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MAG is tracking the amount of time commuters are stuck in traffic on a daily basis. The measure of congestion delay is calculated from speed data, which covers all major freeways and most of the arterial streets in Maricopa County.

Transportation, COVID-19, Traffic

Updated: February 7, 2024

The Maricopa Association of Governments is tracking the amount of time commuters are stuck in traffic on a daily basis. The measure of congestion delay* is calculated from speed data, which covers all major freeways and most of the arterial streets in Maricopa County on a daily basis, 24 hours a day. Please note that the graphs below are derived from INRIX data, which are proprietary and require attribution. A single notation within a report that contains INRIX data and a single logo on web pages that draw from INRIX data is acceptable. For example, a reporter could say "according to travel time data by the analytics company INRIX." The graphs below incorporate the appropriate attributions.

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*The delay (measured in vehicle hours) is calculated as the excessive travel time for all vehicles when average speed during a given hour is at least 20mph lower than the free-flow speed. The daily delay is calculated as the sum of hourly delay per day in the region.

What does this chart tell me?

  • Fewer cars means less congestion, which means high average speeds.
  • Speeds on freeways did not change noticeably from the 3rd week of March to the end of August in 2020, and then began to decrease due to the increase of congestion.
  • Data for this chart are updated quarterly.

 

What does this graphic show?

  • Less traffic congestion means faster travel times; faster travel times mean less delay when compared to free flow traffic.
  • MAG monitors speed data for all major freeways and highways in Maricopa County 24/7. Congestion delay compares actual travel times, such as rush hour travel, to travel times when traffic is free flowing.
  • Since falling in mid-March 2020, congestion delays remained relatively low and stable through the fourth week of August 2020. Congestion delays started to gradually increase beginning in September 2020, while still remaining lower than pre-pandemic conditions. By end of March 2023, we were back to pre-pandemic congestion delay.
  • Read more about how traffic has changed during COVID-19 here

 

What does this graphic show?

  • Average Weekday Daily Traffic Volume for the week of March 2, 2020, is considered "normal" traffic conditions, defined as 100%.
  • The lowest number of vehicles on the regional roads is observed during the 2nd week of April 2020, as 63% to traffic volumes under normal conditions.
  • Since hitting its lowest volumes of 63% of normal in the second week of April 2020, the number of vehicles on regional roads increased to 87% of normal traffic volumes during the third week of June. Volumes decreased to below 80% during July 2020, and gradually recovered to normal conditions after March 2021.

NOTE: The data are primarily for the freeways and arterials in Maricopa County.

What does this chart show?

  • The week of March 2, 2020, is considered "normal" traffic conditions, defined as 100%.
  • After heavy truck volumes showed a comparatively modest drop to the 91% of normal volumes during the 2nd week of April in 2020, heavy truck volumes have maintained at or above 100% since May of 2020.

NOTE: The data are primarily for the freeways and state highways in Maricopa County.

What do these satellite photos show?

 

Nitrogen dioxide (NO2) emissions are emitted into the air when fuel is burned in cars, trucks and buses, power plants, off-road equipment, manufacturing facilities, and wildfires. With the reduction in traffic due to the pandemic, we'd intuitively expect to see a matching reduction in the measurement of these emissions. However, satellite data comparing NO2 emissions over the MAG region in 2019 and 2020 indicates the story is much more complex. The amount of NO2 emissions in the air is impacted by a variety of factors, including weather and the transport of emissions from other countries and areas in the U.S. These charts show both increases and decreases in NO2 emissions during the months since the virus began.

  • Comparing the same period of March 16 to April 21, 2019 to March 16 to April 21 2020, findings show a reduction of 16.95% in these emissions.
  • Comparing the same period of April 22 to June 7, 2019 to April 22 to June 7, 2020, findings show an increase of 11.44% in these emissions.
  • Comparing the same period of June 8 to July 24, 2019 to June 8 to July 24, 2020, findings show a decrease of 10.27% in these emissions.
  • Comparing the same period of July 25 to November 12, 2019 to July 25 to November 12, 2020, finding show a decreased by 2.71% in these emissions.

What do these charts show?

  • Active transportation trips (biking, walking and running) have increased significantly since March 2020.

Updated February 7, 2024

Published August 31, 2020