High-occupancy Vehicle Research Articles

Converting a Large Region to a Multimodal Pulsed-Hub Public Transport Network

Applicability of the cost-effective strategy used in Switzerland that successfully integrates all public transport for the entire country into a multi-hub timed-transfer system (pulsed-hub network) is investigated using the greater San Francisco Bay Area as an illustrative case study. For the existing and proposed Bay Area rail service routes, the study investigates the optimal repeating (clock-face) base headway for the pulsed-hub network, hub spacing, and locations (ideally adjacent to dense and diverse land uses providing destinations within walking distance, preferably a downtown), and hub station design to minimize transfer walk times. A pulsed-hub network schedule, because of the repeating schedule, can be shown as a schedule map that represents typically a 1-h schedule module. The schedule map, showing the routing and travel times between hubs and the pulse timings by means of a clock face at each hub, becomes a tool to develop the multihub system and to communicate with all stakeholders, including policy makers and the public. The illustrative pulsed-hub network uses existing and proposed rail services and express buses on high-occupancy vehicle lanes. These include the two publicly owned regional rail systems, Bay Area Rapid Transit and the Peninsula Commute Service (Caltrain); the intercity Amtrak-operated Capitol Corridor trains between San Jose, Oakland, and Sacramento (assuming that reliable passenger service can be maintained by freight railway by providing schedule windows for both passenger and freight trains); the proposed Sonoma-Marin Area Rail Transit and Dumbarton Rail Bridge routes; and the proposed California high-speed trains, currently in environmental review.

THE AUSTRIAN HOV-LANE—EXPERIENCES IN IMPLEMENTATION AND OPERATION

The ever increasing use of private vehicles for daily commuting trips contributes to a rising level of congestion in metropolitan areas. The trip times for each driver grow constantly. Just this situation is approaching Linz (ca 200 000 inhabitants), which is the capital of Upper Austria and also the political and economical centre of the region. At one every workday morning heavily congested arterial road towards the city, since 1998 high occupancy vehicles (HOV) with 3 or more occupants (3+) have been permitted to use the existing bus lane too. The opportunity to save time should encourage commuters to share their cars and should result in a more efficient car use. Based on a study, by which the efficiency of that first HOV-lane in Austria was investigated, the effects and the influences on the trip duration, commuting behaviour, drivers attitudes towards the measure, bus drivers' and policemen's experiences as well as the environmental and public costs are described. Additionally, some imperfections are revealed concerning, for instance, the used traffic signs. As the main outcome the implementation of this HOV-lane proves to be a practical approach for improving the bad commuting traffic situation on a local level. However, it must be seen only as one of many measures that would be necessary to create a real sustainable solution for the whole metropolitan area.

INTERMODALISM—A SOLUTION FOR HIGHWAY CONGESTION AT THE MILLENNIUM?

ABSTRACTHighway congestion in the Northeastern U.S. is increasing beyond practical ability to obtain relief by the construction of added lanes. Single mode solutions, including HOV lanes and transit, have failed to significantly mitigate problems of highway congestion. Traditional and innovative public transportation modes using intermodal centers and enhanced transfer facilities are discussed as solutions for the congestion. Efforts in Connecticut, including projects in New Haven, Norwalk, Hartford, and New Britain are examined to show the need for coordinated transportation services that provide seamless trip options for users.

Disappearing traffic? The story so far

Reallocating roadspace from general traffic, to improve conditions for pedestrians or cyclists or buses or on-street light rail or other high-occupancy vehicles, is often predicted to cause major traffic problems on neighbouring streets. This paper reports on two phases of research, resulting in the examination of over 70 case studies of roadspace reallocation from eleven countries, and the collation of opinions from over 200 transport professionals worldwide. The findings suggest that predictions of traffic problems are often unnecessarily alarmist, and that, given appropriate local circumstances, significant reductions in overall traffic levels can occur, with people making a far wider range of behavioural responses than has traditionally been assumed. Follow-up work has also highlighted the importance of managing how schemes are perceived by the public and reported in the media, with various lessons for avoiding problems. Finally, the findings highlight that well-designed schemes to reallocate roadspace can often contribute to a multiplicity of different policy aims and objectives.

