Central Puget Sound High Occupancy Vehicle - Reliability
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Measures of HOV network speed and reliability in the central Puget Sound region.
HOV reliability
The speed and reliability performance standard for freeway HOV lanes was adopted by WSDOT and the Puget Sound Regional Council in 1991. The standard states that travelers in the HOV lane should be able to maintain an average speed of at least 45 mph 90% of the time during the peak hour of travel. For details on the methodology used to calculate HOV Reliability, see WSDOT's Handbook for Corridor Capacity Evaluation (PDF 5.9 MB). Even when performance is reduced during congested periods, HOV lanes still generally provide speed and reliability benefits over adjacent GP lanes. During the off-peak times of day, all HOV corridors generally meet the standard.
I-405 ETL/SR 167 HOT Performance: I-405 ETL commutes between Lynnwood and Bellevue are not reported in this section, as they have separate legislatively mandated speed and reliability performance measures and reporting requirements (per RCW47.56.880). For consistency, WSDOT follows the same reporting guidelines for the SR 167 HOT lanes. For the most up-to-date performance information on the I-405 ETLs and the SR 167 HOT lanes, see WSDOT's Toll Division Annual Reports at www.wsdot.wa.gov/tolling/publications.htm.
Sources: WSDOT Transportation Safety and Systems Analysis Division and WSDOT TRACFLOW (https://tracflow.wsdot.wa.gov/)
Multi-year trends
In 2021 and 2022, the reliable performances deteriorated compared to 2020, despite the ongoing recovery of traffic volume in the wake of COVID-19.
In 2020, due to the statewide response to COVID-19 many commute routes increased reliability performance compared to previous years.
From 2018 through 2019, HOV speed and reliability performance declined at most locations before improving in 2018 and holding relatively steady in 2019. This trend is consistent with the trends observed in PMT and person throughput over the same period. Of the 10 commute corridors for which speed and reliability metrics are reported, both morning and evening commute of I-90 usually meet the HOV speed and reliability standard every year from 2017 through 2021.
Annual highlights
In 2022, six of the 10 HOV commute routes monitored did not meet the HOV standard for speed and reliability performance. This is a decrease compared to five corridors in 2021. The six corridors that did not meet the speed and reliability standards were: the morning and evening NB and SB I-5 commute between Seattle and Everett, the morning and evening NB and SB I-5 commute between Seattle and Federal Way, and the morning and evening NB and SB I-405 commute between Bellevue and Tukwila. Amongst these six corridors, I-405 Bellevue to Tukwila in the southbound during the evening commute scored relatively low (14%) compared to 34% in 2021.
In 2021, five of the 10 HOV commute routes monitored met the HOV standard for speed and reliability performance. This is an increase compared to three corridors in 2020. The five corridors that met the speed and reliability standards were: the evening SR 520 eastbound commute from Bellevue to Redmond, I-90 eastbound commute Seattle to Issaquah, morning I-5 southbound commute from Everett to Seattle, I-90 westbound commute from Issaquah to Seattle, and I-405 northbound commute from Tukwila to Bellevue. Amongst these five corridors, I-405 Bellevue to Tukwila in the southbound during the evening commute scored relatively low compared to 2020.
In 2020, due to the statewide response to COVID-19 many commute routes increased reliability performance compared to the previous year. Three of the 10 HOV commutes monitored met the HOV standard in 2020 for speed and reliability performance, up from one corridor in 2019. The three corridors that met the speed and reliability standard in 2020 were the evening SR 520 eastbound commute from Bellevue to Redmond, the morning I-90 westbound commute from Issaquah to Seattle, and SR 520 westbound commute from Redmond to Bellevue. Other commutes got relatively high scores compared to previous years ranging between 77% and 89%.
In 2019, one of the 10 HOV commutes monitored met the HOV standard for speed and reliability performance, down from two corridors in 2018. The one corridor that met the speed and reliability standard in 2019 was the evening I-90 eastbound commute from Seattle to Issaquah.
In 2018, two of the 10 HOV commutes monitored met the HOV standard for speed and reliability performance, an improvement from one corridor meeting this standard in 2017. The two corridors that met the standard in 2018 were I-90 Issaquah to Seattle WB in the morning and I-90 Seattle to Issaquah EB in the evening.