2011

In Map Explorer, right-click a network
topology ➤ Analysis ➤ Network Analysis
Task Pane
Network Topology Analysis - Select Method dialog
box
Dialog Box
Performing a Flood Trace
An analysis that looks out from a point in all directions is called a network
flood trace. You can perform a flood trace on a network topology, which is
made up of drawing objects and their relationship data.
NOTE This functionality applies only to drawing objects. There is no equivalent
for geospatial feature data.
You specify the point where the network starts and the maximum distance
the network can traverse. The analysis determines how many links and nodes
can be traveled before the accumulated resistance exceeds the specified
maximum resistance. For example, you might want to find all restaurants
within a 10-minute walk of a hotel.
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.
Using Flood Trace to Test Network Integrity
You can use flood trace analysis to check the integrity of a network topology.
If some links are not flooded, the topology is incomplete; you can use the
map editing tools to correct the geometry, and then recreate the topology.
Travel Time in Network Topologies
To carry out network flood trace analysis on a road network based on time
rather than distance,
assign a speed or speed limit to each link (page 849) using
an object data field or a field in a linked external database. You then set the
Link Direct Resistance parameter to an AutoLISP expression that uses this
speed limit data.
For example, to determine a flood trace analysis based on a maximum travel
time, start a flood trace, select the start point for the analysis, enter the
Performing a Flood Trace | 1333