But good things can get better. There's been a boom in protected bike lanes in the U.S. in the past ±5 years, and most of them use parked cars or plastic poles to keep the bike lane separated from the car lanes. That works, but it's not ideal, and so the next generation of protected bike lanes have started to use more permanent curbs to protect cyclists. People for Bikes reports:
In Chicago, Clybourn Avenue and State Street are likely to get the city's first curb-separated bike lanes. In Seattle, the city has used two wholesale road reconstructions, on Linden Avenue and Broadway, as chances to install cement curb separations. In Austin, two blocks of 3rd Street downtown are now fitted with modular precast curbs to create a protected bike lane. And Long Beach, Calif., has been using curbs for protected bike lanes since 2011.
Chicago bike project manager Mike Amsden said Chicago plans to eventually upgrade all its plastic posts to permanent infrastructure. [...] The sense that a curb can fit more gracefully than posts into the feel of a street "goes a long way to selling these projects to people who may not care about bikes," Amsden added.
Many other cities are already building these, or looking into them. I know that Ottawa, Canada, close to where I live has some protected bike lanes that use curbs (though they are a bit too high, more on that below).
Make sure to use bike-friendly curbs...As commenter 'Falbo' pointed out on People for Bikes:
Curbs a great, but please use bicycle-friendly curbs. One of the subtle details of dutch and danish cycle tracks is the use of short (3") angled curbs, to maximize operating space.
Full height vertical 6" curbs are not bicycle friendly. Riders risk hitting their pedals on them, and must shy away, reducing the useful space in the cycle track. Having two full height curbs on each side of a narrow cycle track is a bad idea.
That's very important. You don't want to inadvertently create a new danger for cyclists, even if overall the curb adds security.
Via People for Bikes