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Section 3: HOV Operator Survey and Interview Results

To understand the performance of HOV lane systems across the country, an initial survey of HOV lane operators was conducted in order to understand their goals, objectives, and current HOV lane performance based on monitoring efforts. The survey also explored policy changes that have been implemented or are planned to be implemented on HOV systems, as well as the reasons for making these changes and their impacts on lane performance. An online survey was developed and distributed to 74 HOV contacts across the country utilizing the Federal Highway Administration (FHWA) HOV Pooled Fund Study Database and other HOV resources including the Transportation Research Board (TRB) Committee on HOV Lanes and the Texas Transportation Institute, as well as networks of HOV professionals. The survey generated 28 responses representing 10 states and approximately 73 HOV facilities. The survey was supplemented with a review of existing data and follow-up conversations with additional HOV professionals and representatives of HOV operators.

Following the initial survey and literature review, in-depth one-on-one interviews were held with a subset of HOV operators who have experience in implementing various policy changes to discuss their experiences, challenges, and success factors. The objective was to understand how actual policy changes have impacted lane performance and under what conditions policy changes might be implemented in other areas to improve system performance. These discussions included representatives from Denver, Colorado; Houston, Texas; Minneapolis, Minnesota; Northern Virginia; San Diego, California; and the Puget Sound Region of Washington State.

Main findings from the survey and follow-up interviews are provided next.  These findings are grouped into the following subsections: System Goals and Objectives; Performance Monitoring; HOV System Performance; Plans to Revisit Goals; HOV Lane Operational Policies and Policy Changes; Policy Change Motivations; and Policy Implementation Success Factors.  The survey instrument and more detailed survey/interview comments are provided in a separate deliverable.

System Goals and Objectives

Respondents have indicated that while many HOV systems do not have officially adopted goals and objectives, most have goals and policies understood by operating and partner agencies and the urban areas of which they are part. Considerable similarity was found from one region to the next, incorporating six common objectives:

  • Maximizing person throughput;
  • Managing congestion by improving system efficiency;
  • Providing options for travel time savings and trip reliability;
  • Encouraging carpooling in peak periods;
  • Improving air quality; and
  • Supporting transit service and transit reliability.

Figure 3-1 summarizes survey responses relative to the goals and the intent of HOV systems. Some areas also note that the addition of HOV lanes was a means to add system capacity to accommodate regional growth under circumstances that will not permit the addition or expansion of general-use capacity. Others identify energy savings as an additional goal for their HOV systems.

Figure 3-1: Why did you add HOV lanes in your region? What are your HOV system goals?

Figure 3-1

Performance Monitoring

Eighty-two percent (82%) of survey respondents report that they monitor the performance of their HOV lanes. In most cases, the HOV lane operating agency is responsible for monitoring efforts. In some cases, partnerships with university research centers and third-party contractors or consultants are responsible for monitoring efforts. Performance criteria for HOV lanes most frequently include throughput (vehicular and/or person), travel time savings, and speed in the HOV lanes versus speed in the general-use lanes. Level of service is monitored almost as frequently. Other responses indicate the collection and analysis of data regarding accident rates, enforcement, transit performance and ridership trends, lane usage trends, and public opinion.

Performance measures and criteria generally relate to system goals and objectives. Therefore, systems identifying transit service as a priority, and/or are managed by a transit agency, may focus significant resources on monitoring transit-specific measures, while those who lack this focus do not. A measure such as public opinion has become increasingly important on systems where a pricing component (HOT lanes) has been implemented on a previously free HOV lane. Although most HOV systems do not specifically track public opinion, the monitoring of performance measures that clearly demonstrate a marked difference between the number of persons and vehicles in the HOV lanes versus the general-use lanes in an urban area, and the travel times and speeds in the HOV lanes versus the general-use lanes, have helped to generate public buy-in and support for lane operations in some urban areas. Effective communication of these measures can also be used to demonstrate that a policy change may be necessary to better utilize HOV assets in locations where they are not performing effectively.

