RTC has considered options for HOV in the I-5 corridor between Vancouver and Portland. This project assessed how the HOV options affect traffic operations and mobility in the corridor.
It also determined how an HOV lane could be built on I-5 without replacing the Interstate Bridge.
The implementation of an HOV facility in the corridor will require the bi-state agreement of multiple transportation agencies and jurisdictions working together for a common goal. This project was a collaborative effort of RTC, the Washington State Department of Transportation, C-TRAN, the City of Vancouver, Clark County, and the Oregon Department of Transportation.
High Occupancy Vehicle Lanes, also known as carpool lanes, are roadway facilities that provide preferential treatment for vehicles carrying more than one person and can include carpools, vanpools, and busses. Motorcycles may also use HOV lanes.
HOV facilities emphasize person movement rather than vehicle movement. They can offer the user of an HOV lane significant travel time reduction compared to travel in a general purpose traffic lane.
In addition, HOV facilities have high reliability and predictability compared to general purpose travel lanes.
Several areas of the country have chosen HOV strategies as one of the critical elements in addressing congestion. Puget Sound, Houston, Texas, and Boston, Massachusetts have taken different approaches to the use of HOV facilities in their regions. In the Portland region, the Oregon Department of Transportation has an I-5 Northbound HOV lane in operation during the PM peak period.
Interim HOV Lane
Interim HOV facilities are usually intended to be a temporary treatment. They are usually placed with the existing ROW on the freeway shoulder or through the conversion of a general purpose travel lane and separated from the general purpose travel lanes by a painted stripe. They can be located on the inside or outside shoulder of a freeway facility. Many times an interim facility will revert to general purpose traffic use during the off-peak period.
Barrier Separated HOV Lane
Barrier separated facilities are divided from the general purpose traffic lanes by a concrete barrier. Access to the facility is only at designated locations. Because of the physical separation from the general purpose traffic, barrier separated lanes generally have a higher degree of reliability than concurrent lanes. This type of facility may be used as an exclusive busway or may consist of a mix of HOV and bus vehicles. Barrier separated lanes may be concurrent flow with one lane of travel in each direction, or like the Houston system can consist of a single lane as a reversible flow facility.
Concurrent HOV Lanes
A concurrent HOV facility is a permanent treatment. It can be separated by a paint stripe or more typically, by a two to four foot at-grade buffer from the general purpose traffic. Since there is no barrier, concurrent HOV lanes can be accessed at any point to and from the adjacent general purpose travel lane. When there is a wide buffer separation, there are usually marked locations where vehicles are allowed to enter and exit the HOV lane.
Contraflow HOV Lane
A contraflow facility is a peak direction only facility. Underused off-peak direction capacity is converted to peak direction use during the commute period. Movable pylons or barriers are used to convert the off peak direction general purpose travel lane for HOV peak direction use. When not used as an HOV lane, pylons may be removed or barriers placed against the inside freeway median so the lane can revert to general purpose traffic use.
Because of the severe congestion problems on I-5.
The RTC Board adopted the Clark County High Occupancy Vehicle (HOV) Study and recommendations on December 1, 1998. The recommendations of the Clark County HOV Study included establishing HOV Goals and Policies and an HOV System Plan for Clark County.
The study recommendations consisted of a series of next steps for the I-5 corridor and other elements of the system plan. It included a decision to further investigate the potential for HOV in the I-5 corridor.
The I-5 corridor:
- Has the highest levels of traffic congestion
- Offers the most HOV travel time savings
- Has the highest carpool utilization, and
- Has the highest transit demand.
Full Corridor Option
- HOV lane in each direction between 134th Street in Clark County and Going/Lombard Streets in Portland
- Reversible HOV lanes on the Interstate Bridge
- Reversible HOV lane through Delta Park
Delta Park Option
- Reversible HOV lane between Lombard Street and Jantzen Beach
- Will use current northbound HOV lane from Going Street and Marine Drive
- No HOV lanes on the Interstate Bridge
- No HOV lanes in Washington
Queue Bypass Option
- No HOV lanes on the Interstate Bridge
- Southbound AM peak HOV lane between 134th Street and Interstate Bridge
- Northbound PM peak HOV lane between Going Street and Marine Drive
- Assess impact of restarting the HOV lane after crossing the Interstate Bridge
- The existing lift spans cannot lift the weight of a typical concrete barrier.
- The Bridge can be retrofitted to lift a concrete barrier, but several operational problems remain.
- There are narrow lanes on the Interstate Bridge.
- There are narrow sections of I-5 through Delta Park.
- Peak direction HOV lanes on the Interstate Bridge will not take away the current three general purpose lanes.
- Traffic interaction on I-5 between SR-500 and the Interstate Bridge must be considered.
- How can HOV lanes be added to the Interstate Bridge?
- How can a southbound HOV lane be added through Delta Park?
- Should the new lanes for the I-5 widening project north of Main Street become HOV lanes?
- What are the safety and operational implications of reversible, barrier-separated HOV lanes on the Interstate Bridge?
The three options underwent detailed analysis that:
- Estimated use of the HOV lane by carpools, vanpools, and buses.
- Assessed traffic operations for the HOV lane and for general purpose traffic lanes.
- Evaluated merging and weaving conditions along the corridor and at the beginning and end of the HOV lane.
- Determined the short term and long term impacts of HOV lanes on I-5.
- Assessed the impact on freight mobility.
After a prefered HOV option is selected, additional information was developed including:
- Conceptual and preliminary design.
- Enforcement and incident management.
- Capital and operating costs.
- Begin Study
- Develop Range of HOV Options
August 1999
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- Public Open House
- Feasiblity Analysis of HOV Options
- Select HOV Strategies for Detailed Analysis
- Evaluate Promising HOV Alternatives
- Public Open House
- Select Preferred HOV Alternative
- Public Open House
- Adopt Preferred HOV Alternative
- Complete HOV Design
- Implementation
The I-5 High-Occupancy Vehicle Operational Study Executive Summary with Technical Advisory Committee Findings is now available online. The full report should be made available shortly.
If you’d like to communicate with RTC regarding this study, or get on our mailing list for future meetings, please e-mail i5hov@rtc.wa.gov or call 360-397-6067.
Thanks!
       
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