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Freeway Management and Operations Handbook |
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Chapter 9 – High Occupancy
Vehicle Treatments
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Agency or Group | Potential Roles and Responsibility |
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State Department of Transportation |
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Transit Agency |
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State Police |
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Local Police |
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Local Municipalities |
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Rideshare Agency |
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Metropolitan Planning Organization (MPO) |
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Federal Agencies – FHWA and FTA |
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Other Groups |
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The development of an operations plan is foremost in the success of the HOV facility. It should be noted that the development of an operations plan cannot be done in isolation, but needs close integration with the facility's enforcement plan (1). The plan should also address the various policy issues associated with HOVs, including those discussed below:
This addresses the type of HOV facility, and it has a direct and significant impact on other elements of the plan such as the ingress and egress and enforcement. The operation of separated HOV roadways may be reversible or two-way. The facility can be restricted to HOVs during peak periods only or throughout the day. Limiting access to a reversible HOV facility is crucial if the facility is to be operated in a safe and efficient manner. A system of gates must be considered at each end (and at any intermediate access points) to prevent wrong-way traffic from entering the facility, if located on a freeway. In addition to these features, this type of facility should also have a system of changeable message signs (CMS) that inform commuters as to the operational status of the facility (open or closed).
The HOV facility provides operators and managers the flexibility to match the vehicle eligibility (and the vehicle occupancy requirements) to the lanes. Further, each can be changed to maintain the proper balance if necessary. Vehicle eligibility (i.e., what types of vehicles can use the facility) is one of the first issues that must be determined to develop the Operations Plan. Various types of vehicles can be considered for the use on the HOV facility including:
Vehicle occupancy (e.g., 2+ or 3+) should be examined against the demand for the facility to estimate the impact the occupancy requirements may have on traffic flow. The goal is to implement HOV facilities in such a way that balances the flexibility of HOV growth and the public perception as to the use of a facility. An initial minimum vehicle occupancy requirement must be selected to optimize the efficiency of the facility. The selection must allow for growth in traffic volumes as more commuters choose to switch to carpooling arrangements and take advantage of the travel time and fuel savings. Title 23 United States Code 102(A) allows State departments of transportation to establish the minimum occupancy requirements for vehicles operating on HOV lanes; except that no fewer than two occupants per vehicle may be required and that motorcycles and bicycles shall not be considered single occupant vehicles. Retaining the potential to carry more people over time offers important operational flexibility. At the same time, though, public perception of the adequacy of HOV lane usage must also be addressed. Peak hour HOV traffic volumes need to be high enough to help mitigate public concerns over underutilization of HOV facilities. The positive aspect of 2+ eligibility is that a staged resource of commitment to ridesharing is being established. Less work is involved in forming a 2+ carpool versus a 3+ carpool, and the base volume to draw from is considerably greater. There may be less eventual resistance to adding a third passenger than to forming an initial 3+ carpool.
Subsequent changes in occupancy requirements need to be weighed with projected future demand. Implementing an operational change from 2+ to 3+ occupancy could reduce vehicular demand by as much as 75 to 85 percent. This could be severe if only a 10 to 20 percent reduction in demand is necessary for the near future. A new HOV 3+ lane typically may carry only a few hundred peak-hour vehicles, while an adjacent freeway lane is carrying 1500 to 2000 peak-hour vehicles. Even though the HOV lane may be carrying more peak-hour person trips than an adjacent general purpose lane, the traveling public may perceive the lane to be underutilized. Additionally, there is the potential political difficulty in making a change from 2+ to 3+, as evidenced by the fact that very few such attempts have been successful. Varying occupancy requirements by time-of-day is another possibility.
Another consideration is regional consistency. It is the exception to have different occupancy (or eligibility) requirements on different facilities or in different corridors within the same metropolitan region.
Hours of operations for an HOV facility may be characterized as:
A number of factors, including geometric design, volumes of HOV and mixed-flow traffic, hours of congestion, and regional consistency will influence HOV operating hours. Twenty-four hour HOV use of priority facilities is sometimes preferred, because violations tend to be lower and there is less motorist confusion. Also, 24-hour use may provide a greater overall incentive for the formation of new carpools. Some HOV facilities, such as reversible lanes, may not be conducive to 24-hour operation. The hours of operation for reversible facilities must allow time for a variety of necessary functions, such as clearing the lane, moving gates, and changing signing.
