In a deserted parking lot at the 47^th Street trolley stop on Saturday afternoon, a lone woman balanced on a metal sculpture and stretched her long limbs like a human spider. Suddenly a car with two men inside cruised by. They stared at her intensely, but were they friend or foe? Would they stop to help her, or kidnap her? The suspense was chilling. But no, maybe she was just stretching, and the guys recognized her, or were simply surprised to see her there. What if the car hadn’t gone by at all? The whole scene questions our perceptions and what is real and what is illusion. Ah, the beauty of site-specific dance.

In reality, the woman was the lovely Rachel Sebastian, a principal dancer with the San Diego Ballet performing Jean Isaac’s “Two Forms,” in the eighth installation of Trolley Dances, presented by Jean Isaacs San Diego Dance Theater.

This year, the site-specific performances are especially animated, as four choreographers, Isaacs and Bradley Lundberg of San Diego, Monica Bill Barnes of New York, and Benjamin Levy of San Francisco, have tapped deep into six unique sites along the Orange Line near the culturally rich Market Creek Plaza.

Site-specific dance has tremendous power, as well as challenges. According to the dance critic Camille Lefevre, in a site-specific dance, the choreographer receives his or her “spatial dictation, directions for audience placement, and theatrical inspiration from the site itself.” Add chance events such an ice cream truck, planes flying overhead, and innocent people passing by, and you’ve got dance that is never the same. Just as significant is that with site-specific dance, the audience gets to be outdoors under glorious blue skies and becomes part of the landscape.

To take part, simply take the trolley, or drive to the trolley station Saturday or Sunday and find a friendly guide. Every 45 minutes, they lead small groups on a tour of easy walks and trolley rides throughout the surrounding neighborhood. Guards from the Metropolitan Transit System make all areas of the trolley feel secure. (On the first Saturday, Transit Authority guard Hampton even joined the last group). The first stop is an easy stroll to the Food 4 Less grocery store.

Wait! If you have not yet taken the Trolley Dances tour, stop reading now, to preserve the surprises you’ll encounter along the way. But if you’re the type that enjoys reading the last page of a book before reading the whole thing, go ahead and read on.

With choreography by Jean Isaacs, and collaboration from Kate Brill and Yvonne Harguindeguy, dancers slinked through the produce section, in a comic romp titled “Precision (sic) Produce Handling,” but it could have been called “The Secret Lives of Produce Handlers.

As passive shoppers inspected tomatoes and weighed apples, dancers dressed in official aprons and striped shirts, galloped through the aisle proudly holding giant limes. Several shoppers tried to ignore the commotion, as if it were a weird dream. But as they bagged their fruits and veggies, dancers Brill, Harguinguy, Danielle Bodeau, Kevin Jenkins, Robby Johnson, Molly Klaproth, Anjanette Maraya, and Luis Quiroz were unrelenting. They slumped forward and back, and tossed and manipulated fruits, holding them under their chins and eating them in seductive ways. Their interaction with viewers was delightfully deadpan, and without a doubt, families throughout that area will be saying, “Honey, you won’t believe what I saw at the store today.”

Site 2 was just a zigzag across the parking lot. In a small corner of the amphitheatre at market Street Plaza, dancers performed an untitled piece by Isaacs, and for a few minutes, there were no thoughts of busy, gritty streets and traffic just a few feet away. Dressed in clean white, seven dancers languished on a retaining wall like enchanted woodland nymphs. Near a bronze statue of a young boy, they rolled off the walls in slow cascades to regroup farther up the grass. A curious young boy who was not in the tour, moved very close to the action, and his mother screamed for him to return to her side. It was a glorious chance moment, where the young boy was drawn to the seemingly magical beings. Dancers included: Katie Engbring, Amber Hamer, Sarah Hogan, Liv Isaacs-Nollet, Christiane Marshall Kathryn McCann, and Donna Webb.

