Weekly Viz 2025-07-07

Travel Time Index

The Travel Time Index is a metric published by the Home. It is the ratio of the travel time during the peak period to the time required to make the same trip at free-flow speeds. A value of 1.3, for example, indicates a 20-minute free-flow trip requires 26 minutes during the peak period. This week, I am visualizing the trend of Travel Time Index in major US urban areas.

My Visualization

This visualization is a line chart – there are four highlighted lines, representing the average travel time index of very large/large/medium/small urban areas. The other lines are the US urban areas.

Please notice that all the visualizations are designed for desktop view, so it is recommended to view them on a desktop device.

Dashboard link

Insights

• From 1982 to 2019, the Travel Time Index has consistently increased across all urban area sizes, indicating worsening traffic congestion over the decades;
• The Travel Time Index shows a positive correlation with the size of the urban areas – the Travel Time Index of a very large urban area reached 1.35 in 2020, while the Travel Time Index of small urban area is only 1.07 in 2020;
• There is a sharp drop in Travel Time Index around 2020 across all city sizes due to the pandemic lockdowns, but it bounced back quickly after 2022.

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