II. Decision-Making Process
III. Selected HOV Option
IV. Key Findings
V. Bi-State Policy Issues
The Regional Transportation Council (RTC), in conjunction with the Washington State Department of Transportation (WSDOT) and the Oregon Department of Transportation (ODOT), conducted an operational and feasibility study of High Occupancy Vehicle (HOV) lanes on I-5 between Clark County, Washington (134th Street), and Portland, Oregon. This was the next step of the Clark County Regional HOV Study, which identified a need to move forward with a more detailed feasibility and operational approach to implementing HOV facilities in the I-5 corridor. The study was charged with developing an HOV option that could be implemented in the corridor without replacing the Interstate Bridge and without the construction of any widening through Delta Park. It also follows closely the successful I-5 Northbound HOV Lane Pilot Project implemented by ODOT in October 1998. That project currently carries 2,400 persons per lane per hour, more than either of the general purpose (GP) lanes, and saves 5-7 minutes per vehicle. It also has a 70 percent public approval rating.
This effort was also strategically coordinated with the imminent construction work in Washington to widen I-5 between Main Street and 99th Street (and eventually to 134th Street) to add another lane in each direction. The study findings will provide guidance to WSDOT regarding the use of the new lane capacity.
The Base Case for this study was called the "No New HOV" alternative. It consisted of the current I-5 transportation network and projects contained in the Metropolitan Transportation Plan (MTP) outside of the I-5 Corridor. It also included the I-5 widening in Washington and the existing northbound HOV lane between Going Street and Delta Park in Oregon that operate during the PM peak period only. During the study process, several HOV strategies and alternatives were developed and considered. These included Queue Bypass options (no HOV on the Interstate Bridge, HOV lanes at selected locations in Washington and/or Oregon), a Delta Park only option (AM peak period), and a Full Corridor option which carried reversible HOV lanes across the Interstate Bridge.
A public opinion survey of 800 Clark County residents was conducted as part of the I-5 HOV Operational Study. The survey provided representative data of attitudes, knowledge, and behavior regarding HOV lanes.
The survey concluded that almost all bi-state travelers (96%) were aware of the existing northbound I-5 HOV lane. Two-thirds of those using the HOV lane reported saving travel time.
Slightly more than 50 percent supported HOV lanes as an effective traffic management strategy. Most respondents (59%) favored implementing HOV by adding the lane instead of converting an existing general purpose lane for HOV. Two-thirds supported peak-period operation of HOV lanes, while 23 percent supported 24-hours-a-day, 7-days-per-week operation of the HOV lane. Most of those surveyed (80%) agreed that the HOV lanes should have a strong enforcement program.
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RTC was the project lead for the overall study and the management of work tasks. The I-5 HOV Technical Advisory Committee provided expertise and comment on the technical analysis and was made up of staff from the Washington State Department of Transportation, City of Vancouver, Clark County, C-TRAN, Metro, and the Oregon Department of Transportation. In addition, the two state transportation departments provided expert advice regarding the operation, design, and characteristics on HOV and their state facilities. Findings and recommendations of the TAC were forwarded to the Regional Transportation Advisory Committee for their comment and review prior to consideration by the RTC Board.
The RTC Board received the study finding and conclusions and forwarded them to the Bi?State Transportation Committee for their discussion. The role of the Bi-State Transportation Committee was to consider the study findings and conclusions and to recommend any bi-state action to the RTC Board and Joint Policy Advisory Committee on Transportation (JPACT) regarding an HOV facility in the I-5 corridor. Study findings will be forwarded to the I-5 Trade Corridor Study.
Figure ES-1. Decision-Making Process
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After analysis and screening of several HOV options in the I-5 corridor, three non-bridge HOV options were evaluated for detailed operational analysis: Washington only HOV, Oregon only HOV and a bi-state HOV option consisting of an HOV facility in Washington and Oregon with no HOV on the Interstate Bridge. All HOV options resulted in travel time savings and higher HOV person demand than the base case, which has no AM southbound HOV. However, of the three options, the bi-state HOV option offered the highest travel time savings and HOV person demand. A bi-state HOV facility in the I-5 corridor resulted in significant mobility improvement in the corridor for transit and other shared ride users.