Data collection methods vary from facility to facility and include both manual and automatic detection methods. Vehicle throughput (determined by traffic volume counts) and speed are typically collected through automatic detection devices such as traffic sensors and loop detectors. Person throughput and occupancy rates are determined through manual counts and visual survey. Enforcement data and violation rates are typically provided by the police or enforcement entity responsible for the HOV system. Travel time data collection frequently utilizes floating vehicle methods of collection by placing a transponder or GPS unit in cars or buses utilizing the HOV system. Other information, such as the number of hybrid vehicles that utilize an HOV system where this is permitted, may be collected from enforcement data, manual counts, or hybrid registrations (where applicable) to track their utilization of the system. This type of specialized information may not be regularly tracked, depending on available resources, but may be collected if there is a reason for the operating agency to investigate a particular type of system use that could impact a proposed policy change. Frequency of data collection is somewhat dependent on the method of collection and how often the operating agency queries automatic collection systems. Automatic measurement methods may be ongoing, while manual counts take place once or twice a year. Some agencies issue publicly available annual reports on system performance, while others have data available upon request.

On HOT systems emerging throughout the country, a greater emphasis has been placed on performance monitoring as resources, infrastructure, and technology that can be used for lane monitoring programs are considered in initial system design, and the advent of pricing raises the importance of accountability to the public regarding lane performance.

HOV System Performance

Seventy-five percent (75%) of survey respondents indicate that their HOV systems are achieving current performance objectives. Those who indicate otherwise cite issues resulting from congested lanes, such as too much demand during the peak period and resulting overcrowding issues, and low speed differential between HOV and general-use lanes. Other performance issues include lack of a continuous system, “end of the line” issues such as bottlenecks where HOV lanes reconnect with general-use lanes, high violation rates, and low usage during enforcement periods.

Underutilization, or “empty-lane syndrome,” is another common performance issue nationwide that has led to policy changes on HOV systems. Inadequate speed differential is also noted in some areas as it relates to geometric design, where a buffer separation results in lane friction between the HOV lane and the slower moving general-use lanes and impacts the HOV lane driver’s tendency to drive at free-flow speeds.

Plans to Revisit Goals

Of the 28 respondents, 21 have revisited or plan to revisit system goals based on changes since the initial implementation of their HOV system (see Figure 3-2). The two most frequent reasons for a policy change were cited as political interest and performance. Public opinion was the next most frequent motivation for revisiting goals, with other motivating factors including legislative changes, a desire for revenue, or a shift in regional goals or policies. Some facilities have changed goals based on a shift to HOT lanes, or due to a regional examination of pricing options. One respondent indicated that the goals were revisited due to the deterioration of transit speed and reliability.

High violation rates have also emerged in discussions with some HOV operators as necessitating the need for a policy shift that could enable better enforcement. One school of thought is that pricing may help to curb violation rates, as violators could buy in to the lane, generating a revenue stream and supporting increased infrastructure that in turn supports better enforcement activities. Infrastructure improvements could include improved lane configuration, implementation of enforcement technology, and increased presence of law enforcement.

Figure 3-2: Do you have plans to revisit / have you revisited the goals of your HOV system based on any of the following reasons?

Figure 3-2

HOV Lane Operational Policies and Policy Changes

There is wide variation in HOV lane operational policies across the country, which is largely dependent on system design and usage trends related to system goals, local politics (e.g., acceptance of toll lanes, carpool formation rates, air quality conformity, public support, transit ridership, legislative mandates), and the relationship of HOV lanes to the commute patterns of the traveling public. HOV operational limitations and performance issues have often been addressed by policy changes including occupancy requirements and hours of operation. The concept of managed lanes has further evolved to include vehicle eligibility, pricing, and access control as a viable means to impact overall lane performance and system efficiency.

Policy changes impacting hours of operation and occupancy requirements have been implemented and explored in many locations experiencing empty-lane syndrome as a means to improve utilization of the HOV system. Hours of operation have been reduced from 24-7 operations to weekday peak periods or daytime hours in some urban areas. This is typically due to political and public pressure for use of the lanes. In most cases, occupancy requirements have been decreased (e.g., from 3+ to 2+ or from 4+ to 3+) to relax carpool requirements and improve lane utilization. Increases in occupancy requirements have also been considered as a means to address lane overcrowding, and this has been successful in some areas such as Houston. At the same time, studies in other urban areas indicate that increases in occupancy requirements have resulted in sharp drops in lane usage and additional congestion in the general-use lanes. For this reason, many areas now view pricing as a better option to manage lane congestion.

