The Washington State Department of Transportation evaluated the hours of operation of freeway high occupancy vehicle (HOV) lanes in the Central Puget Sound region. These lanes were previously reserved for carpools, vanpools, motorcycles and buses 24 hours per day, seven days per week. The data and analysis generated in this study led WSDOT to recommend that we:
• Open freeway high occupancy vehicle lanes to all traffic from 7 PM to 5 AM on I-405, SR 167, SR 520 (east of I-405), I-90 (east of Mercer Way)
• Pursue a high occupancy toll (HOT) lane strategy on I-405 and SR 167 to manage existing roadway space more efficiently. HOT lanes would allow single-occupancy vehicle drivers to use the HOV lane midday if they pay a fee.
Why did WSDOT evaluate HOV lanes?
We hear a lot about HOV lanes. We received many suggestions asking that we open these lanes to general traffic during non-peak times. These suggestions deserved to be evaluated to see if the effectiveness and efficiency of the highway system can be improved. The data and analysis from this study led WSDOT to propose changes to Eastside freeway HOV lane operations to:
• Make the best possible use of existing highway capacity
• Ensure transit and HOV lane reliability now and into the future
• Foster public support for HOV lanes over time
What key questions did the study address?
• Are all HOV lanes effective?
• Can the HOV lanes be opened to general traffic at some times and still provide reliable service for buses, vanpools and carpools?
• The region made HOV lane commitments to the Federal government in exchange for funding. If we open the lanes will the Federal government impose a financial penalty on the region?
• What are the environmental implications of opening the lanes?
The evaluation included:
• Safety and freeway operations
• Environmental impact
• Public comments
• Impact on transit, carpools and vanpools
• Legal and regulatory obligations and impacts
Which HOV lanes were evaluated?
Mainline freeway HOV lanes:
• I-5 (Everett - Northgate)
• I-5 (Federal Way - Seattle)
• I-90 (Bellevue - Issaquah)
• SR 167 (Auburn - Renton)
• I-405 (Lynnwood - Bellevue - Tukwila)
• SR 520 (Bellevue - Redmond)
What lanes were not examined in this study?
WSDOT did not evaluate the following HOV facilities and is not considering opening these lanes to general-purpose traffic:
• HOV lanes to transit-only facilities
HOV lanes that provide access to transit-only facilities will not be examined. General-purpose traffic is not allowed into transit-only facilities therefore there is clearly no need to open these lanes.
• Arterial (non-freeway) HOV lanes
Local communities, not WSDOT, typically operate these lanes. In many cases these HOV lanes are only in effect during specific hours. Traffic patterns and congestion on these lanes often differ from those on freeways. In locations where transit pull-outs do not exist the HOV lanes allow buses to safely stop without blocking general-purpose traffic.
• Ramp meter bypass HOV lanes
Ramp meter bypass lanes were designed to safely accommodate HOV traffic flow when ramp meters are operating. They were not designed to handle general traffic flow. Safety would be compromised if these bypass lanes were opened to general traffic. In addition, ramp meters allow us to manage traffic flow anytime congestion is present. Opening ramp meter bypass HOV lanes to all traffic would make congestion worse.
• I-90 from east of Mercer Way to 4th Avenue South (Seattle stadiums)
WSDOT and Sound Transit are developing an environmental impact analysis on segments of this freeway. Changes to HOV lane operations are best considered in the environmental process already underway. [link to I-90 two way transit project page]
• SR 509 (Seattle, First Avenue South Bridge northbound approach)
These HOV lanes function much like arterial HOV lanes. They allow HOVs to pass traffic to get to a bridge or traffic signal. Opening the lanes to general traffic would increase merging, create more congestion approaching the bridge or traffic signal and decrease safety. As a result they will not be considered in this evaluation.
• SR 520 from I-405 (Bellevue) to the Evergreen Point Bridge
These shoulder HOV lanes can safely accommodate three-person HOV traffic flow, but not general traffic flow. In addition, opening the westbound shoulder lane to general traffic would increase congestion by increasing the amount of merging traffic where the HOV lane merges into traffic near the Evergreen Point Bridge.
• I-5 express lane HOV lanes and HOV direct access lanes (downtown Seattle)
HOV lanes on the I-5 express lanes are designed to safely accommodate HOV traffic flow. Opening these lanes to general-purpose traffic would reduce safety by increasing lane changing and weaving. Downtown traffic circulation is designed with express lane HOV lanes in mind. Opening these lanes to general-purpose traffic would require examination and likely revision of downtown Seattle traffic circulation.
• Sound Transit direct access ramps
These ramps are not currently constructed but will be over the next five years. Once constructed these ramps will provide direct access to inside (left hand) HOV lanes. These ramps have been designed to standards negotiated with the Federal Highway Administration with use by HOV, not general-purpose traffic, in mind.
• SR 167 northbound queue jump to northbound I-405 (Renton)
This queue jump makes SR 167 HOV lanes more usable. HOV traffic that uses the queue jump merges with general-purpose traffic on the ramp before joining northbound I-405 traffic. Opening this queue to all traffic would increase weaving and merging on the ramp, cause more congestion, and reduce safety.
When did WSDOT decide to start opening some carpool lanes to all traffic at night?
On January 16, 2003 the Transportation Commission adopted a plan to open Eastside HOV lanes at night and explore high occupancy toll lanes. Before opening the lanes to all traffic, WSDOT completed $1.6 million in safety improvements. These improvements included the installation of left-hand rumble strips, increased clear zones, and added guardrail. WSDOT made these changes after consultation with the Federal Highway Administration. In addition, the Commission decided to explore converting I-405 and SR 167 HOV lanes to high occupancy toll (HOT) lanes during mid-day off-peak hours.
Transportation Commission Chairman Aubrey Davis said, "These moves allow us to better manage the freeways to maintain efficiencies for transit and carpools, while increasing convenience and safety for drivers outside of peak travel times. If we are to handle future growth of general-purpose and HOV traffic, we need a future-oriented strategy to manage traffic within the capacity that will be available."
"We heard from many citizens on these topics," added Transportation Secretary Doug MacDonald. "One thing I want to stress about both of these changes is that they are meant to improve conditions for drivers in all lanes by maximizing available capacity as well as maintaining speed and reliability for transit, vanpools and carpoolers."
Specifically, the Commission approved a four-point resolution that:
• Approves nighttime use of HOV lanes on eastside highway segments for a two year demonstration
• Pursues off-peak management strategies such as HOT lanes
• Requires quarterly updates on the progress of the HOV lane changes and HOT lane evaluation
• Commits the department to:
• Support completion of the HOV core system in Puget Sound
• Continue to restrict access to HOV direct access ramps for transit
• Continue working with transit agencies to identify additional system improvements
• Reconsider hours of operations if the change results in unacceptable impacts to transit operations
The decision came after the most comprehensive review of the HOV lanes conducted by WSDOT. The evaluation considered safety and freeway operations, environmental impacts, impacts to transit, carpools and vanpools and legal or regulatory obligations and public comment.
Where did WSDOT open most Eastside carpool lanes to all traffic at night?
WSDOT opened HOV lanes on Interstate 405, State Route 167, State Route 520 and Interstate 90 (east of I-405) in August 2003.
How has opening Eastside carpool lanes to all traffic at night affected traffic and safety?
WSDOT is closely monitoring and studying the affect of opening carpool lanes to all traffic at night. A preliminary report (pdf 1 mb) was issued in December 2004.