Lane Operations Research Articles

Interpretations of Downs–Thomson paradox with median bus lane operations

The Seoul Metropolitan Government has implemented a public transportation priority policy with the introduction of a 121.1 km long of the Median Bus Lane (MBL). Therefore, to analyze the impacts of the introduction of Jongro-gu MBL in January 2018, an effect analysis using the speed and volume of passenger cars and buses in Seoul is conducted in this study. The interpretation of the Downs-Thomson (D-T) paradox demonstrates that the reduction in passenger car mode capacity can increase total social benefits. This study shows that the speeds of passenger cars and buses have reached the deterministic user equilibrium after the MBL introduction, resulting in an increase in total social benefits. Moreover, it demonstrates that the bus priority policies, which gives the right to keep the capacity of buses guaranteed in urban areas, will be effective. The interpretation of the D-T paradox will contribute to the formulation of transport demand management policies.

Comparing Route Choice Models for Managed Lane Networks with Multiple Entrances and Exits

Developing an appropriate route choice model for managed lanes with multiple entrances and exits is critical for the success of managed lane planning and operations. This research focuses on route choice models for managed lane networks with stochastic and time-varying tolls and travel times. In the model, a traveler receives real-time information about the tolls and travel times upon arrival at each diverge node and makes a dynamic lane choice decision that minimizes the total expected cost. The online route choice model is formulated as a Markov decision process and solved using a backward recursion algorithm. The model is compared against four other routing models: a binary logit model, a model based on decision routes, a model that chooses paths a priori, and a model with routes chosen randomly. The study also models irrational driver behavior with parameters like driver’s inclination toward making optimal lane choices and preference for certain lanes. Findings show that the expected costs from the routes chosen using the decision route model from the literature are close to the optimal cost with an average percentage error of 0.93%. The binary logit model is shown to have a high average error of 50% in the expected cost when a driver is assumed to behave rationally, but the same model shows optimal prediction for certain irrational driver behaviors. The proposed routing model forms a basis for future work in the area of managed lane pricing and planning.

Dynamic Control of Climbing Lane on Expressways

Travel time on an expressway segment with a climbing lane may be affected by the appearance of slow-moving vehicles such as trucks. If slow-moving vehicles do not use the climbing lane, the traffic stream on the segment may worsen. In addition, forced lane changes to avoid such slow-moving vehicles lead to a significant threat of traffic accidents. The efficient operation of climbing lanes in terms of mobility and safety is one of the challenges faced by traffic engineers. The Korea Expressway Corporation suspends the operation of climbing lanes in an attempt to improve mobility and safety during high traffic demand periods such as national holidays and vacation seasons. Against this background, a methodology for the dynamic control of climbing lane operations based on realtime traffic conditions was developed in this research. The proposed method was evaluated using Vissim. The simulation results showed that the dynamic control of a climbing lane based on real-time traffic status improved mobility and safety by increasing the average travel speed by up to 15.6% and reducing the average delay and number of conflicts at the merging segment by up to 30.6% and 62.1%, respectively.

