Evanston runner John Schroeder had just finished the Boston Marathon when he heard what sounded like pieces of construction equipment falling off a building. Yet he didn't believe it when someone said the race course had been bombed.

Who, he thought, would bomb a marathon?

That sense of disbelief vanished forever in the smoke and chaos of Boylston Street. But as the Chicago Marathon approaches, many local athletes who were in Boston say they will be in Grant Park onOct. 13, ready to run and undeterred by the violence of April.

"I thought it was such a fluke, so unlikely to occur (again)," said Schroeder, 50. "Those guys, if they want anything, want people to be afraid. So I would say, 'Screw them.' Just go and trust that nothing bad will happen."

Such confidence appears widespread among runners, a reflection of their unwillingness to cave in to fear and their faith in new security arrangements designed to protect athletes and spectators in Chicago's first post-bombing marathon. Local runners, including some who were in Boston when its course was attacked, believe the resolve and resilience they learned from their sport will allow them to conquer not only the 26-mile race but also their own apprehensions.

And those who are in charge of ensuring that nothing bad happens say they're taking every precaution. Marathon officials are for the first time requiring runners to carry belongings in clear plastic bags and pick up their race packets in person. Spectators who want to meet runners in a reunion area after the race must submit to a bag search.

"The cornerstone of what we do is participant safety," said marathon director Carey Pinkowski. "I feel very confident that our comprehensive security plan will continue to provide a safe and memorable atmosphere."

Along the course, police plan to deploy bomb-sniffing dogs, subject spectators to random bag checks and make use of the city's network of more than 20,000 security cameras, many of which will be monitored live by police officers, said Deputy Chief Steve Georgas of the Chicago Police Department's Bureau of Patrol.

Federal agencies such as the Secret Service and the FBI are also involved in marathon security, which Georgas said is standard for large-scale events. The federal shutdown, should it continue through race day, will not affect those plans, FBI spokeswoman Joan Hyde said, "because our mission is protecting life and property and addressing matters involving national security."

Some have criticized federal law enforcement officials for failing to share intelligence with Boston police before the marathon bombing about the Tsarnaev brothers, who were later identified by authorities as the bombers. Georgas said Chicago has an "excellent" relationship with federal agencies, bolstered during such recent events as the NATO summit and the Blackhawks' championship parade.

"We're doing everything we possibly can," he said.

Marathon officials said they were not aware of any runners among the 45,000 entrants — most of whom registered in February, before the Boston bombings — who planned to stay away because of safety concerns. The number of charity runners, who registered after the bombings, is actually up slightly from 2012.

Even so, some local runners who witnessed the bombing said they felt a bit nervous going into Chicago's race. Susan Balthazor said she was close enough to the first bomb to be knocked sideways by the blast, and that the experience shook her badly. But she found comfort in conversations with her pastor and other runners, and when asked to help guide a blind runner through the Chicago Marathon, she said yes.

"It's probably good to have my mind worried about her (rather) than just me, me, me," Balthazor, 47, of Waukegan, said. "I can worry about something other than the race and if something's going to happen."

Mark Buciak, a Chicago running coach who competed in Boston, has detected no sign of fear among the 200 athletes he is preparing for the race.

His advice to them, he said, is this: "Your job or objective is to run your race and let the marathon (staff) and security forces do their job. Of course, you have an eye open for something, but to let it ruin your day, that means you're letting evil win."

Kielo Sauvala shares that attitude. She said she was approaching Boston's finish line when the bombs went off, and was struck in the leg by some of the ball bearings that had been packed inside the explosives. (She was not seriously hurt.)

It was a terrifying experience, she said, but she decided almost immediately to continue running in major marathons.

"You can't control what other people are doing, but you can't give up what you want to do," said Sauvala, 56, of Glenview. "There are always crazy people around us. We have to accept that."

Jeff Cramer, head of the Chicago office for the private security company Kroll, said sprawling marathon courses are more difficult to protect than events that take place in a controlled setting. While authorities are taking sensible precautions, he said, it's impossible to eliminate all possible danger.

"Is there a higher risk with this type of event?" he said. "Realistically, you'd have to say this poses more of a challenge for law enforcement."

Volunteers along the course have been instructed to be vigilant. David Reithoffer, who has worked an aid station in Lakeview for more than 20 years, said volunteers there are trying to help police by keeping their bags stowed in a central location.

"We're trying to avoid the issue of having that one backpack sitting all by itself on the sidewalk," he said.

Andre Bennatan, 54, of Lake Forest, said he had no issues with the marathon's new security rules. He witnessed the Boston bombings from a restaurant near the finish line — he had finished the race about an hour earlier — and said the fear of the first few moments was quickly replaced by determination to keep running high-profile events like the Chicago Marathon.

"Maybe running marathons, it trains you to be resilient," he said. "To go out whether it's cold or not, whether you're hurting or not. Maybe, in the face of adversity, you're more inclined to say, 'OK, that's not going to stop me.'"

Tribune reporter Jeremy Gorner contributed.

jkeilman@tribune.com

Twitter @JohnKeilman