A risk regression system for an on-demand transportation service, comprising: one or more processors; and one or more memory resources storing instructions that, when executed by the one or more processors, cause the risk regression system to: receive, over one or more networks, transport requests from requesting users within a given region, each of the transport requests indicating a pick-up location and a destination; for each transport request, obtain a set of possible routes between the pick-up location and the destination; for each transport request, based on the set of possible routes between the pick-up location and the destination, compute an aggregate risk quantity for each possible route in the set, each aggregate risk quantity comprising a set of fractional risk quantities of respective path segments of a route; determine, based on the aggregate risk quantity, which software version running on autonomous vehicles (AVs) is authorized for execution on the respective path segments of route; and determine whether to enable the AVs to service the transport request based on the aggregate risk quantities and the software version running on the AV, wherein, where the software version running on the AV is not authorised to service the respective path segments of the route, authorize the use of a new software version for execution on the AV that is authorized for use on the respective path segments of the route. one or more processors; and one or more memory resources storing instructions that, when executed by the one or more processors, cause the risk regression system to: receive, over one or more networks, transport requests from requesting users within a given region, each of the transport requests indicating a pick-up location and a destination; for each transport request, obtain a set of possible routes between the pick-up location and the destination; for each transport request, based on the set of possible routes between the pick-up location and the destination, compute an aggregate risk quantity for each possible route in the set, each aggregate risk quantity comprising a set of fractional risk quantities of respective path segments of a route; determine, based on the aggregate risk quantity, which software version running on autonomous vehicles (AVs) is authorized for execution on the respective path segments of route; and determine whether to enable the AVs to service the transport request based on the aggregate risk quantities and the software version running on the AV, wherein, where the software version running on the AV is not authorised to service the respective path segments of the route, authorize the use of a new software version for execution on the AV that is authorized for use on the respective path segments of the route. receive, over one or more networks, transport requests from requesting users within a given region, each of the transport requests indicating a pick-up location and a destination; for each transport request, obtain a set of possible routes between the pick-up location and the destination; for each transport request, based on the set of possible routes between the pick-up location and the destination, compute an aggregate risk quantity for each possible route in the set, each aggregate risk quantity comprising a set of fractional risk quantities of respective path segments of a route; determine, based on the aggregate risk quantity, which software version running on autonomous vehicles (AVs) is authorized for execution on the respective path segments of route; and determine whether to enable the AVs to service the transport request based on the aggregate risk quantities and the software version running on the AV, wherein, where the software version running on the AV is not authorised to service the respective path segments of the route, authorize the use of a new software version for execution on the AV that is authorized for use on the respective path segments of the route. <EOS>