Conversion to or from general-purpose lanes has frequently been part of the HOV conversation. Many regions report constant public and political pressure to convert HOV capacity to general use, despite results indicating positive HOV performance. In Vancouver, Washington, design issues including a lack of connections to other HOV facilities and connections to park and ride resulted in conversion of HOV lanes to general-purpose lanes after a pilot project even with performance results indicating positive lane performance. “Take away” of a general-use lane for conversion to a managed lane is not a politically popular concept. Nevertheless, many departments of transportation (DOTs) across the country are including this option as part of the discussion. In concert with pricing, managed lanes may help to address current or future transportation funding shortfalls for urban areas.

Access changes have been common on existing systems over the years. Access and/or egress locations may be added or shifted due to public support, safety concerns, or in response to changing congestion levels that may impact lane performance. Access changes have typically been implemented in design situations where striping or moveable barriers can easily be shifted.

Figure 3-3: Have any of the following policy changes been applied / are you considering any of the following changes to your original HOV System?

Figure 3-3

Survey results indicate that pricing is currently explored most frequently among respondents as a potential policy change (see Figure 3-3 above). Pricing is viewed as a potential solution for a spectrum of issues—potentially addressing unused HOV capacity in the peak period and the need for better lane management in congested conditions and providing needed revenue. Systems with a transit-oriented focus believe pricing can help directly impact transit trip times that are potentially degraded on congested HOV lanes. Pricing also offers a better performance management option for some regions because of the impacts that solutions such as an occupancy requirement change alone may have on the general-purpose lanes. Pricing is packaged with at least one additional policy change—most frequently, vehicle eligibility to allow SOVs into the lane. Pricing also has benefits that could potentially address HOV enforcement concerns in areas with extremely high violation rates that impact lane performance.

Vehicle eligibility was also identified as a frequently implemented policy change. HOV lane eligibility has most frequently been expanded to allow motorcycles and hybrid vehicles into the lanes. In some areas, lanes initially designated as bus-only or transit-only have been expanded to include HOVs. The issue of hybrid and alternative fuel vehicle eligibility varies by state and has been handled in a variety of ways. Many systems permitting these vehicles did so prior to the mass market availability of hybrids. Given hybrid availability and rising fuel prices, allowing these vehicles has had a significant impact on HOV lane conditions in recent years, particularly in locations where lanes are already congested in peak periods. Hybrids may also have a significant impact on revenue on systems that have converted or are considering a conversion to HOT. Pressure from politicians in some states impedes lane operators from excluding hybrid vehicles from managed lanes, even in congested situations. The compromise has been to cap the numbers of hybrid vehicles eligible for lane usage through vehicle registration or permitting programs. For HOT lane systems, operators have issued a limited number of transponders to hybrid users through a lottery or registration process. HOV systems attempting to cap hybrid usage, such as in Virginia, initiated a date cutoff tied to vehicle registration and issue a special license plate to permitted hybrid users.

Policy Change Motivations

Follow-up interviews with survey respondents revealed motivations for previously implemented policy changes on HOV lanes. These previous policy changes ranged from occupancy restrictions and hours of operation to the implementation of tolling for otherwise ineligible vehicles (e.g., SOVs). The original motivation for past policy changes varied, but a few common themes emerged from the interviews. Empty-lane syndrome was the single most frequent motivation for conversion of HOV lanes to HOT lanes. In these cases, the HOV lanes were underutilized, and public desire was for HOV lanes to be returned to general-use lanes. To retain benefits for carpoolers, while addressing the perception of underutilized HOV lanes, the agencies proposed pricing as a means to increase vehicle throughput in both HOV and general-use lanes. Pricing of SOVs provides a more flexible option for managing lane volume. By varying the SOV (“buy-in”) toll rates in the HOT lanes, an agency can attract enough vehicles to fill the lanes while still avoiding congestion from too much demand. A parallel motivation for shifting HOV to HOT is the desire for new revenue.

