Factors Contributing to Median Encroachments and Cross-Median Crashes (2014) / Chapter Skim
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Pages 23-36
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From page 23... ...
23 This section presents the combined results from three recent surveys of highway agencies related to median design practices: a 2003 survey conducted as part of NCHRP Project 17-14 (47) ; a 2006 survey conducted as part of NCHRP Project 22-21 (22)
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24 Agencies responding to the 2003 survey Agencies responding to the 2006 survey Agencies responding to the 2009 survey Alabama Alabama Alaska Alaska Arkansas Arizona Arizona California Florida^ Arkansas Connecticut Georgia* California Delaware Indiana^ Colorado Florida Iowa^ Connecticut Idaho Kentucky Delaware Indiana Maryland^ Florida Iowa Massachusetts Hawaii Kentucky Michigan Indiana Maine Mississippi^ Iowa Maryland Montana^ Kansas Minnesota New Mexico Maine Mississippi North Carolina^ Maryland Missouri Ohio^ Massachusetts Montana Oregon Michigan Nebraska Rhode Island*
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25 3.3.2 Median Barrier Design Criteria Respondents were asked whether their agency uses design criteria for highway median barriers that differ from the AASHTO Roadside Design Guide (46)
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26 Agency Agency type Response Design criteria different from AASHTO Green Book Agency design criteria Alaska State Highway Agency No Arizona State Highway Agency No Georgia State Highway Agency Yes From the GDOT Design Policy Manual available through the following link: http://www.dot.ga.gov/doingbusiness/PoliciesManu als/roads/Pages/DesignPolicies.aspx 6.8. Medians–Several factors will be considered when determining the applicable median treatments, such as classification of roadway, number of lanes, base year traffic, design year traffic, posted speed limit, design speed limit, and accident/crash data.
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27 Agency Agency type Response Design criteria different from AASHTO Green Book Agency design criteria more lanes in each direction shall include positive separation of opposing traffic using a median. The type of median required shall depend on guidelines stated above.
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ze Figure 6.1 Agency Agency type Response Design criteria different from AASHTO Green Book Agency design criteria Alaska State Highway Agency No Arizona State Highway Agency Yes Our guidelines are located at: http://www.azdot.gov/highways/Roadway_Engineering/ Roadway_Design/Guidelines/Manuals/PDF/Roadway DesignGuidelines.pdf Median barriers are covered in Sections 304.4, 305, 305.9, and 305.11. Median barriers shall be installed on: a)
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29 Agency Does your agency use the 2002 AASHTO median barrier warrants? Alabama (2003)
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30 Agency Response Median barrier warrant criteria Arizona (2009) Our guidelines are located at: http://www.azdot.gov/hig hways/Roadway_Engine ering/Roadway_Design/ Guidelines/Manuals/PD F/RoadwayDesignGuide lines.pdf Section 304.4 covers median barrier warrants.
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31 Respondents were then asked what factors related to driver behavior and weather conditions played a role in median encroachments and cross-median crashes. Response frequency and rating average for each factor are shown in Table 3-10.
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32 3.3.5 Availability of Safety Evaluations and Maintenance Records Respondents were asked whether their agencies had conducted any published or unpublished safety evaluations of the factors listed above, or whether their agencies had any data to support the professional opinions given above regarding factors that contribute to median encroachment and crossmedian crashes. Of the 27 agencies that responded to the question, 10 answered yes.
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33 Agency Description of Measures Arizona Relocated median cable barrier from center of median to edge of shoulder. Florida 1.
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34 to their agency's efforts to reduce the frequency and severity of median encroachments and cross-median crashes. Comments were received from eight agencies as follows: • Arizona: Implemented speed-enforcement cameras on many of our urban freeways.
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35 Agency Are maintenance records available? Information provided about the availability of maintenance records Arizona Yes There is a spreadsheet that could be used to identify some locations with high encroachments.
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36 • Illinois State Toll Highway Authority: The Tollway has installed a network of 39 over-the-road dynamic message signs prior to all system (Interstate to Interstate) interchanges.
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