane divided rural roads; 4. Quantify the benefits and costs of the ALDOT policy; 5. Make recommendations for future application. This report is not intended for construction, bidding, or permit purposes.
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