Figure ES-2. Selected HOV Lane Configuration
The selected bi-state HOV option developed in the I-5 corridor is based on an analysis of traffic operations, safety, and design issues for the HOV options studied. The PM HOV option consists of the current NB HOV lane between Going Street and Marine Drive. The AM HOV option consists of a southbound HOV facility in Washington from 134th Street to Mill Plain Boulevard, no HOV lane across the Interstate Bridge, and an HOV lane in Oregon from Marine Drive to Lombard Avenue. The southbound AM option is described below:
- Two general-purpose travel lanes plus an HOV lane from 134th Street to SR 500. This would also include an auxiliary add/drop lane from 134th Street to SR 500.
- Added capacity for HOV from SR 500 to Mill Plain Boulevard. This would be accomplished by reconfiguration of the existing lane and shoulder striping to provide an additional through (HOV) lane in this segment. There are two possible design options for this reconfiguration:
- a new outside general purpose lane would be added from SR 500 south to the Interstate Bridge and the inside general purpose lane would be utilized for HOV; the HOV lane designation would drop at Mill Plain Boulevard to allow all vehicles to use the inside lane across the bridge; or
- An HOV lane would be added to the inside median which would then merge with general purpose traffic before crossing the Interstate Bridge. The tradeoffs between the two design options have been defined and should be considered in the decision-making process for HOV implementation.
Interstate Bridge No HOV lane across the bridge.
Added capacity for HOV from Marine Drive to Lombard Avenue. The I-5 HOV Operational study's original goal was to analyze the feasibility of implementing an HOV lane without widening the corridor through Delta Park. The study examined accomplishing this via a reversible lane using a movable barrier. While the construction cost for such a concept would be lower than the cost of widening, ongoing operations and maintenance costs may eventually result in higher overall costs for the reversible lane compared to widening. It was determined that HOV should not be implemented without a major widening of the corridor due to overall cost, safety, and operational concerns. Southbound HOV capacity should be provided by constructing an additional travel lane on Interstate 5 from the Delta Park interchange to Lombard Ave. This project is included in the Metro's Regional Transportation Plan (RTP) strategic plan and ODOT has begun preliminary work on the project. The project was also recommended by the I-5 Trade Corridor Leadership Committee.
PERFORMANCE OF SELECTED HOV ALTERNATIVE
The selected southbound HOV option compares favorably against the following performance measures:
- HOV would save users one minute per mile and a minimum of 5 minutes overall (meets the total travel times savings, but not travel time savings per mile in 2003, well-met in 2020)
- HOV lane is forecast to carry at least 600 vehicles per hour (would be met southbound in the opening year (2003) as well as in 2020)
- The HOV lane is expected to carry more persons per hour than any adjacent GP lane (would be met southbound in 2003 as well as in 2020)
- General purpose lanes are currently experiencing LOS E/F conditions for at least one peak hour in each peak direction.
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Of the HOV options identified for detailed analysis, the bi-state HOV option had the most benefit to mobility in the I-5 corridor, by providing the highest travel time savings and HOV person demand. The analysis results are summarized in the following table:
AM 2 Hour: Summary of HOV Options1 Alternative Vehicles in HOV Lane Bus Ridership Persons in HOVs Persons per GP lane HOV Lane Time Savings (Minutes per Vehicle) HOV Lane Time Savings (Minutes per Mile) Base-Case: No New HOV N/A 1,720 4,000 ---- ---- N/A Washington only 1,4002 1,800 4,900 3,850 7-8 1.1 Oregon only HOV 1,000 1,760 4,370 3,600 1.8 0.7 HOV in Washington and Oregon 1,530 1,900 5,120 3,850 8-10 1.1-1.2
1 Measured at Marine Drive
2 Measured at Mill Plain Boulevard
In addition, the study finds that:
- A Bi-State I-5 HOV facility provides the greatest mobility by increasing the number of persons using the corridor and reducing overall vehicle hours of travel compared to other HOV alternatives and to the provision of general purpose capacity.
- The study findings are consistent with the adopted MTP and the Clark County HOV Study (December 1998).
- The I-5 Corridor is a National Priority Trade Corridor and HOV facilities should be considered within the context of the overall function of I-5 and considered further during the development of the I?5 Corridor Development and Management Plan.
- Persons using the HOV lane exceed the number of persons per lane in the adjacent general purpose lane.