교통안전성을 고려한 고속도로 오르막차로 동적운영 알고리즘 개발

본 연구는 다양한 교통상황에서의 오르막차로의 안전성 측면을 고려하여 운영기준 수립 및 운영 알고리즘을 개발하고자 하였다. 교통량과 중차량 비율에 따른 시나리오를 설정하고, 미시적 교통류 시뮬레이션으로 구현하여 분석을 수행하였으며, 오르막차로 개폐여부에 따른 안전성을 평가하였다. 안전성을 평가하기 위하여 교통상충건수와 상충심각도를 평가지표(SSM:Surrogate Safety Measure)로 사용하였다. 분석결과, 서비스 수준이 낮고 중차량 비율이 증가할수록 교통상충건수가 증가하였으며, 서비스수준이 높고 중차량 비율이 증가할수록 상충 심각도가 높아짐을 보였다. 이를 바탕으로 교통 안전성 측면을 고려한 오르막차로 개 폐 기준 및 탄력적 운영을 위한 알고리즘을 제시하였다. 본 연구결과를 활용할 경우, 기존의 운영효율성 측면과 안전성측면 동시에 고려할 수 있는 효율적인 오르막차로 운영이 가능할 것이며, 교통사고 감소 효과도 기대할 수 있을 것이다. 또한 갓길차로, 공사구간관리 등 LCS 운영시 안전성 측면을 고려한 전략적 운영을 지원할 수 있을 것이다. Interest in freeway truck traffic has increased largely due to greater safety concerns regarding truck-related crashes. The negative interactions between slow-moving trucks and other vehicles are a primary cause of hazardous conditions, which lead to crashes with larger speed variations. To improve operational efficiency and safety, providing a climbing lane that separates slow-moving trucks from higher performance vehicles is frequently considered when upgrading geometrics. This study developed an operations strategy for freeway climbing lanes based on traffic conditions in real time. To consider traffic safety when designing a dynamic strategy to determine whether a climbing lane is closed or open, various factors, including the level of service (LOS) and the percentage of trucks, are investigated through microscopic simulations. A microscopic traffic simulator, VISSIM, was used to simulate freeway traffic streams and collect vehicle-maneuvering data. Additionally, an external application program interface, VISSIM's COM-interface, was used to implement the proposed climbing lane operations strategies. Surrogate safety measures (SSM), including the frequency of rear-end conflicts and, were used to quantitatively evaluate the traffic safety using an analysis of individual vehicle trajectories obtained from VISSIM simulations with various operations scenarios. It is expected that the proposed algorithm can be the backbone for operating the climbing lane in real time for safer traffic management.

Sustainable Highway Operations: High Occupancy Lane and Movable Lane

Two managed lane schemes, the high occupancy vehicle lane (HOV) and the movable lane operations, were analyzed to determine their suitability as a sustainable highway operation. VISSIM, a microscopic traffic simulation program, was used for this study, and parameters representing driver behavior in the car following model were calibrated according to a macroscopic speed and flow relationship based on measured data. The analysis results showed that bus travel speed was improved in the HOV operation, while movable lane operation also considerably improved car travel speed.

Self-Adaptive Tolling Strategy for Enhanced High-Occupancy Toll Lane Operations

In this paper, a self-adaptive tolling strategy (SATS) is developed for dynamically and systematically enhancing highoccupancy toll (HOT) lane system operations. This strategy enhances the overall system performance of both the HOT and general purpose (GP) lanes by better utilizing the HOT lane capacity while maintaining high speed and/or high travel-time reliability for HOT lane traffic when GP lanes are congested. To formulate SATS, the Lighthill-Whitham-Richards kinematic wave model is used to characterize HOT lane traffic flow evolution, and the unilateral Laplace transform is used to convert the system representation from the time domain to the frequency domain. Then, an adaptive tolling controller is designed with both the proportional and integral control components. Real-time traffic measurements, including lane occupancy, average speed, and flow rate, are utilized for toll rate calculations. Following a dual-phase control scheme, the appropriate flow rate for HOT lane utilization is computed, and the corresponding toll is estimated backward. To examine the effectiveness of the proposed tolling strategy, microscopic traffic simulation experiments are conducted using VISSIM. The experiment results demonstrate that the proposed tolling strategy performs reasonably well in improving the overall operations of HOT lane systems under various traffic conditions.

