2011

Table Of Contents

Using SQL Data in Expressions

If you specify an expression that uses SQL data, the Link Template list includes

only link templates for the drawing where the topology is loaded:

■ In the source drawing, if you loaded the topology from source drawings

■ In the current drawing, if you loaded the topology from the current

drawing.

Travel Time in Network Topologies

To carry out network path trace analysis on a road network based on time

rather than distance, assign a speed or speed limit to each link using an object

data field or a field in a linked external database. You then set the Link Direct

Resistance property to an expression that uses this speed limit data, for

example:

(/ .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).

The resulting analysis shows the shortest route, in terms of time, not distance,

to get from the first point to the second.

Tell me more

Video

■ Show me how to find the shortest path

between two points.

Procedures

■ To perform a shortest path trace (page

1326)

GIS Skills

■ Find the shortest path through a net-

work.