What information is presented?
The "Lane Usage" links present data showing traffic volume, passenger volume, and speed, for the general purpose and HOV lanes on freeways in the central Puget Sound region. To facilitate analysis of various operating scenarios, data is shown for traffic in both directions and for four separate time periods:
• Morning peak period, 6:00 AM - 9:00 AM
• Mid-day, 9:00 AM - 3:00 PM
• Afternoon peak period, 3:00 PM - 7:00 PM
• Night, 7:00 PM - 10:00 PM
Each freeway segment is shown on two pages. The first page depicts weekday data. The second page depicts weekend data. Each page has three bullet points accompanying the tables. These bullet points summarize the data. The first describes general traffic conditions. The second describes HOV lane performance. The third discusses transit ridership patterns.
For this analysis the regional HOV system has been divided into nine separate segments. Data has been collected at specific locations on each of these segments. An effort has been made to use screenline locations that represent overall corridor performance. But it should be emphasized that conditions can vary considerably from one part of a corridor to another. The information presented provides a baseline for comparing current HOV lane and general purpose lane performance.
What does the data show?
• Freeways with HOV lanes are congested
• HOV lanes are most heavily used during peak commute times
• HOV lanes are most heavily used in the peak direction
• HOV volumes drop during mid-day
• Most HOV lanes carry more people than adjacent general purpose lanes
• Transit service is important component of regional HOV system
Methodology
The following pages contain several charts and graphics related to general purpose and HOV lane performance. The following assumptions and data sources were utilized in the creation of this material:
1. Speed and volume data was collected from the roadway loops maintained by the NW Region Traffic office of WSDOT. These same loops provide the real-time traffic flow data that WSDOT displays on its Web site.
2. Data is based on screenline locations, not overall corridors, unless otherwise specified. "Screenline," is a term used to describe a point where vehicles and passengers passing by are measured.
3. All data is from 2001. Weekday averages are based on Monday through Friday and weekends include both Saturday and Sunday. Yearly averages are based on a full twelve months of data.
4. The data used in this report are yearly averages over the indicated time periods. Conditions will vary as a result of incidents, special events, weather or other temporary occurrences.
5. Average Vehicle Occupancy (AVO) data by time of day is not available for all locations. In cases where no data was available, estimates were based on the best available data from other similar locations. All estimates are shown in italics.
6. Transit ridership data is from the spring of 2001. The totals shown include only regularly scheduled fixed route service. Paratransit, private charters, airport and hotel shuttle service, school buses and special event service have not been included. Weekend transit ridership figures are based on Saturday data. Per trip average loads have been calculated for routes where per trip ridership data was not available.
7. HOV lane construction was underway on I-405 from SR 527 to I-5 during the time that data was collected. Construction was also begun on the extension of the southbound HOV lanes on I-5 south of SR 516 in Kent during this time.