As the St. Louis Cardinals designed new Busch Stadium early in the 2000s, the September 11 attacks remained in their minds.
"Security was a major piece of our concern," said Joe Abernathy, vice president of stadium operations for the Cardinals and president of the board of directors for the Stadium Managers Association. "We had the benefit of the enhanced thinking on facility security that came up after 9/11. A lot of features we designed into the building make it more secure."
The ballpark, which opened in 2006, had five times as many security cameras as in early plans. Others measures added, such as a buffer zone around the ballpark to prevent a car from driving into the facility, reflect the security consciousness after the attacks.
Before 9/11, some emergency plans only had one step: call 911.
"There was recognition after 9/11 that stadiums were large potential soft targets," said Harold Hansen, director of life safety and security for the International Association of Venue Managers. "We had to take a serious look at safety and security."
Over the past decade, leagues prioritized security, funding increased and technology advanced. Cooperation between leagues and different agencies improved.
"If we work together, we're stronger than if we work separately," said Secretary of Homeland Security Janet Napolitano. "Folks in the sports industry have been willing and helpful participants in this notion of shared responsibility."
These actions changed the experience of going to a sporting event and stadiums are safer as a result. But 10 years after 9/11 officials are still determining how to best use the available resources.
A decade ago, stadium security was effective in day-to-day situations but unprepared for extreme cases like a terrorist attack. Security officials acted quickly in the immediate aftermath of 9/11, and many changes implemented have lasted: from banning coolers to increasing screening at the entrance. Although these procedures are now accepted as part of the gameday experience, some experts question how much they increase fan safety.
"It's security theater," says Mike German, policy counsel at ACLU's Washington legislative office. "It creates an impression that there's better security. Whether it does [increase security] ... hasn't been evaluated."
Assessing the usefulness of specific measures is a challenge because, although officials can see what screeners find, they don't know what was missed. And there's no way to know whether security deterred someone from attempting an attack.
After 9/11, researchers and stadium officials began examining their gameday procedures to figure out which actions were most effective.
"Our staff looked at what we do in our building," Abernathy said. "Leagues started taking a look collectively at what the standards should be."
Today, these lists of best practices form the base of stadium security. Many actions, such as forbidding re-entry, establishing no-fly zones during games and maintaining 24-hour live security at stadiums are now so well known that it seems impossible they weren't the norm. Adherence to these principles is enforced.
"We have ears and eyes at every event," said Dennis Cunningham, executive vice president of security for the NHL. "They report back after every game, and we'll reach out to find out why staffing levels dropped or if we notice other things out of the ordinary."
The National Center for Spectator Sport Safety & Security at the University of Southern Mississippi is one place where theories about best practices are tested. The center, started in 2006, studied the risk management cycle and determined that training and practice exercises were lacking. Since then, researchers have trained personnel and developed simulation exercises, including SportEvac, a computer-based modeling tool.
"We don't live in an ivory tower," the center's director, Dr. Lou Marciani, said. Representatives from all the major American professional sports leagues serve on the group's advisory board. "We know what's going on in each league and what issues we are facing," he said.
When advisory board members asked for a way to share more information with each other and learn about available resources, the center developed a national conference, the second of which was held last month in New Orleans. The opportunity to get experts together is valuable, but even before the convention began communication between different agencies, leagues and researchers had improved dramatically.
At the center of the information sharing is the Department of Homeland Security. Founded in 2003, DHS's office of infrastructure protection helps bridge the gap between the public and private sectors, providing evacuation planning guides, training courses and an outlet for different leagues to compare notes. The coordination, which requires cooperation of federal, state and local agencies, teams, stadium officials, private security and league offices, was much weaker a decade ago, officials say. Along with state groups and other federal agencies, like FEMA, DHS also offers research grants, and the office has conducted about 500 on-site assessments to help find vulnerabilities and offer suggestions for improvement.
When not among industry insiders, security officials are careful not to discuss specifics of building security. "Stadium managers are a pretty quiet bunch," Abernathy said, with a laugh. Other than the increased number of cameras, he declined to speak specifically about changes.
But experts and other officials talked generally about some of the technology used. Surveillance systems have advanced to the point some facilities are able to zero in on any seat in the stadium. Dirty bomb detectors are used at some major events, and one official acknowledged his facility takes air samples the day before the game as a baseline for measuring possible air contamination the next day. The next step in stadium security is the use of unmanned drones flying above the field, ready to enter in case of attack. These drones reportedly were used (and possibly debuted) at last year's Super Bowl in Dallas.
Experts agreed that new technology has greatly improved security, but they cautioned that determining which innovations are most appropriate for gameday settings is a challenge. Even when they can test the technology -- which helps to "separate snake oil salesmen from products with meaningful applications," Cunningham said -- balancing the desire to stay ahead of the curve with the costs and feasibility is difficult. It's one area officials see an opportunity for improvement.
Despite the invasiveness of this technology, fans seem to be accepting the security as a necessary nuisance. It's also likely they don't really know everything happening to keep them safe.
"For everything that the fans see, there's probably six or seven things behind the scenes that they don't see," said Ed Corey, senior game manager for the Rose Bowl.
Stadiums are now asking fans to be active participants in security. Campaigns like DHS's "If you see something, say something" compel them to take action. Many teams encourage fans to text or call a hotline to report bad or suspicious behavior.
It's just the latest step in the ramp up in security. Even though experts say stadiums are much safer, the looming threat pushes continued vigilance. Now that the risk is known, sites try to scope out potential threats, decrease vulnerability and minimize any consequences.
"We haven't sat still," Marciani said. "No one's sitting still."