Grade Separated Crossings
Figure 22-6 shows our example enhanced by annotations describing the highway interchange. Here a Grade Separated Crossing consists of two Paths that cross but do not communicate directly with each other. In the example, it would not be possible to simply turn left from Highway 2 in order to get to Highway 14. It is necessary to take a Ramp.
Figure 22-6: A Sample Interchange
The Ramp is a Roadway Path that begins at Grade Crossing “1054-3” and ends at Grade Crossing “1054-2”. Since it is not a single highway, here the Ramp is simply labeled Ramp “2-14”. The value of its Bi-directional Indicator is clearly “False”—traffic ...