At three outdoor locations near Library Square until September 9

Permanently installed at the southern edge of George Wainborn Park

Cameron Kerr's Marble Infrastructure Project and Douglas Taylor's Khenko occupy opposite ends of the public-art spectrum. One work is all intellectual rigour: a minimalist-conceptualist undertaking that deals in mimicry, obstacle, and alienation. The other is more immediately accessible: a kinetic sculpture that addresses the relationship between its setting and the natural world. One is temporary; the other is permanent. One attracts the attention of vandals; the other, of passersby. Both, however, can claim equal measures of success and failure.

Kerr's three sets of marble sculptures were curated by Barbara Cole and Patrik Andersson as part of a program titled Other Sights for Artists' Projects. Same-size representations of concrete traffic and roadside barriers, they are temporarily installed around Library Square in downtown Vancouver: Stack (formerly Row) on the library plaza at the corner of Homer and Georgia streets; Bookends outside the Main Post Office at Georgia and Hamilton streets; and Highway Barriers on the south plaza of the Queen Elizabeth Theatre.

The relationship of form, scale, and medium to location is both provocative and problematic here. Kerr's oxymoronic tactic is to depict functional, cast-concrete objects in marble, a medium bearing the inevitable associations of classical sculpture and upscale architecture. His banal forms are reminiscent of the minimalism of the 1960s and '70s, especially the situational sculpture of Carl Andre, who in 1966 famously laid a long row of firebricks across a gallery floor. Instead of recontextualizing industrial forms by placing them inside an art gallery, however, Kerr has sought to alter their status by re-creating them in an expensive and ennobling medium.

Andre and Kerr share similar impulses: to draw our attention to the formal qualities of the quotidian and the mass-made, and to question the values assigned to art objects. They differ in that Kerr has left his sculptures outside the museum door. Unfortunately, two of his three works lack command of their locations. Highway Barriers, with its strong verticality, speaks effectively enough of government control, individual estrangement, and the ways in which dull form is enlivened by an elegant medium. But Stack and Bookends, which have both been chipped, gouged, and scraped by skateboarders, are almost mute. It's as if their sites had killed their intentions, making it too easy to pass by without noticing them. The sculptures' lack of distinction from their outdoor urban setting””they're much too quietly like the objects they depict””makes them invisible to pedestrians and vulnerable to wheeled vandals.

The day I visited Taylor's (unvandalized) Khenko, the moving components of the almost five-metre-tall work brought a group of bicyclists to an appreciative halt. Part hang glider, part anemometer, part outsize whirligig, Khenko is a donation from Concord Pacific to the Vancouver parks board. It also, noticeably, occupies one of the most prominent sites on the north shore of False Creek: a grassy mound, skirted by the seawall, on a promontory overlooking Granville Island.

Four podlike sails are mounted at the top of a steel pole, each spinning vertically on its individual axis while they all rotate, collectively and horizontally, as they catch the wind. Their movement drives the steel sculpture of a heron””a kind of line drawing in three dimensions””that hangs below, causing its wings to flap up and down. Very, very slowly. Within the belly of the bird is a cast-resin depiction of a fish.

While the upper part of the structure is elegant and graceful, reminiscent of a big Alexander Calder mobile, the bird and fish are a tad cheesy. This is unfortunate, because as an accompanying notice tells us, the work celebrates the return of the great blue heron to False Creek “after many years of industrial pollution” . More subliminally, it addresses the ways in which our built environment bumps up against the natural world. And, along with Kerr's project, the ways human beings bump up against public art, too.