You could put the parameters in an array and then call a color setting function for each array member.
Code:
Sub Main()
Dim features(2, 50)
features(0, 0) = "A0" : features(1, 0) = 4.5
features(0, 1) = "A1" : features(1, 1) = 4.6
features(0, 2) = "A2" : features(1, 2) = 4.9
Dim i As Integer = 0
For i = 0 To 50
SetFeatureColor(features(0, i), features(1, i))
Next i
End Sub
Function SetFeatureColor(featureID, thickness)
Select Case thickness
Case thickness < 3.1
Feature.Color(featureID) = ("Red")
Case thickness >= 3.1 And thickness < 6.0
Feature.Color(featureID) = ("Orange")
Case thickness >6
Feature.Color(featureID) = ("Green")
End Select
End Function