Disappearing traffic? The story so far

Reallocating roadspace from general traffic, to improve conditions for pedestrians or cyclists or buses or on-street light rail or other high-occupancy vehicles, is often predicted to cause major traffic problems on neighbouring streets. This paper reports on two phases of research, resulting in the examination of over 70 case studies of roadspace reallocation from eleven countries, and the collation of opinions from over 200 transport professionals worldwide. The findings suggest that predictions of traffic problems are often unnecessarily alarmist, and that, given appropriate local circumstances, significant reductions in overall traffic levels can occur, with people making a far wider range of behavioural responses than has traditionally been assumed. Follow-up work has also highlighted the importance of managing how schemes are perceived by the public and reported in the media, with various lessons for avoiding problems. Finally, the findings highlight that well-designed schemes to reallocate roadspace can often contribute to a multiplicity of different policy aims and objectives.

THE AUSTRIAN HOV-LANE—EXPERIENCES IN IMPLEMENTATION AND OPERATION

The ever increasing use of private vehicles for daily commuting trips contributes to a rising level of congestion in metropolitan areas. The trip times for each driver grow constantly. Just this situation is approaching Linz (ca 200 000 inhabitants), which is the capital of Upper Austria and also the political and economical centre of the region. At one every workday morning heavily congested arterial road towards the city, since 1998 high occupancy vehicles (HOV) with 3 or more occupants (3+) have been permitted to use the existing bus lane too. The opportunity to save time should encourage commuters to share their cars and should result in a more efficient car use. Based on a study, by which the efficiency of that first HOV-lane in Austria was investigated, the effects and the influences on the trip duration, commuting behaviour, drivers attitudes towards the measure, bus drivers' and policemen's experiences as well as the environmental and public costs are described. Additionally, some imperfections are revealed concerning, for instance, the used traffic signs. As the main outcome the implementation of this HOV-lane proves to be a practical approach for improving the bad commuting traffic situation on a local level. However, it must be seen only as one of many measures that would be necessary to create a real sustainable solution for the whole metropolitan area. Frist Published Online: 30 Jul 2012

Travel Demand Modeling and Conformity Determination: Atlanta Regional Commission Case Study

The Atlanta Regional Commission (ARC) regional travel demand model is described as it relates to its link-based emissions postprocessor. In addition to conformity determination, an overview of other elements is given. The transit networks include the walk and highway access links. Trip generation addresses trip production, trip attraction, reconciliation of productions and attractions, and special adjustments made for Hartsfield Atlanta International Airport. Trip distribution includes the application of the composite impedance variable. In the mode choice model, home-based work uses a logit function, whereas nonwork uses information from the home-based work to estimate modal shares. Traffic assignment includes preparation of time-of-day assignments. The model assigns single-occupancy vehicles, high-occupancy vehicles, and trucks by using separate trip tables. The procedures can accept or prohibit each of the three types of vehicles from each highway lane. Feedback between the land use model and the traffic model is accounted for via composite impedances generated by the traffic model and is a primary input to the land use model DRAM/EMPAL. The land use model is based on census tract geography, whereas the travel demand model is based on traffic analysis zones that are subareas within census tracts. The ARC model has extended the state of the practice by using the log sum variable from mode choice as the impedance measure rather than the standard highway time. This change means that the model is sensitive not only to highway travel time but also to highway and transit costs.

