>>I've seen them experimentally over the years.
>>
>>Right now, on the 401 between Toronto and Kingston, there are segments with these devices in them. But here's the rub...
>>We have to plow our highways, which normally makes for a waste of cat's eyes. So these ones are sunken to let the plow go over them. But of course the cost of installation is way high.
>
>And what do you sow in them? :-)
>
>During road construction/alteration in the UK, sometimes they put in temporary cats' eys, esp. when a lane is temp. narrowed. I think I've seen like a gun-like structure on a construction vehicle that just fires them into the tarmac.
>
>PS is that how you guys spell "plough"?

I had typed "plough" but then realized that here the word "plow" is used, so I changed it.

Obviously, if a cat's eye has to be sunken into the road surface then it cannot be fired from a gun.