Evening Average Travel Time Index (General Purpose Lanes)​


The Travel Time Index (TTI) is the relationship between the travel time in the evening peak period (3 PM – 7 PM) and travel time during non-peak periods when traffic generally flows freely.  A TTI of 1.50 indicates that a 20-minute free-flow trip takes about 30 minutes or 50% longer during the peak period. The TTI is a way to understand how congestion impacts the travelers commute. The goal is to reduce congestion to a TTI of 1.3.  This would mean that a 30 minute trip during non-peak hours would take no more than about 40 minutes during the peak hour period. This measure tracks the TTI along the most congested freeways in the Metro-Atlanta region.

Strategic Objective

Optimize the throughput of people and goods on network assets throughout the day. GDOT has set a peak hour TTI of 1.3 along the Interstate General Purpose lane system.

Road to Improvement

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. HOT Lanes were implemented on the I-85 North corridor, as well as Flex Shoulder Lanes on GA 400. In addition, commute options, such as teleworking, carpooling, vanpooling, and transit can help relieve congestion.​

Disclaimer: The Georgia Department of Transportation makes no representation or warranties, implied or expressed, concerning the accuracy, completeness, reliability, or suitability for any particular purpose of this information and data contained on this website.