Development of High-Occupancy Vehicle Facilities: Review of National Trends

High-occupancy vehicle (HOV) lanes have existed for more than 30 years. As a congestion management strategy, HOV lanes have been widely applied in the United States to preserve mobility, maintain trip reliability, and improve the person-moving capability within a corridor or metropolitan area. Although there are many examples of successful HOV lanes that carry large numbers of commuters and buses, criticism has been levied toward HOV lanes in some metropolitan areas. A lack of information and data about the benefits of HOV lanes, the nationwide trend toward less carpool use, and the closure of two projects in New Jersey in 1998 have resulted in reassessment of the purpose, role, and benefits of HOV lanes by some metropolitan areas and agencies. This has led some to postulate that the HOV lane concept may no longer be viable. In response to these perceptions, available data are reviewed and some perspectives are provided on the recent past and possible future of HOV lanes, particularly the treatments applied on urban freeways that represent the majority of such applications. A summary of recent experiences, growth, type, and changes that have occurred with HOV lane operational policies is presented. Many of these trends have been influenced by federal legislation over the last 15 years, specifically the Clean Air Act and operational policies related to the development of HOV lanes as a congestion management strategy. Trends in future HOV lane development, based on the current roadway improvement plans of various states, are presented to provide a prospective for future policy and programming considerations.

San Diego’s Interstate 15 Congestion Pricing Project: Traffic-Related Issues

Traffic-related findings from the evaluation of the Interstate 15 (I-15) congestion pricing project are summarized. The project was a 3-year demonstration that allowed single-occupant vehicles (SOVs) to use the existing I-15 high-occupancy-vehicle (HOV) lanes, known as the I-15 express lanes, for a fee. San Diego State University conducted an independent, multielement evaluation of the I-15 pricing project to assess its impacts for both the ExpressPass and FasTrak phases of this demonstration. The primary project goals were ( a) to maximize use of the existing I-15 express lanes, ( b) to test whether allowing solo drivers to use the express lanes’ excess capacity could help relieve congestion on the I-15 main lanes, ( c) to fund new transit and HOV improvements in the I-15 corridor, and ( d) to use a market-based approach to set tolls. At the end of 1999, the I-15 pricing project was meeting its primary objectives. There was substantially better utilization of the express lanes. Both ExpressPass and FasTrak were feasible solutions for generating sufficient revenue to fund the new express bus service, called Inland Breeze. Neither ExpressPass nor FasTrak negatively affected carpool volumes on the express lanes; FasTrak was able to redistribute volumes from the middle of the peak to the peak shoulders. Free-flow conditions were maintained at virtually all times. The project’s primary benefit was the reliability of ontime arrival for users. The project was also able to slightly alleviate congestion on the I-15 main lanes. SOV violation rates in the I-15 express lanes remained substantially below the preproject level. Also discussed are the air quality, delay, and park-and-ride impacts of the project.

Optimal Setback Planning and Delay Analysisfor HOV Lanes

To maximize the potential for success of an urban high-occupancy vehicle (HOV) lane, there are several design intricacies that require special attention, particularly at critical intersections. This paper is based on extensive research of HOV lanes, specifically their optimal setback planning and the resulting impact on delay, that was conducted recently in Israel. A setback, the termination of an HOV lane prior to a critical intersection—typically characterized by long delays and diverging queues—allows passenger vehicles, in addition to buses, to use the HOV lane. Throughput capacity is thus increased and delay for passenger vehicles reduced at the critical intersection, especially when the HOV lane is not utilized to its fullest capacity. The paper also presents the geometry of a setback, with and without a right-turn lane and, in addition, introduces the development of a model for determining the optimal length of a setback. Average delay to HOV vehicles and to non-HOV vehicles is given as a function of the degree of saturation for a design that both includes and does not include a setback. At critical intersections, the provision of an HOV lane with an optimal setback is shown to result in the least amount of total passenger delay.

Evaluating commuter opinion of congestion pricing in metropolitan Seattle

AbstractContinued growth and development in the Puget Sound region combined with existing geographic limitations have resulted in a transportation network that is at or near capacity for many hours during every weekday. Single‐occupancy vehicles (SOVs) remain the predominant mode of travel, despite a network of high‐occupancy vehicle lanes and regional transit. Given this situation, considering alternative methods to regulate traffic flow is necessary, and the implementation of a regional congestion pricing system is one such option. Although widespread throughout the world, congestion pricing has only recently been implemented in the United States.

High-occupancy/toll lanes: where should they be implemented?

