Various technologies pertaining to authenticating a password in a manner that prevents offline dictionary attacks are described. A bitfield placement data structure 33 describing how the bitfield index representation is partitioned is then prepared together with a maximum value data structure 32 indicating the maximum index dimension values to be used for the kernel. Vertically spaced side straps loop around the side rail structures to correlate with the cross rails and have coupler ends. The collision avoidance system is operable to generate an alert to the driver of the vehicle at a threshold time before the determined collision with the pedestrian.