By Derrick Blakley

(CBS) — In the wake of Hurricane Harvey and now Irma, Chicagoans may be wondering: Could we evacuate during a catastrophe, and how?

CBS 2 Political Reporter Derrick Blakley has more.

State, county and city officials are constantly revising plans to empty out Chicago in the event of a disaster.

But emptying the nation’s third largest city – with 2.7 million people — presents significant challenges.

“There will always be challenges whenever you try to evacuate large scale populations,” says Alicia Tate-Nadeau, executive director of the Office of Emergency Management and Communications.

One of Chicago’s biggest hurdles: the sheer volume of traffic. Some 660,000 people would need to get out immediately. Local expressways could only handle 180,000 cars in three hours.

“We actually experienced that during 9-11, where there was a self-evacuation of people from the central business district,” Tate-Nadeau says.

What helped on 9-11 is what planners would rely on today, using both Metra and the CTA to move people out of the central city. Chicago’s plan dates back to the Daley, but it’s constantly being updated.

FEMA authorities met in Springfield Thursday to study catastrophes and evacuation.

“Evacuating any city of this size is an extremely complicated and difficult process, and we saw that in Houston,” Cook County President Toni Preckwinkle said.

In the face of hHarvey, Houston’s mayor feared ordering evacuations would trigger chaos.

But now, with Irma bearing down on South Florida, officials are telling residents to get out.

Chicago’s OEMC boss says they’re currently in the process of re-evaluating Chicago’s evacuation plan, incorporating new resources, including cell phones.

A new system called the Integrated Public Alert System can distribute localized information by text during an emergency.