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Human Factors Guidelines for Road Systems - Collection C: Chapters 16, 17, 18, 19, 20, 22 (Tutorials 4, 5, 6), 23 (Updated), 24, 25, 26 (Updated) (2010) / Chapter Skim
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When to Use Changeable Message Signs
Pages 37-38

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From page 37...
... ) To display essential information about: ­ Random unpredictable incidents such as crashes ­ Temporary, pre-planned activities such as construction ­ Environmental problems such as snow ­ Special event traffic such as for parades ­ Special operational problems such as reversible lanes ­ Recurrent problems such as travel times due to congestion ­ AMBER alerts or emergency security incidents To display messages for less than 2 weeks.
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From page 38...
... . CMS reading times are higher than those for static signs because drivers can scan static signs for essential information whereas they must read the entire CMS to understand its message.
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Key Terms

  • message signs
  • static signs
  • unusual conditions
  • message sign
  • message length

  • safety campaign
  • empirical data
  • essential information
  • expert judgment
  • conditions exist

  • variable message
  • traveler information
  • include highway
  • portable variable
  • display essential

  • advisory radio
  • control measures
  • sign operation
  • policy memorandum
  • guideline recommends

  • highway advisory
  • design issues
  • recommends displaying
  • following guidelines
  • entire cms

  • factors including
  • cause reduced
  • graduate student
  • information units
  • tell drivers


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