Real structures have pier and abutment widths of the order of 1-3 metres and flood flow velocities upwards of 2m/s. Thus Reynolds Number will be significantly above 10^6, which is above the critical flow transition for circular piers. This means that pier drag factor will be lower than in models with RE< 5x10^5 and there will be no coherent vortex shedding, which in scale models produces suction, lifting disturbed sediment out of the scour hole. This epistemical source of error was missed by Bateni in 2007 and does not appear to have been considered by subsequent machine learning researchers.