The tour continued with a walk across the trolley tracks and Market St. to a secret spot behind a chain-link fence, home of the Writerzblock, and a sanctuary for graffiti artists. In “Antrieb,” by Lundberg, a mixed corps of dancers in cargo shorts, flanked by panels swirling with colorful graffiti art and young artists with cans in hand, marched forward and back over the gravel. They crawled under the panels and the audience followed, overwhelmed by the smell of spray paint, dust and crunching sounds of feet pounding on the gravel.

Music by the David Chowder Band, Rosin Murphy and Imogen Heap drove the movement. Dancers included: Michelle Buchanan, Eugenia Chen, Jacinto N. Delgado-Guizar, Amythyst Fritzler, Dana Lossing, Sarah Malena, Jennifer Peterson, Kiplinn Sagmiller, Rayna Stohl, Molly Terbovich, and Krysta Walsh, and they rolled around an old VW Bug. It too was covered in colors, and the regiment became one with the landscape, as if they’d always been there. While graffiti is often considered vandalism, this location and Lundberg’s choices invited the audience to see it as art and a way to promote ideas.

Next stop was the 47^th Street Stop with Isaac’s “Two Forms," as described in the introduction of this review. Then the tour group, including mothers with two baby strollers, boarded the trolley and rode west in air-conditioned comfort past neighborhoods, industrial parks and a giant cemetery to the 25^th and Commercial Stop.

Behind a chain-link fence stood ten dancers amidst giant slabs of concrete blocks. Their white long-tailed tuxedos blew in the wind, and with white sunglasses protecting their eyes, they peered up into the sun.

A hilarious bit of irony by Barnes, this ugly vacant lot soon became a football-sized stage. Dancers moved as geriatric Broadway stars, shuffling through big holes in the ground, all the while music by Paolo Conte blasted the lyrics “Life is wonderful.” Dancers Heather Dale, Jean Dugan, Jessica Curiel, Katie Griffin, Kelli Henderickson, Heather Horn, Pam Jong, Jacqui Lang, Alison Rose and Lara Segura, shook their fists at the sky, like stodgy old souls telling God they weren’t ready to leave the planet. With great snap, they chugged off into the distance with Barnes’ signature campy hunched-over shuffles, soft-shoe and Charleston, until they were one with the land. It felt more like watching a film than seeing a live event. A man passed by with a shopping cart filled with clanking recycled bottles, but was oblivious to their waving arms and the crowd waving back to them.

The final stop was at a vacant rec center, with choreography by Levy. Local dancers John Diaz, Bradley Lundberg, Daniel Marshall, Veronica Martin-Lamm, Erica Nordin, Jessica Reed de Cancel, Sadie Weinberg and guest Marcos Duran stood on square concrete slabs jutting up out of the corner. Some touched each other’s faces and others leaned on each other, but never pushed their partner off. Nordin and Weinberg climbed onto an overhang on the building and lay on their backs, circling their feet on the wall in giant arcs. Their comrades watched and a few mimicked circling movements on the ground, creating beautiful repetitions at different levels. Tribal rhythms from music by Mason Aeschbacher moved the group into a huddle, as if they’d finally become a community. But just as quickly, they scattered to the far edges of the space, as so many people in towns and cities across America often do.

Trolley Dances has become a San Diego tradition. About 2,000 people attended last year, and every year it just gets better. Bravo to the choreographers and the amazing dancers who torture their bodies in the hot sun eight times each day for two weekends. And hats off to the organizers who make it all happen. Trolley Dances is a mind-boggling production that brings new dance ideas into the community and entices people to visit areas of the city they’ve never seen. It's an adventure that arouses emotions and stimulates dialogue. It’s simply urban dance at its best.

Trolley Dances '06 runs Sept. 23 & 24 and Sept. 30 & Oct. 1. Guided tours begin at the Euclid Ave. trolley stop, 450 Euclid Ave., south of Market St. They leave every 45 minutes each day: 10 a.m., 10:45, 11:30, 12:15, 1:00, 1:45, 2:30, and 3:15 p.m.