Years ago, the Escape from the Rock triathlon started a trend. The race, which begins at Luther Burbank Park, was the first to get the I-90 express lanes closed for a portion of the event.

“We were the first ones to get permission to use it,” said Dave Horning, the executive producer of Enviro-Sports, the company that produces the race. “All of the other events have followed us.” Now, several races throughout the year have gotten use of the bridge for participants.

This weekend, the race that started it all is back, starting at 8 a.m. on Sunday, Sept. 12, at Luther Burbank Park. The triathlon features a half-mile swim in Lake Washington, a 12-mile bike ride out and back on the closed I-90 floating bridge express lanes and then back for a 2.5 mile run.

“Jim Cullen, a Mercer Islander, inspired us to come out and put it on the first year,” said Horning. Cullen, who had participated in another Enviro-Sports race, the Alcatraz “Escape from the Rock” race in San Francisco thought a Mercer Island version would be fun.

“It’s been very successful,” said Horning. The race, which is capped at 800 participants, usually has anywhere from 600 to the full 800 Horning said, depending on the year.

“The City of Mercer Island and the Parks & Rec department have been very cooperative and helpful,” he said. The event benefits the Mercer Island High School aquatic and water polo clubs, helping provide funds to the also very successful programs.

The race groups are divided by age bracket, split in five year groups, said Horning. He said the youngest participant he remembers was 9-years-old and Horning said he wouldn’t want anyone much younger than that trying to do the race.

“It’s a unique event and it’s a challenge,” he said.

Due to the use of I-90 that morning, and for portions of the running race, several roads will be shut down. Roads will be closed from 8 and will reopen at approximately 10:30 a.m. The following streets will be closed: S.E. 24th between 81st Ave. S.E. and 84th Ave. S.E., 81st Ave. S.E. between 24th Ave. S.E. and N. Mercer Way, N. Mercer Way between 81st Ave. S.E. and 77th Ave. S.E. and 80th Ave. S.E. between N. Mercer Way and S.E. 27th Street. Traffic will be restricted to only local residents on the following streets: S.E. 26th Street between 84th Ave. S.E. and N. Mercer Way, 84th Ave. S.E. between S.E. 26th Street and S.E. 24th Street and N. Mercer Way between S.E. 26th Street and 81st Ave. S.E.

Anyone interested in participating can register online at envirosports.com, or can register at the last minute registration which will be held on Saturday, Sept. 11 from noon to 3 p.m. at the Community Center at Mercer View.

Visit Seattle Escape from the Rock for more information.