- HOV lanes show significant travel time savings for HOV users.
- Southbound between SR 500 and the Interstate Bridge, HOV scenarios which added a lane rather than converting an existing lane showed less congestion.
- In 2020, southbound AM peak congestion occurs for most of the corridor between 134th Street and the Interstate Bridge.
- The Interstate Bridge is the most significant bottleneck in the corridor. The bridge affects peak-hour traffic causing significant queuing which will grow worse by 2020.
- In the southbound direction, the bottleneck at the Interstate Bridge is exacerbated by another bottleneck downstream at Delta Park. The combination of these two bottlenecks causes significant queuing.
- Approximately one mile of queuing, similar to that currently experienced, is expected through Delta Park in 2020.
- A review of HOV alternatives shows a southbound HOV lane between 134th Street and the Interstate Bridge and through Delta Park saves HOV users approximately 8 to 10 minutes per vehicle compared to general purpose lanes, and over one minute per mile.
- Most of the projected HOV time savings occurs in Washington (7-8 minutes per vehicle).
- Southbound travel time savings through Delta Park is limited by the capacity constraints at the Interstate Bridge.
- The northbound PM peak reversible HOV lane across the Interstate Bridge significantly increases congestion in the southbound direction in 2020 due to the loss of a southbound general purpose lane.
- Benefits gained by having a northbound reversible HOV lane on the southbound span of the Interstate Bridge are more than offset by the disbenefits of increased congestion in the southbound direction in the PM peak period.
- Any reversible lane option on the Interstate Bridge reduces travel lane width, impacts traffic operations, and is difficult to design and manage with an operating lift-span drawbridge.
- A reversible lane through Delta Park was a design option working within the existing bridge structures over the Columbia Slough and Columbia Boulevard. The substandard nature of its design, including lack of shoulders and left-hand merging areas, presents significant safety and operational concern. In addition, the project requires a $6 million capital cost and annual operating costs of $750,000.
- The cost to implement HOV in Washington is approximately $362,000.
The study concluded that:
- No further consideration should be given for a PM peak northbound HOV lane in Washington unless warranted by congestion or if new capacity is provided by a replacement of the Interstate Bridge.
- No further consideration should be given for a reversible HOV facility across the existing Interstate Bridge spans.
- A minimum of three general purpose lanes should be provided in each direction in Washington between SR 500 and the Interstate Bridge.
- Although the selected HOV option north of SR 500 is 2 general purpose lanes plus an HOV lane, the conversion to 3 general purpose travel lanes plus and an HOV lane should considered when warranted by congestion or when new bi-state capacity is provided by the replacement of the Interstate Bridge.
- A southbound, AM peak period HOV lane through Delta Park should be accomplished via widening of the corridor to achieve three full-time through lanes within acceptable design standards rather than by a peak-only reversible lane.
- Widening of I-5 southbound through Delta Park would provide AM peak period HOV capacity and non-peak freight capacity.
The I-5 Trade Corridor Study's Corridor Development and Management Plan should address these conclusions as part of the overall Bi-State decision-making process on the I-5 corridor, including the considerations for any new Columbia River crossing capacity. A summary matrix of the study findings and conclusions by segment is included at the end of the executive summary.
The following Agency Issues will need discussion and resolution prior to further consideration of an HOV configuration in the corridor:
- The implementation of an I-5 Bi-State HOV Corridor will require bi-state consensus.
- The study findings should be considered in the context of the current I-5 widening construction project between 99th Street and SR 500.
- The study findings should be advanced through the decision-making process, including the I-5 Trade Corridor Study.
- Lane configurations inclusive of HOV on southbound I-5 from SR 500 to the Interstate Bridge require resolution of design issues.
- Design of HOV southbound through Delta Park requires resolution of design issues to determine how an HOV lane through Delta Park should be implemented as part of major widening through Delta Park.
- The analysis results for a reversible lane concept in Oregon should be forwarded for consideration in the Delta Park widening discussions.
- The I-5 HOV Operational Study findings are consistent with WSDOT HOV policy regarding travel time savings, lane use, added capacity for HOV and segment length, but not time-of-day operation.
