Thousands of runners will race through Pittsburgh Sunday for the first Spirit of Pittsburgh Half Marathon, dashing across each of the city's three rivers on a 13.1-mile course that starts and ends at the South Side Works.

The event will close streets Downtown and on the North Side and South Side for several hours Sunday morning. Drivers should expect road blocks and delays starting at about 7 a.m. and easing as streets are re-opened on a rolling basis along the route. All streets will be open by 11 a.m.

Sponsored by MedExpress, a chain of medical clinics based in West Virginia, the race was organized by Run Wild Racing, a Columbus, Ohio company.

More than 3,200 runners from 34 states and four countries have registered for the race, said Doug Grout, Run Wild's owner and executive race director.

Among those thousands will be Meredith Colaizzi, Maureen Copeland and Andrew Althouse, all local runners.

Ms. Colaizzi, a 32-year-old Shaler resident who has run four marathons and three Iron Man triathlons, hopes to set a personal record Sunday.

The program coordinator of Magee-Womens Hospital's "Girls on the Run," a nonprofit that encourages healthy living for third- to eighth-grade girls, Ms. Colaizzi has "lost track" of how many half marathons she has run, she said, but she is still looking forward to the challenge.

"I like to sign up for races in order to force me to train and give me a goal," she said.

While Mr. Althouse, a 23-year-old Oakland resident and a University of Pittsburgh graduate student, can remember the number of half marathons he has run -- two -- he also hopes to set a personal record.

A former college football player, Mr. Althouse took up running to stay in shape, he said. He has set two goals for Sunday: He wants to run the course in 1 hour and 30 minutes, and he wants to win the "Cruiser" division, limited to male runners who weigh more than 200 pounds and female runners who weigh more than 150 pounds.

Maureen Copeland, a 27-year-old East Liberty resident who has run five marathons, is running the race to stay in shape between goals; she ran the Pittsburgh Marathon in May, and wants to run it again next year.

"This one's pretty much just for me," she said, "something to get back into the longer distances after some time off."

The course is relatively flat terrain for Pittsburgh, so Mr. Grout expects the race to be a fast one in which personal records are set, he said.

The race will cut off behind a 15-minute-mile pace marker; participants who fail to maintain that speed and fall behind for more than one mile will be pulled off the course, said Mr. Grout. The course can also be run as a two-person relay, though, with the first runner handing off the race after 6.55 miles.

For financial reasons, no prize money will be awarded.

Mr. Grout said he hopes the participants will race for "the spirit of racing" instead.

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