Congestion in Metro-Atlanta causes travelers to anticipate delays and allow for additional time when traveling during peak morning hours (6 AM – 10 AM). The goal is to reduce congestion such that a 30 minute trip during non-peak traveling hours would take no more than about 40 minutes during peak hours. Likewise, a speed of 55 mph during non-peak hours would be reduced to about 40 mph during peak hours. This measure tracks average speeds across the most congested freeways in the Metro-Atlanta region. By focusing on these key roadways, GDOT can identify and address the biggest challenges to congestion in our region.
Optimize the throughput of people and goods on network assets throughout the day. GDOT has set a peak hour target of 40 mph or better for the Interstate General Purpose (GP) lane system.
Road to Improvement
GDOT fell short of its 2016 target, achieving an average peak hour speed of 36.1 miles per hour. Addressing the issue of congestion within the Atlanta region is a challenge that requires time and resources. GDOT is exploring several options to improve congestion and provide choices. Managed Lanes, implemented on the I-85 North corridor are being extended further north. Managed lanes are also under construction on the I-75 North and South corridors. Flex Shoulder Lanes on GA 400 and variable speed limits for portions of I-285 have been implemented. Also, the State Legislature has passed the Transportation Funding Act, which will provide additional resources needed to move projects forward to address congestion. In addition, commute options, such as teleworking; carpooling; vanpooling, and transit can help relieve congestion.
Travel Time Index
Another way to evaluate the effect of congestion on the time spent commuting is the Travel Time Index (TTI). The TTI is the relationship of travel time in the peak period to travel time at free-flow conditions. A Travel Time Index of 1.30 indicates a 20-minute free-flow trip takes 26 minutes or 30% longer in the peak period.
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