What is Snarling Up I-85? GDOT Study Provides Some Answers

If you have been following my blog, you know that I am a lawyer who represents people injured in car wrecks, and I like to keep up with the information about the crashes that occur in and around Georgia. I recently read an interesting GDOT study that looked at the incidents and car accidents along I-85 in DeKalb and Gwinnett Counties. This study was especially important because it looked at some exits where traffic and auto accidents have been so bad that the Georgia Department of Transportation (“GDOT”) has installed HOV lanes.

The study was done because GDOT converted a stretch of HOV lane into a pay lane, or “HOT” lane, in October 2011. (HOT stands for “High Occupancy Toll.”) GDOT hired Jacobs Engineering Group to determine how GDOT could go about studying the effect that the conversion was having on congestion, auto wrecks and other incidents.

On February 26, 2012, Jacobs Engineering reported back to GDOT about how a comparison might be done. In the course of the study, the firm looked at incidents that occurred in 2010, and it found some interesting facts.

(1) The engineering firm looked at a total of 2944 incidents. It was not just looking at motor vehicle accidents – it was looking for any incident on that stretch of highway, which could include debris in the road, a stalled vehicle on the side of the road, etc. In fact, only 18% of the incidents along that stretch of I-85 were car accidents. Construction caused 13% of the incidents. Debris caused 7% and roadkill caused less than 1%. Another 1% of the time roads were closed due to “other”, and in less than 1% the incident was due to “other closure.” A whopping 60% of the incidents related to stalled cars.

(2) First, a full 1/3 of the accidents (33%) occurred during the weekday peak hours – even though the peak hours make up only 7% of the hours that occur in a week. The reason is obvious to anyone who has driven in Atlanta traffic during rush hour.

(3) While 48% of the incidents did block at least one lane along I-85, the majority of incidents did not block any lanes at all. Of course, a car wreck would nearly always block at least one lane of traffic, at least until the drivers could get their vehicles to the side of the road.

(4) An extremely small 2% of the incidents blocked an HOV lane. In all, 973 incidents occurred during the peak rush hours. 485 of these incidents blocked an HOV lane. Only 21 of the 973 incidents blocked the HOV lane.

(5) Once a lane got blocked, the wait time to get the lane cleared was substantial. The study eliminated blockages caused by construction, and even so found that on average a lane remained blocked for 27 minutes. The HOV lane may have been blocked less often, but when it was blocked it did not fair much better than the other lanes, since it took on average 25 minutes to clear the block.

(6) When 1 lane was stopped, generally more than one lane was stopped. On average, 1.4 lanes wound up being stopped per incident.

(7) More incidents occurred in the summer (29%) and fall (28%) than in the winter (23%) and spring (20%). (As an aside, I could not figure out why the incidents split this way. I can figure that more people who are unfamiliar with our roadways might be headed down I-85 for summer vacations, but that would not explain why fall saw so many more incidents than spring did.)

(8) The car accident and other non-crash incidents spread across the days of the week in just the way you might imagine. Most incidents clustered on the weekdays, and a smaller percentage happened on weekend days. Monday had 16% of the incidents and Tuesday had 17%. The incidents peaked on Wednesday, which had 19%. 18% of the incidents occurred on Thursday and a relatively smaller 15% happened on Friday. The rate dropped by about half on the weekends: only 8% of the incidents occurred on a Saturday and 7% on a Sunday.