Part-time operation provides benefits only during the peak hours of defined need, allowing all traffic to use the lanes during other periods. This approach can reduce enforcement requirements and minimize public criticism during periods when the HOV lane appears empty. Part-time use of a shoulder as an HOV facility should be implemented only after careful consideration of operational and safety problems. The right shoulder HOV facility differs from a part-time HOV lane that reverts to mixed-flow use during off-peak periods, in that the shoulder serves as a refuge for emergency breakdowns. Its use needs to be limited to a small number of vehicles because of the inherent conflicts at right side entrance and exit ramps. The shoulder facility requires special delineation and signing, and involves separate enforcement problems for both peak and off-peak periods. Motorists may tend to use the shoulder as a freeway lane during off-peak hours when it should be used as a shoulder.
Marketing and promoting the HOV facility is paramount to its successful implementation. More than one facility has either failed or had significant setbacks as a result of not informing or involving the public. The process of successful marketing of HOV facility includes (1):
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Enforcement of vehicle-occupancy requirements and other policies are critical to the successful operation of HOV facilities. HOV enforcement programs help ensure that operating requirements, including vehicle-occupancy levels, are maintained to protect HOV travel time savings, to discourage unauthorized vehicles, and to maintain a safe operating environment. Visible and effective enforcement promotes fairness and maintains the integrity of the HOV facility to help gain acceptance of the project among users and non-users (8).
Public acceptance of an HOV project is closely linked to the perception that the facility is well used and that the vehicle occupancy requirements are enforced. Support for an HOV facility will be lessened if commuters traveling in the adjacent freeway lanes feel the privilege of using the HOV lanes is being abused. Ensuring that the project design includes adequate and safe enforcement areas, and that visible ongoing enforcement is provided are important to the success of an HOV project (1).
Detection and apprehension of violators, and effective prosecution of violators, are essential. Therefore, law enforcement personnel with full capability to issue citations must be employed on HOV facilities. Moreover, police officers help ensure the safe and efficient operation of the facility. Depending on the type of facility and priority users, the potential safety and operational problems caused by vehicle breakdowns, wrong way movements and/or other vehicles' encroachments into the HOV facility may have an adverse impact on operations and must be a concern of the enforcement authority.
Effective enforcement usually includes a number of components. The following general elements should be considered in developing and conducting an enforcement program (8):
Enforcement strategies for HOV facilities can generally be categorized into four basic approaches – routine enforcement, special enforcement, selective enforcement and self-enforcement. All of these strategies may be appropriate for consideration with the various types of HOV projects.
A variety of enforcement techniques can also be used to monitor HOV facilities. These techniques focus on providing surveillance of the lanes, detecting and apprehending violators, and issuing citations or warnings to violators. Examples of approaches include stationary patrols, roving patrols, team patrols, multipurpose patrols, electronic monitoring, citations or warning by mail. Most areas use a combination of enforcement techniques.
A 1988 Texas Transportation Institute study (reference 9) of the enforcement procedures for HOV lanes determined the following key concepts related to effective HOV enforcement:
Where enforcement is difficult to accomplish, or perceived as being unsafe, police may avoid apprehending violators, resulting in increasing numbers of illegal vehicles using the lane. Where enforcement has been a problem, 60 percent or more of the vehicles that used the lanes were violators. Experience suggests that steady doses of routine enforcement, combined with moderate application of special enforcement, can generally keep violation rates on exclusive HOV facilities in the 5 to 10 percent range. Heavy, consistent doses of special enforcement would be necessary to have violation rates below 5 percent. There are locations where no amount of enforcement can bring violation rates to an acceptable level (10).
In some metropolitan areas, programs have been initiated where motorists can call in to report HOV facility violators. Appropriate literature is sent to frequent violators, and enforcement personnel can make a point of watching for these vehicles in the HOV lane. These "so called" HERO programs can be helpful in reducing violation rates. Also, a system of video cameras combined with officer observation may be considered for non-occupancy infractions such as speeding or toll evasion (where pricing is applied), where state laws permit such technology. Currently, no state allows video for occupancy infractions because the system cannot be supported as fool-proof in the courts. Another factor that will have a positive impact on the violation rate is the cost of the fine for a violation. Fines exceeding $250 for first offenders have been used, significantly lowering the violation rate.
