Abstract: When a vehicle performs route calculation at a current position, the number of lanes at the current position is found. A predetermined correspondence between the numbers of lanes and straight prioritized distances is used to find a straight prioritized distance at the current position corresponding to the number of lanes. A route to a destination from the current position is calculated so as to include, in the route, a road to be followed for the straight prioritized distance from the current position. When there are many lanes, the straight prioritized distance is set to be long. Accordingly, it is possible to avoid calculating a route that causes a guide to sudden right or left turn. When there are a few lanes, the straight prioritized distance is set to be short. Accordingly, it is possible to avoid calculating a roundabout route to the destination.

Abstract: A navigation system for providing a navigation route of a travel between a start point and an end point based on a route search by using a predetermined condition includes a display unit for displaying the navigation route and/or a navigation route candidate with a condition name associated thereto. The predetermined condition with the condition name associated thereto yields a plurality of navigation route candidates as a result of the route search.

Abstract: A first recommended route is computed as having the minimum cost from a start point to an end point as a destination. The first recommended route is then divided by using each road name. Here, Tomei Expressway occupies 60% or more in the entire traveling length of the first recommended route while National Road No. 1 occupies 10% or more in the entire traveling length of the first recommended route. A link cost of Tomei Expressway is thereby multiplied by 1.5, while a link cost of National Road No. 1 is thereby multiplied by 1.2. Another route from the start point to the end point is re-computed by using the changed link costs. A detour avoiding Tomei Expressway and National Road No. 1 is thereby designated.

Abstract: When a vehicle performs route calculation at a current position, the number of lanes at the current position is found. A predetermined correspondence between the numbers of lanes and straight prioritized distances is used to find a straight prioritized distance at the current position corresponding to the number of lanes. A route to a destination from the current position is calculated so as to include, in the route, a road to be followed for the straight prioritized distance from the current position. When there are many lanes, the straight prioritized distance is set to be long. Accordingly, it is possible to avoid calculating a route that causes a guide to sudden right or left turn. When there are a few lanes, the straight prioritized distance is set to be short. Accordingly, it is possible to avoid calculating a roundabout route to the destination.

Abstract: A first recommended route is computed as having the minimum cost from a start point to an end point as a destination. The first recommended route is then divided by using each road name. Here, Tomei Expressway occupies 60% or more in the entire traveling length of the first recommended route while National Road No. 1 occupies 10% or more in the entire traveling length of the first recommended route. A link cost of Tomei Expressway is thereby multiplied by 1.5, while a link cost of National Road No. 1 is thereby multiplied by 1.2. Another route from the start point to the end point is re-computed by using the changed link costs. A detour avoiding Tomei Expressway and National Road No. 1 is thereby designated.

Abstract: The present invention provides a desirable route that avoids particular roads where a start point or the like has been set on a particular road type. In the present invention, route evaluation values of links A and B on a toll road are multiplied by, for example, 1.0 times. Therefore, the sum of route evaluation values of a route through links A→G→D→E→F becomes 5+2+5+20+15=47 and the sum of evaluation values of a route through links B→G→F becomes 20+2+15=37. Thus, a route passing link B having a small sum of evaluation value is set as a route to the destination.

Abstract: In a vehicle navigation system, an initial recommended travel path between a departure point and a destination is determined using the Dijikstra method. If an external memory stores path information regarding a short-cut path that has its start point and end point on the recommended travel path, a corresponding part of the recommended travel path is replaced with the short-cut path to guide the vehicle along the modified recommended travel path. If the vehicle travels deviating from the recommended travel path, path information that specify the leaving path are collected and stored as a new short-cut path in the external memory. If the same travel path is searched for next time, the short-cut path thus stored is used to modify the recommended travel path.