Oh, I like the water-wall too. But a driver who misses the 1st two no-damage physical-contact warnings I've proposed -- and thus would hit the damaging third ha

Oh, I like the water-wall too. But a driver who misses the 1st two no-damage physical-contact warnings I've proposed -- and thus would hit the damaging third hard bar -- would quite possibly ignore the water-wall too. After all, the water wall seems primarily visual, and the driver has already missed numerous visual warnings. The contact protectors add collision-noise and vibration, which are rare enough that even a dozing/road-hypnotized driver is likely to take note. Comparative testing is of course justified.