Since the first high-occupancy toll (HOT) lane was implemented in Orange County, California in 1995 there has been an increasing interest in such lanes as a means to reduce congestion, increase utilization of underutilized high-occupancy vehicle (HOV) lanes, and generate revenue. In order to determine where such lanes are appropriate, a model is constructed to estimate how adding an HOV lane, an HOT lane or a mixed flow lane to an existing freeway affects delay in various circumstances. Except when the initial delay is very high, adding a mixed flow lane is more effective in reducing delay than adding either an HOV or HOT lane, and it costs less. If both the initial delay and the initial proportion of HOVs are very high, then adding an HOV lane is more effective in reducing delay than adding either a mixed flow or HOT lane. But if the initial delay is high and the initial proportion of HOVs is not high an HOT lane is the most effective in reducing delay. Adding an HOT lane should also be considered if substantial growth in traffic is expected, because HOT lanes perform relatively well in terms of reducing delay across all levels of initial delay and HOV usage. However, because HOT lanes are considerably more costly to construct and operate than mixed flow or HOV lanes, the revenue generating potential must also be assessed, and the savings in delay must be sufficient to justify the additional cost. The revenue generating capacity of HOT lanes is low when the initial delay is low, and in such cases alternate methods of utilizing the HOT lane initially might be desirable.

Automotive Emissions in Developing Countries: Traffic Management and Technological Control Measures

Urbanization in developing countries is causing an increase in roadside air pollution, which is associated with adverse environmental impacts. Such impacts are most prevalent in densely overpopulated urban centers, creating the need for mitigation strategies. In developed countries, traffic and environmental policy planners are relying on stringent regulations, advanced tailpipe emission-reduction technologies, and complex traffic control measures (such as high-occupancy vehicles restricted lanes, bus-dedicated lanes, park-and-ride facilities, dynamic traffic light signalization, and hot-spot management) to mitigate excess automotive emissions. In contrast, developing countries may require only conventional or traditional traffic control measures (such as truck rerouting, car pooling, and promoting mass transit) along with affordable simple technological solutions to reduce automotive emissions to acceptable levels, at least in the short term, because of differences in traffic fleet characteristics and tr...

Reallocating road space to buses and high occupancy vehicles in Leeds

Securing the most efficient use of existing road space to maximise the efficient and sustainable movement of people and goods has emerged as one of the key issues for urban transport planners. For over ten years Leeds has been implementing an integrated transport strategy, a central part of which is to secure greater efficiency from the existing road network. This paper outlines these policies and focuses on the practical aspects of reallocating road space and traffic capacity by reference to three different projects in Leeds. The measures discussed cover traffic management in the city centre and priority issues on major radial corridors, including the various approaches being adopted within a ‘quality bus initiative’ on a busy radial corridor. The example of the pioneering A647 scheme is used to show how high occupancy vehicle (HOV) lanes can not only assist public transport but also benefit motorists.

Reallocating road space to buses and high occupancy vehicles in Leeds

Securing the most efficient use of existing road space to maximise the efficient and sustainable movement of people and goods has emerged as one of the key issues for urban transport planners. For over ten years Leeds has been implementing an integrated transport strategy, a central part of which is to secure greater efficiency from the existing road network. This paper outlines these policies and focuses on the practical aspects of reallocating road space and traffic capacity by reference to three different projects in Leeds. The measures discussed cover traffic management in the city centre and priority issues on major radial corridors, including the various approaches being adopted within a ‘quality bus initiative’ on a busy radial corridor. The example of the pioneering A647 scheme is used to show how high occupancy vehicle (HOV) lanes can not only assist public transport but also benefit motorists.

Efficiency Gains from Value Pricing: Case Study of Sunol Grade

A case study of value pricing of a proposed capacity expansion for a major congested corridor in the San Francisco Bay Area known as the Sunol Grade is presented. A new high-occupancy vehicle (HOV) lane with a two-passenger-plus occupancy requirement is proposed to be added to the existing three southbound lanes to serve the morning peak period. The performance of the proposed HOV lane is compared with that of a value-priced express lane, which would provide unlimited, free access to vehicles with three-plus occupants and priced access to lower-occupancy vehicles. Compared with the proposed HOV lane, the express lane would reduce total vehicle-hours of delay—on both the general purpose and new lanes—by approximately two-thirds during the morning peak period, according to the queuing and high-occupancy mode-share models used here. These results are due to efficient throughout and increases in HOV mode share, made possible by the free-flowing conditions in the express lane compared with the expected congestion in a two-passenger-plus HOV lane.

