Performing a Shortest Path Trace
Concept Procedure Quick Reference
 
 
 
NoteThis procedure applies only to drawing objects.

To perform a shortest path trace

  1. Verify that you have a network topology available and it is loaded. See Creating Topologies and To load a topology.
  2. In Map Explorer, under Current Drawing, right-click a network topology Analysis Network Analysis.
  3. In the Network Topology Analysis - Select Method dialog box, click Shortest Path. Click Next.
  4. In the Network Topology Analysis - Choose Locations dialog box, click Start Point, and then click (Select Point) to select the starting point in the map. Press Enter to return to the dialog box.

    AutoCAD Map 3D uses the node closest to the location you clicked as the start point. The coordinates of the point are shown in the list.

  5. Click End Point. To select the ending point, click (Select Point). Press Enter to return to the dialog box.

    AutoCAD Map 3D uses the node closest to the location you clicked as the end point.

  6. Review the start and end points you have specified. The coordinates of the points are shown in the list.
    • To double-check the location of a point in the map, highlight the coordinates in the list. Click Preview.
    • To delete a point so that you can define a new one, highlight the coordinates in the list. Click Delete.
  7. Click Next.
  8. In the Network Topology Analysis - Direction and Resistance dialog box, select limits to put on the trace. For direction and resistance, you can enter a constant or an expression that references an object data field or linked external database column. The expression will be evaluated for each link. Click (Expression Evaluator) to select data from a list.
    • Link Direction — Specify a direction for the trace. If you leave the box blank, bi-directional (0) is used.
    • Reverse — Select this option to use the reverse of the direction indicated in the Link Direction box.
    • Link Direct Resistance — Specify the resistance to travel in the direction that a link was created. If you leave the box blank, the length of the line (.LENGTH) is used.
    • Link Reverse Resistance — Specify the resistance in the opposite direction along a link. If you leave the box blank, the length of the line (.LENGTH) is used.
    • Node Resistance — Specify the resistance to cross the node, for example, resistance for a valve in a pipe network, or a junction in a road network. If you leave the box blank, zero (0) is used.
    • Maximum Resistance and Minimum Resistance — Any path that has a total resistance below the minimum or above the maximum is ignored.

    For example, if you stored the average speed limit for a link (in miles per hour) in an object data table called street_data, you could find the fastest route between two points by entering the expression (/ .length (* :speed@street_data 5280) which divides the length of each link by the average speed per foot (where 5280 is the number of feet in a mile).

  9. Click Next.
  10. In the Network Topology Analysis - Output dialog box, indicate whether or not to view the results of the trace onscreen and whether to save the trace results as a new topology.
    • To view your shortest path trace onscreen, select Highlight. Choose a highlight color from the Color list.

      You should use a highlight color that is different from the color of the objects in your map.

    • To save the shortest path trace as a new topology, select Create Topology. Enter a name and description for the new topology. The new topology will be created on the existing objects.
  11. Click Finish to perform the shortest path trace.