Central Puget Sound High Occupancy Vehicle - Person throughput
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Measure of person throughput on the HOV network in the central Puget Sound region.
Person throughput
Person throughput is the number of people who pass a specific point in a defined timeframe and is a key metric in determining HOV lane performance. In order to calculate HOV person throughput, WSDOT estimates the number of vehicles and travelers at 10 locations on the major freeway corridors in the central Puget Sound region.
For details on the methodology used to calculate HOV lane performance, see 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/)
Note: GP (General purpose lane)
Multi-year trends
In 2022, person throughput in both northbound and southbound directions continued to increase compared to 2021 due to the ongoing recovery of traffic volume in the wake of COVID-19.
In 2020, due to the statewide response to COVID-19 there was a significant reduction person throughput in 2020. In general, an HOV lane carries significantly more people than the general purpose lane adjacent to it.
From 2018 to 2019, HOV lanes in the central Puget Sound region network carried 65% more people than their adjacent GP lanes. However, overall person throughput in GP and HOV lanes appeared to stabilize in 2018 and 2019. More analysis is necessary to understand this change in the trend.
Annual highlights
In 2022, northbound and southbound person throughput did not change significantly compared to 2021. Most of the 10 monitored HOV locations showed a slight increase in person throughput compared to 2021. Person volume estimates are based on point locations and do not reflect the vehicle miles traveled on the central Puget Sound region freeway network as a whole.
In 2021, both northbound and southbound person throughput increased compared to 2020, due to the recovery of traffic volume in the wake of COVID-19. However, person throughput in 2021 was still lower than the pre-pandemic level. All 10 monitored HOV locations showed a slight increase in person throughput compared to 2020. Person volume estimates are based on point locations and do not reflect the vehicle miles traveled on the central Puget Sound region freeway network as a whole.
In 2020, all 10 monitored HOV locations showed significantly lower person throughput than in the previous five years due to the statewide response to COVID-19. There was a significant increase in GP person throughput at these locations, suggesting that travelers preferred to avoid proximity to other individuals in carpools and on public transit to reduce potential exposure to COVID-19. In addition, many businesses and government agencies' initiatives work from home policies during this time which be attributed to lower HOV numbers. Person volume estimates are based on point locations and do not reflect the vehicle miles traveled on the central Puget Sound region freeway network as a whole.
In 2019, changes in person throughput varied by location, with four of the 10 monitored locations showing higher person throughput than in 2018. Between 2018 and 2019, the magnitude of HOV person volume across the entire central Puget Sound HOV network decreased by approximately 1%, while person throughput in the general purpose lanes adjacent to HOV lanes decreased by about 3%. Person volume estimates are based on point locations and do not reflect the vehicle miles traveled on the central Puget Sound region freeway network as a whole.
In 2018, all of the 10 monitored locations showed lower person throughput than in 2017. Between 2017 and 2018, the magnitude of HOV person volume across the entire central Puget Sound HOV network decreased by approximately 16%, while person throughput in the general purpose lanes adjacent to HOV lanes decreased by about 6%. Person volume estimates are based on point locations and do not reflect the vehicle miles traveled on the central Puget Sound region freeway network as a whole.