Police plan to use what's called a long-range acoustic device to keep crowds from getting out of hand. ABC 7's Paul Meincke learned more about the device and what worked and didn't work in Pittsburgh.
The G20 Summit in Pittsburgh in September of 2009 has been called the most peaceful of modern day global summits. There are doubtless many reasons why arrests and property damage were minor compared to other host cities. Police say their intelligence paid dividends. Some protestors say the city purposely dragged out the permitting process for marches making it tougher to organize. And there is also Pittsburgh's layout: a compact downtown that come summit time was filled with riot-control police.
"My initial thought was there would be a lot of violence. A lot of security," said merchant Jimmy Sunseri.
There was indeed a lot of security. Pittsburgh has a police force of around 900 men and women, so for summit duty they recruited officers from other law enforcement agencies, including Chicago.
There were protest marches -- some with permits, some without. The largest was a march across a downtown bridge within sight and sound of the G20 meeting. The overriding message from the thousands involved was spend less on war and more on human needs.
There were no clashes, no arrests in that march, but there were other confrontations.
Pittsburgh used what's called a long-range acoustic device for loudspeaker dispersal orders, followed up by high-frequency, potentially painful audio chirps.
Pittsburgh's use of the LRAD was the first time that machine has been used in the U.S. for crowd control.
"I'm not gonna talk much about the LRAD because we are in litigation over it, but we did use it as a tool to get the message out," said Pittsburgh Public Safety Director Mike Huss.
There are still unresolved lawsuits over Pittsburgh's use of the LRAD and other arrests that protesters say took place without provocation. But the total number of arrests was less than 200, a mere fraction of what other G-summit cities have seen. And property damage was minimal.
From a policing standpoint, Pittsburgh has a couple things that work in its favor. It has hills and it has rivers.
Bridges near the convention center were closed. The immediate security perimeter and beyond were well fortified. The Strip District, just outside downtown, was the announced target of some demonstrators, but they never got close because the river is on one side and a wall of police was in the streets.
"One of the residents said it looked like Keystone Cops just preventing the people from coming. They kept shifting as needed," said Becky Rodgers, director of Neighbors in the Strip.
"I have to commend the police department in Pittsburgh that they did do a good job keeping us protected. We had no damage," said merchant Joe Hermanowski.
Chicago has done what every host city has done, which is to look at those cities that have previously held global summits and find best practices. But every city has its own unique challenges.
Chicago Police say they do have an LRAD available for use. It sends out live or recorded messages in a narrow sound beam. So you can hear the messages with clarity several hundred yards away. Police say that is how they intend to use it -- as a communications tool. But it is also equipped to emit those high-frequency alarm tones.