Runners cross the P.R. Olgiati Bridge on Sunday, Oct. 15, 2017, during the Seven Bridges Marathon. A miscalculation left the race 0.63-miles too long. The Four Bridges Half Marathon was 0.63-miles too short, according to three race officials.

For the third time in as many years, a local marathon or half marathon has been miscalculated.

Both the 7 Bridges Marathon and 4 Bridges Half Marathon held Sunday were incorrectly measured, leaving the full marathon 0.63 miles too long and the half marathon 0.63 miles short.

"We own it. [Course certifier Brandon Wilson] owns it, and we know how hard people work, and we want to be completely transparent," race director Jay Nevans said. "... In both cases we feel terrible."

The 2015 4 Bridges Half Marathon was also miscalculated, as was the Chattanooga Marathon in 2016.

After the 2015 error, the 7 Bridges Marathon and 4 Bridges Half Marathon brought in an outside course certifier to make sure the course was correct. Sunday's miscalculation was made during the certification process.

Wilson has certified hundreds of courses.

"This is, as far as we know, the only error he has ever made," Nevans said.

Times for the full marathon, which is a qualifier for the Boston Marathon, will be adjusted. Race officials averaged paces for the race down to 26.2 miles. As with most half marathons, 4 Bridges is not a qualifier for any other race.

Nevans apologized for the error and said organizers are doing what they can to make it right.

Nathan Pierce, 31, of Huntsville, crosses the finish line first in the Seven Bridges Marathon Sunday morning. A miscalculation left the race 0.63-miles too long, according to three race officials. The Four Bridges Half Marathon was 0.63-miles too short.

"Every year, we make changes to the course, mainly for safety reasons," he said. "It was decided last year to take River Street and Coolidge Park out of the start ... so when the certifier made those adjustments, he just made an error calculating both races."

Most half marathoners and the fastest marathon runners had already finished by the time the mistake was identified and corrected. However, Irene Sewell was still on the course, in her high heels, attempting a world record.

Race officials corrected the finish while she was on the course to make sure she was not disqualified, and by about 4:30 p.m., Sewell posted on Facebook that she achieved her record.

"Well world, I DID IT," she wrote in a public post. "I'm still in shock, but it really happened. I ran a marathon today in high heels and set a Guinness World Record with two minutes to spare!"

Sewell could not be reached for comment Sunday night.

Women's full marathon winner Jackie Merritt found out while on the course that something was wrong.

She was in the lead most of the race, meaning a race official rode on a bike alongside her.

"The guy who was on the bike, I think it was at the 15 mile marker, said, 'Well, that's not right,'" she said. "I was thinking it would correct itself."

It never did, and Merritt and others ran the extra distance. However, Merritt was using the race to prepare for other races, so she wasn't worried about the extra distance and was complimentary of the race as a whole.

"They had great support. I know they might have had issues marking it in the past, but I never had an issue knowing where to go," she said. "That was very clear. It was well marked. The mile was just off, which sucks when you're like 'I don't know if I have two miles to go or one mile to go but I feel like I'm dying.'

"Ultimately, I can't complain too much, it was just a training race for me," she said.

For those hoping to qualify for Boston, the time for the extra distance has been removed, Nevans said.

Contact staff writer Mark Pace at mpace@timesfreepress.com or 423-757-6659. Follow him on Twitter @themarkpace and on Facebook at ChattanoogaOutdoorsTFP.

Contact staff writer Rosana Hughes at rhughes@timesfreepress.com or 423-757-6327. Follow her on Twitter @HughesRosana.

Results Full Marathon Women 1. Jackie Merritt 2. Meghan Ogle 3. Kyra Fowler Men 1. Nathan Pierce 2. Daniel McGinley 3. Richard Reinhardt Half Marathon Women 1. Sara Gibson 2. Emily Cooper 3. Daphne Kirkwood Men 1. Christian Thompson 2. Josh Whitehead 3. Chris Jackson

This story was updated Oct. 15 at 2:45 and 11:59 p.m. with additional information.