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- An Intergovernmental agreement between RTC and Metro states that JPACT and RTC Board, "Metro and RTC shall take no action on an issue of bi-state significance without first referring the issue to the Bi-State Transportation Committee for their consideration and recommendation." The findings of the I-5 HOV Operational Study is being forwarded to the Bi-State Transportation Committee for their discussion and recommendation. Any recommended action by the Bi-State Transportation Committee will go to RTC and JPACT for their consideration.
- The I-5 HOV Operational Study identifies HOV as a viable short-term strategy; it does not address the HOV in the corridor with an Interstate Bridge replacement. The I-5 Trade Corridor Study will be addressing the long-term role of HOV in the corridor in the context of new bridge capacity. The study findings and conclusions should be forwarded to the I-5 Trade Corridor Study process.
- The study findings must be considered in the context of the current I-5 widening construction project north of SR 500. Study findings will provide guidance to WSDOT regarding the use of new lane capacity currently being constructed.
- The I-5 HOV Operational Study findings are consistent with WSDOT HOV policy regarding travel time savings, lane use, added capacity for HOV and segment length. State policy calls for full time HOV lane operation. However, the study recommends peak period only HOV in the I-5 corridor.
- Funding to implement the widening to accommodate HOV through Delta Park should be considered in the Bi-State funding discussions for the I-5 corridor.
Summary of I-5 HOV Operational Study Findings and Conclusions
Finding Conclusion Bi-State Corridor Bi-State I-5 HOV facility provides the greatest mobility of all alternatives studied. A southbound, AM peak period HOV facility should be provided in the I-5 Bi-State corridor. In the PM peak, the current northbound HOV lane between Going Street and Delta Park is preferred. The I-5 Corridor is a National Priority Trade Corridor and HOV facilities should be considered within the context of the overall function of I-5. The I-5 Trade Corridor Study should receive and address these findings as part of the overall Bi-State decision-making process on the I-5 corridor. Washington Portion In 2020, southbound AM peak congestion occurs for most of the corridor between 134th Street and the Interstate Bridge. The selected HOV option consists of an AM southbound HOV facility from 134th Street to Mill Plain Boulevard. A southbound HOV lane between 134th Street and the Interstate Bridge and through Delta Park is projected to save HOV users approximately 8 to 10 minutes per vehicle compared to general purpose lanes in 2020, and over one minute per mile. Most of the projected HOV time savings occurs in Washington (7-8 minutes per vehicle). The minimum operable segment in the AM peak is from 78th Street to Mill Plain Boulevard. The Interstate Bridge meters traffic in each direction, affecting downstream queues both currently and in 2020. No further consideration should be given for a northbound HOV lane in the PM peak on the Washington side. A northbound HOV lane north of the Interstate Bridge should be considered when congestion levels warrant an HOV lane or if and when the Interstate Bridge is replaced. Interstate Bridge The Interstate Bridge meters traffic in each direction, affecting downstream queues both currently and in 2020. The I-5 Trade Corridor Study should receive and address these HOV considerations for any new Columbia River crossing capacity. Benefits gained by having a northbound reversible HOV lane on the Interstate Bridge are more than offset by the disbenefits of increased congestion in the southbound direction in the PM peak period. No further consideration should be given for a reversible HOV facility across the Interstate Bridge. Any reversible lane option on the Interstate Bridge reduces travel lane width, impacts traffic operations, and is difficult to design and manage with an operating lift-span drawbridge. No further consideration should be given for a reversible HOV facility across the Interstate Bridge. Oregon Portion Approximately one mile of queuing, similar to that currently experienced, is expected through Delta Park in 2020. Design of HOV southbound through Delta Park requires resolution of design issues and the implementation of HOV through Delta Park should be implemented as part of major widening through Delta Park. A reversible lane design option through Delta Park has a substandard design, lack of shoulders and left-hand merging areas, presenting significant safety and operational concerns along with significant ongoing operational costs. A southbound, AM peak period HOV lane through Delta Park should be accomplished via widening of the corridor to achieve three full-time through lanes within acceptable design standards.
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- Prepared for:
- Southwest Washington Regional Transportation Council
- In Cooperation with:
- Washington State Department of Transportation
Oregon Department of Transportation
City of Vancouver
- Submitted by:
- Parsons Brinckerhoff Quade and Douglas
David Evans and Associates
Pacific Rim Resources
HS Public Affairs
Innovative Transportation Concepts
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