Conditional restricted turns based on vehicle length

Discussion created by robertlindquist on Aug 21, 2012
Latest reply on Aug 22, 2012 by pstevens-esristaff
I want to restrict turns at particular intersections if a vehicle is greater than a specified length.  In other words,  any vehicle over 65 feet cannot turn left or right, but driving straight through the intersection is OK.  Further, any vehicle under 65 feet can turn in any direction.

My approach is:  In the network dataset, first I created a new feature class (named:  LengthTurnRestrictions).  I have created turn features, snapping them to the edges of the network (see the illustration below).  I added a field to the attribute table named "LengthRestiction" and have coded all of these new features as LengthRestriction = "TRUE". 


In the Network dataset properties, I have created a turn restriction attribute (named: LengthTurnRestriction).  I've also created a network attribute parameter (named: VehicleLength and set the default value to 0).  Finally, I know that I need to set the attribute evaluator to use that parameter, but I'm not sure exactly what to do. 

My thought was to set the evaluator Type be set to VB Script and the value "restricted" using VB script like: 
Select Case UCase([LengthTurnRestriction])
  Case "TRUE":restricted =TRUE
End Select

This did not work as I'd hoped.  Please comment about my approach, or better yet, let me know just what I need to do to enforce length-based turn restrictions.