As discussed in Chapter 4, evaluating the effectiveness of HOV treatments (or any freeway management strategy for that matter) should not be considered a one-time activity, but should be part of a periodic review of the effectiveness of the component and of the overall system. In addition to providing information to the sponsoring agencies on the effectiveness of the treatment(s), the information would be helpful in communicating the effectiveness of the project to the public and enhancing a general understanding of the role that the HOV project has performed.
For each objective associated with the HOV program, the appropriate measure(s) of effectiveness should be identified, along with the desired threshold level of change that will be used to determine if the facility has met the objective. Commonly used objectives (i.e., for new HOV projects that add a lane to the freeway) and measures of effectiveness are identified in Table 9-4.
Objective | Measures of Effectiveness |
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Other issues that may be of concern with the development and implementation of an HOV treatment include the following:
HOT lanes have many of the same issues as noted above. Additionally, there are a number of unique concerns. For one, HOT lanes may involve the introduction of tolls for the first time. This may require DOTs to establish new legal and institutional structures and operational capabilities before HOT lane projects can actually be implemented. They may also introduce unfamiliar project financing and operational approaches. Most importantly, they introduce public relations challenges that have the potential to bring HOT lane initiatives to an abrupt halt at nearly any stage of their development (5).
Several other important choices face transportation officials and policy makers as HOT lane projects become more clearly defined. These decisions can have repercussions on design, as well as equity issues and are likely to include (5):
Information on the numerous freeway HOV implementations across the nation can be found at the Federal Highway Administration's High Occupancy Vehicle website, www.ops.fhwa.dot.gov/travel/traffic/hov/index.htm. Two case studies – involving a change in occupancy requirements and HOT lanes – are described below.
Opening in 1973, the El Monte Busway on the San Bernardino (I-10) Freeway is the oldest high-occupancy vehicle (HOV) facility in the Los Angeles area. In 1999, the California Legislature approved Senate Bill 63 (SB 63), lowering the vehicle-occupancy requirement on the El Monte Busway from three persons per vehicle (3+) to two persons per vehicle (2+) full time. The legislation directed the California Department of Transportation (Caltrans) to make this change on January 1, 2000 as part of a temporary demonstration project, which was to extend until June 30, 2001. The legislation also required Caltrans to monitor and analyze the effect of this change on the operation of the freeway and the Busway. Based on the operational effects of the change, as documented in the Caltrans operational study (as summarized below), new legislation was passed increasing the vehicle-occupancy requirement back to 3+ during the morning and afternoon peak periods and maintaining the 2+ requirement at all other times, effective July 24, 2000.
The Caltrans monitoring program tracked travel speeds, vehicle volumes, and person movement on both the Busway and the general-purpose freeway lanes. Conditions prior to implementation of SB 63, during the 2+ demonstration, and after the change to the 3+ peak/2+ off-peak requirements were monitored by Caltrans. The Caltrans assessment focused on the morning and afternoon peak periods, when demands on the freeway system are greatest and traffic volumes are highest. Further, the analysis focused on the peak direction of travel during these time periods. The results are addressed in Reference 8 and summarized below.
Overall, lowering the vehicle-occupancy requirement from 3+ to 2+ full time had a detrimental affect on the Busway. At the same time, significant improvements were not realized in the general-purpose freeway lanes. The major negative effects on the Busway and the neutral effects on the general-purpose lanes are highlighted below.
Peak hour travel speeds in the Busway were negatively effected during the 2+ demonstration. Travel speeds in the Busway declined from freeflow conditions at 65 mph to approximately 20 mph in the morning westbound direction. In the afternoon eastbound direction, travel speeds on the Busway decreased from 65 mph to 27 mph during the first month of the demonstration and then increased to 40 mph for the duration of the test.
A significant corresponding increase in travel speeds did not occur in the general-purpose lanes. Travel speeds in the morning westbound direction increased from 25 to 37 mph on the freeway lanes during the first month of the 2+ demonstration, but decreased to 23 mph for the remainder of the operation. In the afternoon, eastbound peak hour freeway travel speeds increased from 32 to 40 mph during the demonstration.
Travel speeds on both the Busway and the freeway lanes returned to close to pre-demonstration levels with the implementation of emergency legislation, AB 769, and the return to the 3+ occupancy requirement during weekday peak-periods. Travel speeds on the Busway increased to 45 mph in the morning and 55 mph in the afternoon peak hours. Although lower than the pre-demonstration 65 mph, both of these speeds represent generally freeflow conditions. Travel speeds in the general-purpose lanes were slightly lower than the pre-demonstration speeds at 20 mph and 28 mph for the morning and afternoon peak hours, respectively.
