Central Puget Sound Interstate 90 - Severe congestion
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Measures of severe congestion on I-90 in the central Puget Sound region
Severe congestion
Severe congestion occurs when highway travel speeds are slower than 60% of the posted speed (about 36 mph for a 60 mph speed limit) leading to reduced highway efficiency. Refer to WSDOT's Handbook for Corridor Capacity Evaluation (PDF 5.9MB)
Sources: WSDOT Transportation Safety and Systems Analysis Division and WSDOT TRACFLOW (https://tracflow.wsdot.wa.gov/)
Performance highlights
In 2023, commuters driving on I-90 between Bellevue and Seattle experienced severe congestion with speeds of 36 mph or less:
- At 8:35 a.m., travelers experienced severe congestion on 52.8% of weekdays in 2023 an increase from 23.3% in 2022
- At 5:20 p.m., travelers experienced severe congestion on 80.6% of weekdays an increase from 53.0% in 2022.
Likewise travelers experienced severe congestion between Seattle to Bellevue:
- At 5:10 p.m., travelers experienced severe congestion on 9.9% of weekdays an increase from 3.8% in 2022.
In 2022, severe congestion in commute routes increased compared to 2021 due to the ongoing recovery of traffic volume in the wake of COVID-19. However, severe congestion in 2022 was still lower compared to the pre-pandemic level. Commuters taking I-90 between Bellevue and Seattle drove more often in severely congested conditions (36 mph or less) than in 2021. For example, during the peak morning commute from Bellevue to Seattle, 23.3% of days saw speeds below 36 mph at 8:35 am in 2022 compared to 4.0% in 2021. The peak evening commute was slightly worse in 2022, with 56.6% of days experiencing speeds below 36 mph at 3:40 pm as opposed to 50.8% in 2021.
In 2021, severe congestion in some commute routes increased compared to 2020 due to recover of traffic volume in the wake of COVID-19, but was still lower compared to the pre-pandemic level. Commuters taking I-90 between Bellevue and Seattle drove in severely congested conditions (36 mph or less) saw mixed result in 2021 compare to 2020. For example, during the peak morning commute from Bellevue to Seattle, 1-4% of days saw speeds below 36 mph in 2021 compared 4-14% in 2020. The peak evening commute in 2021, was up with 30-51% of days experiencing speeds below 36 mph as opposed to 12-23% in 2020.
In 2020, due to the statewide response to COVID-19 there was significant decrease in severe congestion compared to the previous year. Commuters driving between Bellevue and Seattle via I-90 drove in severely congested conditions (36 mph or less) less often than in 2019. For example, during the peak morning commute from Bellevue to Seattle, the percent of days with speeds below 36 mph was between 4-14% in 2020 as opposed to being between 63-76% in 2019. The peak evening commute in 2020, with the percent of days with speeds below 36 mph between 12-23% as opposed to between 90-92% in 2019.
In 2019, commuters driving between Bellevue and Seattle via I-90 drove in severely congested conditions (36 mph or less) less often than in 2018. For example, during the peak morning commute from Bellevue to Seattle, the percent of days with speeds below 36 mph was between 63-76% in 2019 as opposed to being between 81-85% in 2018. The peak evening commute was slightly worse in 2019, with the percent of days with speeds below 36 mph between 90-92% as opposed to between 87-89% in 2018.