Many DOTs cannot afford to adequately maintain, improve, or expand their current systems without additional revenue or without help from private sector resources. Public-private partnership initiatives have emerged as a new funding mechanism for managed-lanes projects and are based upon the premise that there will be a return on investment for the private sector. Revenue generated from priced lanes makes this type of funding mechanism possible. In some states, priced lanes are currently viewed as the only mechanism for future freeway capacity expansion, given limited resources and regional transportation goals and policies.

Some responding agencies have also made changes to occupancy restrictions, eligibility restrictions, and hours of operation. Conversion from an occupancy policy of 2+ to that of 3+ (or even 4+) is typically in response to peak period congestion. Some agencies apply this increased restriction for the entire period of HOV operation, while others just apply the change in the peak hour, with the original occupancy restriction in the off-peak. Examples also exist where the responsible agency originally made the occupancy requirement too restrictive. There are instances where 3+ or 4+ policies have been changed to 2+ or 3+ due to lack of use. Indeed, there are even a couple of examples of HOV 2+ lanes being converted back to general use for the same reason. Vehicle eligibility is another change category that HOV operators have leveraged. In the last several years, there has been particular interest in allowing low-emission and/or hybrid vehicles in HOV lanes, regardless of the number of persons inside. Federal law (SAFETEA-LU) currently allows this, and some states have taken steps to implement this policy change. HOV operators have also changed the hours of operation of their facilities. For those facilities that are not restricted all 24 hours of the day, operating hours can be changed to best serve the travel market. For example, peak spreading could lead to congestion in the corridor at times when the HOV lane is open to all traffic. By expanding the hours of operation, the advantage of increased travel speeds can be preserved for carpoolers.

Table 3-1 summarizes the anticipated performance impacts of potential policy changes based on the operating conditions in an HOV lane.

Table 3-1: HOV Conditions and Potential Policy Changes
HOV Lane Condition Policy Change Anticipated Result
Underutilized Occupancy policy decrease Increased volumes in the HOV lane and shift from general-use lanes due to relaxed restrictions.
Hours of operation change Increased daily volumes in the HOV lane and shift from general-use lanes due to relaxed restrictions.
Vehicle eligibility
  1. Hybrid
  2. Transit
  3. Motorcycle
Increased volumes in the HOV lane and shift from general-use lanes due to relaxed restrictions.
Pricing Increased volumes in the HOV lane and shift from general-use lanes, particularly during peak periods when SOV drivers can pay for a guaranteed travel time. Revenue stream generated from paying SOV drivers. Positive impact on general-use lanes due to volume shift during peak period.
Conversion to GP lane Increased lane volume due to the removal of lane restrictions. Decreased person and vehicular throughput, and degraded transit trip times can be anticipated for the corridor due to lack of demand management and lack of travel time incentives to carpoolers and transit users.
Access changes Increased volumes in the HOV lane and shift from the general-use lanes if access/egress better reflects peak period commute patterns or is easier for the public to understand and utilize.
Congested Occupancy policy increase Decreased volumes in the HOV lane and shift to the general-use lanes due to increased restrictions. Potential for negative impact on general-use lanes if there is a sharp decrease in carpools meeting new requirements.
Vehicle eligibility
  1. Hybrid
  2. Transit
  3. Motorcycle
Decreased volumes in the HOV lane and shift to the general-use lanes due to increased restrictions. Increased restrictions on hybrid vehicles are most likely to impact lane performance but can be controlled through registration caps and permitting.
Pricing Free-flow volumes maintained in the lane during hours of operation due to active lane management, particularly during peak periods. Revenue stream generated from paying SOV drivers. Guaranteed travel times on priced lanes during peak periods also provides benefits to carpoolers and transit users.
Add or convert a lane Increased person and vehicular throughput and improved travel times due to an extra lane of managed capacity. Potential for negative impact on general-use lanes if there is a lane takeaway.
High violation rate / Incorrect utilization Pricing Improved monitoring on the HOV lanes due to enhanced infrastructure. Revenue stream generated from paying SOV drivers can help to support monitoring efforts.
Access changes More restrictive access will curb tendencies for ineligible drivers to enter the lane. Access changes can include separation changes (i.e., stripe vs. buffer vs. pylon) or ingress/egress location changes

Degraded transit trip times

Pricing Free-flow volumes maintained in the lane during hours of operation due to active lane management, particularly during peak periods, supports transit trip reliability. Revenue stream generated from paying SOV drivers can support transit operations. Guaranteed travel times on priced lanes during peak periods provide benefits to transit users and could increase transit ridership.

