A computer-implemented method of performing routing in a multi-modal transportation network represented using a plurality of segments, each being indicative of a navigable segment of the network, and each segment having data indicative of a traversal time for the segment associated therewith, wherein the plurality of segments representative of the multi-modal transportation network includes: a first subset of segments indicative of a first transportation sub-network of the multi-modal transportation network, the first transportation sub-network being a network which may be joined, left and travelled through by a user only at specific times; and a second subset of segments indicative of a second transportation sub-network of the multi-modal transportation network, the second transportation sub-network being a network which may be joined, left and travelled through by a user substantially at any time, the traversal time data associated with at least some of the first subset of the plurality of segments indicative of navigable segments of the first transportation sub-network of the multi-modal transportation network being based on a transit time indicative of a time taken to travel along the segment, and an additional time based on a frequency at which travel along the segment occurs, the method comprising: performing a route search between an origin and a destination within the multi-modal transportation network using the traversal time data associated with the segments of the multi-modal transportation network in order to obtain one or more possible multi-modal route from the origin to the destination through the multi-modal transportation network, determining a more accurate traversal time for the or each possible multi-modal route using data indicative of a schedule for the first transportation sub-network. a first subset of segments indicative of a first transportation sub-network of the multi-modal transportation network, the first transportation sub-network being a network which may be joined, left and travelled through by a user only at specific times; and a second subset of segments indicative of a second transportation sub-network of the multi-modal transportation network, the second transportation sub-network being a network which may be joined, left and travelled through by a user substantially at any time, the traversal time data associated with at least some of the first subset of the plurality of segments indicative of navigable segments of the first transportation sub-network of the multi-modal transportation network being based on a transit time indicative of a time taken to travel along the segment, and an additional time based on a frequency at which travel along the segment occurs, the method comprising: performing a route search between an origin and a destination within the multi-modal transportation network using the traversal time data associated with the segments of the multi-modal transportation network in order to obtain one or more possible multi-modal route from the origin to the destination through the multi-modal transportation network, determining a more accurate traversal time for the or each possible multi-modal route using data indicative of a schedule for the first transportation sub-network. performing a route search between an origin and a destination within the multi-modal transportation network using the traversal time data associated with the segments of the multi-modal transportation network in order to obtain one or more possible multi-modal route from the origin to the destination through the multi-modal transportation network, determining a more accurate traversal time for the or each possible multi-modal route using data indicative of a schedule for the first transportation sub-network.