Automatic Turntable Extraction and Impedance Caluclation Tool for ArcGIS 9.2

1. Automatic Turntable Extraction and Impedance Caluclation Tool for ArcGIS 9.2 Melissa J Rura Eugene Rura Jackie Carr AAG 04/17/2007

2. Junction edge1 edge2 J1 e1 e2 J1 e1 e3 Introduction • What is a turntable? • List of edges with a common junction • Why is it necessary? • Accuracy of drive time calculation • Purpose of the project • Automation

3. Methodology • Description of input data • Network Dataset within a geodatabase • Simplified dataset • Intersection example • Required output

4. Step 1a- Calculate Turn Direction • Calculate the azimuth of both edges in the turn • Find the angle between the two azimuths • Test for direction by: If then is a right turn; assign 10 second turn time Else If then is straight; assign 15 seconds to turn time Else If then is a left turn; assign 35 seconds to turn time Else If then is a u-turn; assign -95 seconds to turn time back

5. Step 1b- Extract turns

6. Step 2 – Impedance Calculator

7. Simple 2 Intersection Example

8. Conclusion and Future Work • Include a step 3 where individual junctions or edges could be queried both spatially and by attribute to refine impedance locally • Include scientific operators in calculator such as log and exp