Simulated Travel Impacts of High-Occupancy Vehicle Lane Conversion Alternatives

A simulation model of a hypothetical highway corridor was used to analyze the effects of converting an existing high-occupancy vehicle (HOV) lane to either a high-occupancy toll (HOT) lane or a mixedflow lane. The simulation model, which uses a nested logit structure with a synthetic sample of individuals, estimates vehicle miles of travel (VMT), vehicle hours of travel, and person hours of travel in the corridor. The analysis suggests that mobility needs can best be served by using excess HOV lane capacity as an HOT lane facility. Capacity expansion alternatives are also analyzed, including adding mixed-flow travel lanes or converting existing lanes to HOV or HOT lanes. Alternative toll levels are also simulated. Results show that managing capacity as an HOT or HOV lane could provide superior mobility benefits with a net decrease in VMT if capacity must be expanded.

Dynamic Trip Assignment-Simulation Model for Intermodal Transportation Networks

A dynamic trip assignment-simulation model for urban intermodal transportation networks is presented. The model considers different travel modes, such as private cars, buses, metro-subway, and high-occupancy vehicles. The model captures the interaction between mode choice and traffic assignment under different information provision strategies. It implements a multiobjective assignment procedure in which travelers choose their modes and routes based on a range of evaluation criteria. The model assumes a stochastically diverse set of travelers in terms of their relevant choice criteria and access and response to the supplied information. The model overcomes many of the known limitations of static tools used in current practice. These limitations relate to the types of alternative measures that may be presented and evaluated and to the policy questions that planning agencies are increasingly asked to address.

Comparisons from Sacramento Model Test Bed

Three land use and transport interaction models were applied to the Sacramento, California, region by various teams of researchers. The results of these efforts were compared with each other and with the traditional transport demand model used by the regional government. The results of the modeling efforts are compared, with the focus being on how the design of the modeling frameworks and their application influenced the modeling results. A trend scenario was compared with three different policy scenarios: one that involved high-occupancy vehicle (HOV) lane construction, one that added beltway construction as well as HOV construction, and a third that involved light rail construction and limited pricing of automobile use. The results differ among the different models for the trend scenario, as well as for each model with respect to scenario-to-trend comparisons. The results show some of the limitations of aggregate models calibrated to cross-sectional data. The differences between the models provide important insight into how models should be calibrated and how their results should be used. Uncertainty in land use transport interaction models seems inevitable, and further research should investigate how such modeling frameworks should best be used to understand the influence of policy in the face of uncertain futures.

Methodology for Assessing High-Occupancy Toll-Lane Usage and Network Performance

A modeling framework for the evaluation of high-occupancy toll (HOT) facilities is discussed. It is based on a traffic simulation-assignment model interfaced with an unordered multinomial logit mode-choice model. The model allows for the prediction of high-occupancy, transit, and single-occupancy vehicle modal shares, based on prevailing traffic conditions and tolls. Also presented is an illustrative investigation of the sensitivity to various elements of the modal-choice function using the methodology and of the effect of different HOT facility features on HOT lane usage and associated system performance. These features include HOT lane configurations, pricing levels, carpooling attractiveness, changing departure times, and sensitivity to generalized cost. A representation of the south-central part of I-35W and the supporting roadways in the Fort Worth, Texas, area was used in the study. The results of the simulations were analyzed under each of the operating and behavior characteristics to evaluate the potential success of an HOT facility. Improving the carpooling attractiveness decreases the number of vehicles on the roadway but may not necessarily improve the average travel time for the system as a whole. The larger the departure-time window, the easier it is for travelers to carpool; however, the relatively small number of people choosing the HOV mode may inhibit the average travel time for the system from reflecting the impacts of the reduced vehicle trips. Increasing the sensitivity to time, or generalized cost, raises the HOV mode share when there is an HOT facility available.