At 7:42 a.m. on a bright Monday morning, a man exits the train and heads down the sidewalk, walking briskly to his office in downtown. Out in the suburbs, his wife drives to a dentist appointment while their son's school bus drops him off for another busy day in second grade, as the garbage truck lumbers down the street.

A typical family day in Chicagoland. And it's just another day in the Transportation Analysis Simulation System (TRANSIMS). Under a multiyear grant from the U.S. Department of Transportation, scientists at the Argonne National Laboratory's (TRACC) are using TRANSIMS to study easing traffic congestion in the Chicago metropolitan area, and to develop emergency evacuation scenarios for downtown Chicago.

TRANSIMS software was originally developed at the Los Alamos National Laboratory. TRACC researchers are using updated and enhanced versions of the program to create high-performance computer simulations that break the city's transportation system into millions of constituent parts.

To more easily view and understand those parts, TRACC researchers are collaborating with NCSA's Advanced Visualization Laboratory (AVL). TRACC modelers simulated an hour of time, sampling data at an interval of one second. To actually see how traffic might flow can provide new insights. For instance, TRACC researchers simulated traffic on a normal day and use that as a base to compare traffic flows in various simulated emergency situations.

The image shown here is taken from a movie created by AVL team member Alex Betts. It shows traffic movement in an area of Chicago's downtown over a simulated one-hour period of a normal day. The yellow ribbons represent traffic densities: wider is more dense, narrower is less. The arrows represent traffic signal activity. Each vehicle is assigned a unique color for easier tracking during animation.

And one never knows, the team may discover the solution to that most dreaded of city traffic conditions: gridlock.