I wonder how the mixture and covering will stand up to millions of crossings, at all kinds of temperatures? Does the covering turn brittle, like most materials after cooling, heating, stretching and being exposed to sunlight? Does the mixture remain uniform over time and at different temperatures, so slow drivers don't get a surprise? Can it withstand the sideways force when someone suddenly brakes while passing it? Will it withstand the rare passing of an extremely heavy vehicle, like a tank or special transport? Is it easily sabotaged?
Putting these in Ann Arbor or Tuscon would be the best test. How does it fair in freeze/unfreeze daily cycling like in Michigan? Hows the rubber stuff work in Tuscon where you really can fry an egg on the sidewalk? What's the cost benefit to cash pinched cities, the maintenance, etc? What happens when bored teens try to drain it or inflate it with bottle-rockets? Does the goop damage paint? ETC.
I feel this is a Silicon Valley 'Problem' where everyone else has much tougher/different ones than the Redwood City slogan of 'Climate Best By Government Test.'
