Multiple route pre-calculation and presentation for a vehicle navigation system

A computer-implemented navigation method for instructing an operator of a vehicle, the method comprising:

• generating, at a computer system having a processor, a proposed route to a destination location;
• pre-calculating, with the processor, before the vehicle reaches an approaching driver decision point of the proposed route, an alternate route between the approaching driver decision point and the destination location, wherein the alternate route is different than the proposed route;
• comparing the proposed route to the alternate route to obtain a route comparison;
• determining a difference metric value associated with the route comparison;
• utilizing the difference metric value to:
• calculate whether a first approaching maneuver of the alternate route, at the approaching driver decision point, is optional;
• calculate whether the first approaching maneuver of the alternate route, at the approaching driver decision point, is highly recommended;
• calculate whether the first approaching maneuver of the alternate route, at the approaching driver decision point, is mandatory;
• and
• generate indicia of the importance of a driving maneuver associated with the approaching driver decision point based upon the calculating steps;
• wherein the relative importance indicator comprises:
• a first volume of announcements of the first approaching maneuver when the first approaching maneuver is optional;
• a second volume of announcements of the first approaching maneuver when the first approaching maneuver is highly recommended;
• and
• a third volume of announcements of the first approaching maneuver when the first approaching maneuver is mandatory;
• wherein the first volume comprises a low volume, the third volume comprises a high volume, and the second volume comprises a volume level between the low volume and the high volume;
• and
• presenting, to the operator of the vehicle the indicia of the importance of a driving maneuver associated with the approaching driver decision point, wherein the driving maneuver is recommended by the proposed route.

A navigation system for instructing an operator of a vehicle, the system comprising:

• a navigation processor configured to obtain a destination location, and to generate a proposed route to the destination location, the proposed route defined by one or more driver decision points and associated driving maneuvers;
• and
• a display element coupled to the navigation processor, the display element configured to render a graphical representation of at least one segment of the proposed route;
• wherein:
• before the vehicle reaches an approaching driver decision point of the driver decision points, the navigation processor:
• pre-calculates an alternate route between the approaching driver decision point and the destination location;
• determines a relative importance indicator for the alternate route, by:
• calculating whether a first approaching maneuver of the alternate route, at the approaching driver decision point, is optional;
• calculating whether the first approaching maneuver of the alternate route, at the approaching driver decision point, is highly recommended;
• calculating whether the first approaching maneuver of the alternate route, at the approaching driver decision point, is mandatory;
• and
• generating the relative importance indicator based upon the calculating steps, wherein the relative importance indicator conveys a condition of importance for the first approaching maneuver of the alternate route, and wherein the relative importance indicator is configured for communication to a user;
• wherein the relative importance indicator comprises:
• a first tone of announcements of the first approaching maneuver when the first approaching maneuver is optional;
• a second tone of announcements of the first approaching maneuver when the first approaching maneuver is highly recommended;
• and
• a third tone of announcements of the first approaching maneuver when the first approaching maneuver is mandatory;
• wherein the first tone comprises a low degree of authoritative tone, the third tone comprises a high degree of authoritative tone, and the second frequency comprises a degree of authoritative tone between the low degree and the high degree;
• communicates the relative importance indicator to the operator of the vehicle;
• and
• activates the alternate route when the vehicle diverts from the proposed route at the approaching driver decision point.