ROCKFORD - (WIFR) "As traffic investigators we are DUI investigators for the most part. We investigate other traffic accidents, traffic violations. But with DUIs we work that particular time of the night where you're going to have perhaps the majority of intoxicated or impaired drivers on the street," said Investigator Vernon Sims.

In a recent study from the Alliance Against Intoxicated Motorists, Rockford is ranked number one in Illinois, outside of Chicago, for DUI arrests in 2009. Four Rockford officers are in the top 20 for arrests. Investigator Vernon Sims caught 113 drunk drivers last year.

"The main thing we are looking for, we're looking for impaired driving. People that are crossing the center line, people that are driving too close to the curb. People that are driving recklessly in some manner. Perhaps someone who's driving excessively fast or perhaps someone who's driving exceptionally slow," Sims said.

Sims says he usually catches drunk drivers between 11 p.m. and three in the morning, especially on the weekends. Sunday night between nine and two is a prime time as well.

"When I'm on patrol I usually go with the main arterial streets, focus one who's where there's high traffic from bars. Restaurants that serve alcohol. Driving in those areas looking for cars that are driving in the manner I described earlier," Sims said.

When he pulls someone over it's his goal to find out why someone is driving erratically. Sometimes it's just because the person is texting or drowsy, but most of the time the offender is given away by the tell tale smell of alcohol.

"Some folks are just like any other folks we come in contact with, some are very remorseful, very sorry the did it. Some of the people we are arresting for being impaired are not necessarily violent, but they just tend to be very belligerent be very talkative and they tend to blame everyone except for themselves," Sims said.

A disturbing trend was found in the study; 83 percent of all drivers arrested for DUI are first time offenders. These drivers could potentially be more dangerous, as investigator Sims says he does notice first timers drive more erratically than a someone with a history of driving drunk.

The study also paints a picture of who the average drunk driver in Illinois is. They are a male, under the age of 35, with a blood alchoal content of .16 , that's twice the legal limit.