Vehicle eligibility

  1. Hybrid
  2. Motorcycle

Decreased volumes in the HOV lane and shift to the general-use lanes due to increased restrictions. Increased restrictions on hybrid vehicles are most likely to impact lane performance but can be controlled through registration caps and permitting.

Add or convert a lane Improved transit travel times due to an extra lane of managed capacity. Additional lane could be reserved for transit-only usage or transit and carpool usage for additional travel-time reliability. Potential for negative impact on general use lanes if there is a lane takeaway.

Policy Implementation Success Factors

While lane performance is a central factor in the decision for HOV policy change and the key to understanding the system impacts of one policy over another, there are many other factors that influence the successful implementation of a policy change. Changes such as hours of operation, vehicle eligibility, and occupancy may in some circumstances be policy changes within the authority of the facility operator, or they may require legislative action, depending on the institutional arrangements and laws in a particular location. Authorized policy changes are of course a quicker path to implementation, as they do not require the formal actions of elected legislators. Some agencies acknowledged preferences for not opening up legislative issues, but rather to work with factors within their control. Opening up legislation can lead to unexpected outcomes and slow response to the operating issues faced. Some HOV operators have appointed boards designated to make policy decisions regarding HOV systems. This institutional arrangement can facilitate the HOV policy decision-making process, particularly when multiple partnering agencies are involved. Along these same lines, many operators comment that specific Federal rules related to HOV policy changes and lane performance actually facilitate implementation at the local level.

Some states still require enabling legislation for HOV policy changes. There are many examples of policy changes that have been made due to the political will of legislators or other local leaders, and there are at least as many that have failed due to the lack of a political champion. In particular, all HOT lane operators across the country indicate that political support and a political champion was a key in overcoming potential implementation hurdles for HOT lanes. It typically has taken years of education and persuasion to cultivate political leaders and agency partners to implement HOT pricing on existing HOV lanes. Effective interagency coordination and clear ownership of designated roles and responsibilities is another commonality across systems that have successfully implemented HOT lanes. Research studies and data that validate the need for this type of policy change are also critical tools to support these decisions.

Transportation agencies exploring pricing have also learned that not all HOV lanes are good candidates to be HOT lanes. Many lanes that meet the performance “rules of thumb” for conversion are constrained corridors with no space for tolling systems without costly design overhauls and acquisition of additional rights-of-way. The HOT facilities currently in operation are regarded as “low hanging fruit” relative to other facilities under study for conversion.

Recent experience has been promising. Operating agencies have made progress with the support of US DOT grant programs such as the Urban Partnership Agreement (UPA) and the Value Pricing Pilot Program (VPPP). Corridors have been carefully selected for implementation considering factors that promote a high likelihood for success.

Typical success factors include favorable geometrics and access locations, reasonable potential for public acceptance, a political champion, clear roles and responsibilities between agencies, and strong interest from the transit operator. In general, agencies proposing candidate facilities for conversion experience 20 percent or more of unused capacity in the peak period, and have the staff and financial resources to plan, design, implement, and operate the HOT facility. The lack of some of these factors [1] is a principle reason given for abandoned efforts in the past.

Federal assistance in rule-setting would be helpful in some areas, such as in rules and guidance for setting minimum occupancy and eligibility policies. For example, in conditions where occupancy policy must increase to 3+ to address congestion, but hybrid vehicles are still allowed in the lanes, this seems counterintuitive to many in the HOV/HOT community.

[1] Or the need for too many design exceptions and compromises to overcome right-of-way limitations and other geometric design problems


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December 2008

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