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About Sign Prediction Groups

  • Prediction Groups for Signs include the ability to define performance curves for Legend Ra and Background Ra condition categories. These curves are used to estimate sign retroreflectivity (Ra).
  • When editing the Points of either of these curves, an additional column for estimated Ra value by year is available. An Ra value and Index value are required for each year.
  • The Legend Ra and Background Ra performance curves are used to calculate the following fields on a sign record:
    • Estimated Legend Ra
    • Estimated Background Ra
    • Estimate Contrast Ratio
    • Estimated Ra State
  • Legend Ra and Background Ra are included as part of a Sign's Estimated OCI when these performance curves exist. 
  • If your organization does not utilize measured sign retroreflectivity as an assessment method, clear all points for the Legend Ra and Background Ra curves.
  • If retroreflectivity is measured on only a subset of signs. such as Regulatory signs, only the Prediction Groups which apply to those signs should include performance curves for Background Ra and Legend Ra. If readings are only taken on the background and not the legend, points should only exist on the Background Ra curve and not the Legend Ra curve. 
  • Including Background Ra and Legend Ra curves for signs that do not utilize these measures skew estimated OCI results. Estimated OCI calculations continue to function without a Background Ra curve or a Legend Ra curve.

For example, Sample A—White on Green—uses this filter:

((([Sheeting Material\ASTM Type] = 4) OR ([Sheeting Material\ASTM Type] = 7)) AND (([MUTCD Code\Background Color] starts with “Green”) AND ([MUTCD Code\Legend Color] starts with “White”)))

For each Condition Category, enter the Age and Index. If this is for the Background Ra or Legend Ra condition category, enter an Ra value. For example:

Sheeting Material   Background Ra    
Age Index Age Index Ra

0

100

0

100

200

5

75

5

85

150

10

60

10

75

100

15

50

15

65

50

 

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