AreaAlongRoute

The width of the route corridor (must be at least MIN_CORRIDOR_WIDTH and at most MAX_CORRIDOR_WIDTH). This is the distance between the edges of the corridor. The 'corridor' is defined as the sum of the areas to the left and to the right of the central route polyline. corridorWidth measures its total width. Another way to think about this is to say that the corridor consists of all places within corridorWidth / 2 of the central route polyline, in all directions equally.

Minimum length of the route corridor (a non-negative value). This is minimum distance from the start point of the route where the algorithm is guaranteed to prefetch tiles. E.g., on a 200 km route, we will prefetch at least the first corridorMinLength. Updating the route's current position will effectively move the sliding window. The larger the area, the more robust the system is to temporary unavailability of the map data source, but this comes at a greater memory and bandwidth cost.