AlternativeRouteIntersection  
    Valid only until RoutesObserver or NavigationRouteAlternativesObserver fires again.
Parameters
location
intersection point between the primary and alternative route
geometryIndexInRoute   
geometry index of the intersection point (based on referenced route's geometry)
geometryIndexInLeg   
geometry index of the intersection point (based on referenced route leg's geometry)
legIndex 
index of the leg where the intersection point is found (based on the referenced route)