A driver assistance system for a vehicle, the driver assistance system comprising: a user interface to receive input from a user; a processor; and a storage device storing instructions executable by the processor to: determine a route for the vehicle to travel, the route including one or more route segments; and for each of the one or more route segments in the route, select, from a plurality of candidate route segments, those route segments having a respective route segment quality greater than a threshold, the route segment quality being based on sensor inputs from one or more sensors (504, 505, 506) indicating an observed condition of the route segment and the route segment quality subsequently being adjusted based on user input, the user input including a health condition of the user, and the user input being received from the user via the user interface, wherein the observed condition of the route segment depends on at least one of a type, frequency and amplitude of road irregularities in the route segment, and wherein the health condition of the user is indicated in terms of a tolerance of the user to road irregularities, and/or the health condition is indicated by inputting the health condition itself and determining the way in which road irregularities affect the health condition. a user interface to receive input from a user; a processor; and a storage device storing instructions executable by the processor to: determine a route for the vehicle to travel, the route including one or more route segments; and for each of the one or more route segments in the route, select, from a plurality of candidate route segments, those route segments having a respective route segment quality greater than a threshold, the route segment quality being based on sensor inputs from one or more sensors (504, 505, 506) indicating an observed condition of the route segment and the route segment quality subsequently being adjusted based on user input, the user input including a health condition of the user, and the user input being received from the user via the user interface, wherein the observed condition of the route segment depends on at least one of a type, frequency and amplitude of road irregularities in the route segment, and wherein the health condition of the user is indicated in terms of a tolerance of the user to road irregularities, and/or the health condition is indicated by inputting the health condition itself and determining the way in which road irregularities affect the health condition. determine a route for the vehicle to travel, the route including one or more route segments; and for each of the one or more route segments in the route, select, from a plurality of candidate route segments, those route segments having a respective route segment quality greater than a threshold, the route segment quality being based on sensor inputs from one or more sensors (504, 505, 506) indicating an observed condition of the route segment and the route segment quality subsequently being adjusted based on user input, the user input including a health condition of the user, and the user input being received from the user via the user interface, wherein the observed condition of the route segment depends on at least one of a type, frequency and amplitude of road irregularities in the route segment, and wherein the health condition of the user is indicated in terms of a tolerance of the user to road irregularities, and/or the health condition is indicated by inputting the health condition itself and determining the way in which road irregularities affect the health condition.