The annual report on congested roads by the Texas Department of Transportation (TxDOT) lists only one roadway segment in Collin County among the top 100, according to 2024 data analyzed by the Texas A&M Transportation Institute (TTI). A short segment of U.S. Highway 75 in Plano, from Legacy Drive to the President George Bush Turnpike, ranked No. 30 on the most-congested list. Several other roadway segments in the county ranked outside the top 100, but conditions worsen the closer drivers get to Dallas.

The rankings were based on time lost in traffic compared with what a trip would take under free-flow conditions. TTI researchers calculated “delay per mile,” which measures how many total hours drivers spend moving slower than the normal uncongested speed across each mile of roadway over an entire year. So, the higher the delay-per-mile figure, the worse the congestion.

Researchers also computed a Texas Congestion Index, or TCI, representing the ratio between actual rush-hour travel time and free-flow travel time. A third measure, the Planning Time Index, or PTI, estimated the worst day of the month by calculating how long a traveler might need to reliably arrive on time.

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