Examining these two measures together is important, as vehicle volumes may increase as the result of a change in the vehicle-occupancy requirement, but the total number of people being carried may decline or may increase at a much lower rate.
Buses have always been a key element of the El Monte Busway. Lowering the vehicle-occupancy requirement to 2+ had a significant effect on bus operations. The increase in the number of two-person carpools, which caused congestion on the Busway, resulted in lower bus operating speeds, longer bus travel times and reduced on-time performance, increased service overtime and operating costs, and increases in customer complaints. For example:
The changes in vehicle-occupancy levels significantly affected the violation rates on the Busway as shown below.
Time Period | ||
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Busway AM Peak-Period | Busway PM Peak-Period | |
Before January 2000 | 7% | 2% |
January 1 – July 24, 2000 | 1% | 1% |
Immediately after July 24, 2000 | 41% | 56% |
December 2001 | 4% | 9% |
The violation rates declined during the 2+ demonstration, as 2+ person carpools which would previously have been cited became authorized users. The violation rates increased significantly during the early phase of the 3+/2+ operations. Extra enforcement and more visible enforcement were not provided during the initial 3+/2+ operation. As a result, it appears that many 2+ carpools continued to use the lane during the 3+ peak-period. In response to concerns over these high violation rates, CHP undertook an aggressive enforcement program in January 2001. Elements of the program including briefings for all CHP shifts, press releases and radio broadcasts highlighting the correct occupancy requirements, announcing increased enforcement of the rules, and four weeks of enforcement saturation with extra offices assigned to the Busway. These efforts resulted in the violation rates returning to levels similar to those before the 2+ demonstration.
The I-15 FasTrak involved the conversion of an underutilized preexisting eight-mile 2-lane HOV facility to a peak-period reversible HOT. The project is sponsored by the San Diego Association of Governments (SANDAG), the local metropolitan planning organization (MPO), which has earmarked a significant portion of the revenues derived from the HOT lane to fund transit improvements in the I-15 corridor. Key operational attributes include (5):
The I-15 HOT lane initiative also included early and aggressive efforts to assess public opinion and potential usage of the lanes before the facility was launched. Additionally, the implementing agency SANDAG also has paid close attention to marketing issues throughout project implementation and operational phases. The SANDAG I-15 FasTrak Online website (http://argo.sandag.org/fastrak/library.html) provides full documentation of the supporting studies that were used to formulate tolling schedules, marketing plans and promotional materials.
Reference 5 provides additional details on the lessons learned form the I-15 HOT lanes, including:
1. HOV System Manual: NCHRP Report 414; National Academy Press; Washington D.C.; 1998
2. WSDOT Report on HOV Operations
3. Fuhs, Chuck and Jon Obenberger. HOV Facility Development: A Review of National Trends. Paper on the 2002 Transportation Research Board Annual Meeting CD ROM, January 2002.
4. Turnbull, K.F. Effective Use of Park-and-Ride Facilities. Synthesis of Highway Practice 213, National Cooperative Highway Research Program, Transportation Research Board, Washington, DC, 1995.
5. "A Guide for HOT Lane Development"; Perez, B. & Sciara, G.; FHWA; 2001
6. Turner, S. "Video-Based HOV Enforcement System To Be Tested," Urban Transportation Monitor. April 26, 1996, pp 3.
7. Billheimer, John, Moore, J.B., and Stamm, Heidi. HOV Marketing Manual – Marketing for Success, Federal Highway Administration, 1994
8. Turnbill, K.; "Affects of Changing HOV Lane Occupancy Requirements: El Monte Busway Case Study"; Texas Transportation Institute; FHWA-OP-03-002; June 2002
9. High Occupancy Vehicle Lanes Enforcement Survey. Prepared for Metropolitan Transit Authority of Harris County. Texas Transportation Institute, Texas A&M University System, College Station, TX, 1988.
10. Guide for the Design of High Occupancy Vehicle Facilities. American Association of State Highway and Transportation Officials. 1992.
11. Fuhs, C.A. High-Occupancy Vehicle Facilities: A Planning, Design, and Operation Manual. Parsons Brinckerhoff Quade & Douglas, Inc., 1990.