Data mining in a digital map database to identify intersections located over hills and enabling precautionary actions in a vehicle

1 . A method for making a database that represents a road network in a geographic region, the method comprising:

using data contained in the database to identify intersection located over hilltops located along roads throughout the geographic region; and

adding precautionary action data to the database to indicate a condition for which a precautionary action is to be taken by a vehicle system.

2 . The method of claim 1 further comprising:

selecting from the database a data record that represents a road segment;

upon determining that the road segment leads to an intersection located over a hilltop, adding the precautionary action data to the database to indicate the presence of a condition for which a precautionary action is to be taken.

3 . The method of claim 2 further wherein the road segment is determined to have an intersection located over a hilltop by evaluating an elevation profile associated with the road segment.

4 . The method of claim 2 further comprising:

continuing to select from the database data records that represent road segments to identify all locations of intersections located over hilltops throughout the geographic region.

5 . The method of claim 2 further comprising:

continuing to select from the database data records that represent road segments until all data records that represent road segments have been selected.

6 . The method of claim 1 further comprising:

compiling the database into a format suitable for use in a navigation system.

7 . The method of claim 1 wherein the step of using data contained in the database comprises evaluating at least two items of data contained in the database to determine whether an intersection located over a hilltop is located along a road.

8 . A database stored on a computer-readable medium, wherein the database includes data that represents a road network in a geographic region, wherein the database comprises:

data records that represent road segments and intersections that make up the road network;

data that represent an elevation profile of road segments along the road network; and

data that indicates precautionary action locations, wherein a precautionary action location is associated with a location where an intersection located over a hilltop is located along the road network.

9 . The database of claim 8 wherein the precautionary action data further includes data that indicates a location along a road segment at which a precautionary action is to be taken by a vehicle system.

10 . The database of claim 8 wherein the precautionary action data further includes data that indicates a direction along a road segment at which a precautionary action is to be taken.

11 . The database of claim 8 wherein the precautionary action data further includes data that refers to the location of the actual intersection located over a hilltop.

12 . The database of claim 8 further comprising data that indicates permitted directions of travel along road segments, speed limits along road segments, classifications of road segments, and locations of road segments.

13 . The database of claim 8 further comprising data that identifies successor road segments of each road segment, wherein successor road segments are those road segments that connect to a road segment at each end thereof.

14 . A vehicle system comprising:

a database that contains data representing a geographic region in which a vehicle is being operated, wherein the data includes data that represents a road network located in the geographic region and precautionary action data that indicates precautionary action locations associated with locations where intersections located over hilltops are located along sections of roads;

a positioning system that determines a current location of the vehicle relative to the data representing a geographic region; and

a precautionary action application responsive to the positioning system and the database that provides a precautionary action when the positioning system determines that the current location of the vehicle is approaching an intersection located over a hilltop along a road.

15 . The system of claim 14 wherein the precautionary action data further includes data that indicates a location along a road segment at which a precautionary action is to be taken by a vehicle system.

16 . The system of claim 14 wherein the precautionary action data further includes data that indicates a direction along a road segment at which a precautionary action is to be taken.

17 . The system of claim 14 wherein the precautionary action data further includes data that refers to the location of the actual intersection located over a hilltop along the road.

18 . A method for providing precautionary actions in a vehicle comprising:

determining a current position of the vehicle;

accessing a database that represents a road network to obtain data representations of a part of the road network around of the current position of the vehicle; and

upon determining that the data representations of the part of the road network around the current position of the vehicle include precautionary action data, taking a precautionary action as the vehicle is approaching an intersection located over a hilltop along a section of road.

19 . The method of claim 18 further comprising:

building an electronic horizon after accessing the database; and

using the electronic horizon to determine whether precautionary action data is included therein.

20 . The method of claim 18 wherein the precautionary action is provided via a user interface of the vehicle.