IN two locations, a private townhouse n'hood and a public street, I've seen them putting curbs that, instead of the typical 4" high, are 6" high with an almost square corner at the top. If you hit them with a front tire, instead of going up on the curb, it looks to me like you'll scrape your rim and/or maybe push the tire from the rim and go flat.
Have you seen these 6" curbs and what is there appeal?
And are they going to spread... I hope not.