I several problems. First training: My recollection is that requirements for drivers of agricultural vehicles are laxer than for drivers of other similar vehicles. Second unguarded crossings: Agricultural vehicles are much more likely to be crossing tracks at crossings that lack lights, let alone gates. Finally, the two come together with the problem of perception - large objects appear to be moving at a slower speed than smaller objects moving at the same speed. Without warning lights and without adequate training, there is a much greater chance of thinking that there is enough time to safely cross. Of course, there are also problems of machismo - us white folks have it too - and piece work pay.