A Rare Chance to Stroll a Park Avenue Tunnel, in the Name of Art On Saturday, the city will temporarily shut the Park Avenue tunnel to car traffic, and the 1,394-foot cavern - which runs on Park Avenue between 33rd and 40th Streets - will be turned into an incandescent, echoing, interactive art show. Since the 1930s, the Park Avenue tunnel has been closed to pedestrians, and its weathered stone walls and ridged metal ceiling have been visible only to New Yorkers whipping past inside their automobiles. That will soon change, to dramatic effect. On Saturday, the city will temporarily shut the tunnel to car traffic, and the 1,394-foot cavern - which runs on Park Avenue between 33rd and 40th Streets - will be turned into an incandescent, echoing, interactive art show. From 7 a.m. to 1 p.m., visitors will be able to enter the tunnel at 33rd Street, at the spot where Park Avenue dips sharply downward. (There are six signs there that tell pedestrians to stay away. Ignore them.) Participants will be instructed to walk to a midpoint in the tunnel and deliver short messages into a silver intercom. The messages will then billow outward in waves of sound and arching light until they disappear. The intensity of each beam will be determined by the pitch and volume of the messenger's voice. And the messages will shoot out quickly, one after another, creating a seemingly endless, ever-changing cascade of sound and light. "What makes the experience valuable is the fact that it's ephemeral," said the installation's creator, Rafael Lozano-Hemmer, 45. The project "allows us to remember that we are on earth for a very brief period of time, and then we're going to die. And it helps us live perhaps more intensely. We're more alert to the fact that it ends, that we're getting recycled, that there is a flow. The show will be staged on three consecutive Saturdays, the last on Aug. 17. A team of about 30 will build it each Friday evening, working through the night, only to take the entire setup down on Saturday. When the tunnel reopens to traffic sometime before 5 p.m., drivers will see no evidence of the light show. Mr. Lozano-Hemmer has been creating large-scale interactive art for more than 20 years, and most of his installations mix architecture and performance in an effort to highlight the simultaneously seductive and predatory qualities of technology. He often explores the way individuals are willingly, and unwillingly, complicit in creating expanding cultures of surveillance. "Pulse Park," in Madison Square Park, consisted of a series of light beams that swept across the park's center field. Their intensity was regulated by a sensor that measured the heart rate of visitors. "Open Air," in Philadelphia, lighted up the city's sky by asking participants to record messages via a Web site or a phone. The messages were played back in strobes whose brightness and position were regulated by the voices" frequency, volume and GPS location. "I'm passionate about defending the eccentricity of these projects that all of a sudden are alien," Mr. Lozano-Hemmer said. They're strange. They're weird. And they make people have an opportunity to spend time in public space. Mr. Lozano-Hemmer was born in Mexico, grew up in Spain and now lives in Canada. He has three passports. He is a bespectacled and curly-haired father of three. During a test run inside the tunnel on Saturday, he moved up and down the cool, darkened space, conferring with his tech team. "We're going to have a small army in here," explained Erik Perry, the senior project manager at WorldStage, a production company that is working with the artist. It's a lot to do. This is just 30 lights. It will be 300 when we're done. The voice tunnel is part of a larger New York City event series, called Summer Streets, during which the Transportation Department hosts activities along the nearly seven-mile route from the Brooklyn Bridge to Central Park. For an artist who prides himself on providing a platform for free speech, working in New York has been difficult, Mr. Lozano-Hemmer said. The Police Department originally asked him to employ a six-second delay on all messages reverberating through the tunnel. He balked. "In authoritarian regimes, that can work," he said. But not here. This is the place for people to express their views. That's what this project is about. And if you want to censor it - I've never in my life censored a work, and I won't do it. The two parties compromised. A person will monitor the messages as they are spoken. All speech, controversial or not, will be permitted, except anything that could create immense alarm, like someone screaming "Fire!" "We have a little delete button," Mr. Lozano-Hemmer said. Hopefully we don't have to use that.