Effects of Geometric and Traffic Variables on Double Left-Turn Lane Operations

The goal of this research was to determine the effects of geometric characteristics on double left-turn lane (DLTL) operations, as measured with saturation flow rate (SFR) in units of passenger cars per hour of green per lane (pcphgpl). Data from 26 sites located in three states (Arizona, California, and Texas) were used in the analyses. The average DLTL SFR was 1,775 pcphgpl. The inside–outside lane variable was found to be not significant, which means that the SFRs of the inside and outside lanes are similar. For each additional U-turning vehicle in the left-turn queue, SFR would decrease by 56 pcphgpl after accounting for the effects of other variables in the model. The model results indicate that the addition of a new lane on the receiving leg from a channelized right turn resulted in an SFR increase of about 50 pcphgpl. Width of the left-turn lanes did not significantly affect the SFR. The SFR determination method requires elimination of a queue if a heavy vehicle is present. Therefore, even though the operations of queues with only passenger cars are similar for the various left-turn lane widths studied (9.5 to 13 ft), results for the operations of queues that include heavy vehicles (i.e., trucks or buses) may be different. The width of the receiving leg represents the visual target for left-turning drivers. When the receiving leg width was between 24 and 36 ft, the average SFR was 1,725 pcphgpl, whereas a receiving leg width of 40 to 54 ft was associated with an average SFR of 1,833 pcphgpl. One potential change to practice on the basis of this research is to modify guidance documents to reflect the finding that the capacity of DLTLs is approximately 196% of a single median lane rather than 180%.

Comparative Analysis of Bus Lane Operations in Urban Roads Using Microscopic Traffic Simulation

The research focuses on comparative analysis of three popular types of bus lane operation including roadside exclusive bus lane, bus priority lane and ordinary lane. The analysis is firstly conducted based on simulation tests in PARAMICS with assumed data about traffic situations as well as input parameters. In order to evaluate the results more practically, the research introduces a case study. This case study is conducted at an urban street where there are large numbers of buses and high traffic volumes in Nagaoka City. The results show that with the current traffic situation, the bus priority lane type can help reduce the passenger travel time by 1.2 sec on the 500-meter long segment when compared with the current ordinary lane type. In terms of travel time saving, the paper finally figures out suitable areas for bus lane type applications under various conditions of the main road traffic volume and the number of passengers on the bus.

Simulating High-Occupancy Toll Lane Operations

Microscopic simulation is critical for evaluating the operation strategies of managed lanes. However, most existing tools are limited in their ability to simulate dynamic tolling strategies of managed lanes, particularly those with multiple segments. Three sets of modeling components are developed in this paper to demonstrate simulation of high-occupancy toll (HOT) lane operations. The first component implements three pricing strategies: responsive pricing; a closed-loop, control-based algorithm; and time-of-day pricing. The second component mimics drivers’ lane choice behaviors in the presence of tolls, and the third represents different toll structures for multisegment HOT lane facilities. An enhanced version of CORSIM, which contains these new modeling components, is validated by simulation experiments involving the 95 Express network in South Florida.

Measuring the Quality of Service for High Occupancy Toll Lanes Operations

High Occupancy Toll (HOT) lane systems have been proposed as one of the most applicable countermeasures against freeway congestion. Under HOT lane operational scheme, a Single Occupancy Vehicle (SOV) can pay to access HOT lanes in exchange of travel time saving or enhanced trip reliability when excess HOT lane capacity is available. Compared with regular freeway facilities, HOT lane systems demonstrate unique characteristics in facility capacity, driver behavior, travel pattern, demand modeling, and trip reliability. This study aims at conducting a comprehensive performance analysis on two representative HOT lane systems of State Route 167 in Washington and I-394 MnPass in Minnesota based on the field data collected from traffic sensors and transponder toll tags. Performance measurements are proposed to quantify the quality of service for HOT lane operations. Three critical issues are addressed in this study: 1) the speed-flow relationships in HOT lane systems, 2) quantified system-wide travel time savings and travel time reliability achieved, 3) SOVs tolling incentives. Based on the empirical analysis and evaluation results for the SR 167 and I-394 MnPass HOT lane systems, operational problems and challenges are also identified. Although the HOT lane system preserves favorable travel reliability, under-utilized HOT lane capacities were observed. The existing tolling strategies may be modified for better SOV allocation for HOT lane usages and further optimize the overall HOT system operations. The research findings greatly advance our understanding on HOT lane system operation mechanisms and are complementary to the freeway facility performance analysis provided by Highway Capacity Manual 2000.

Quantifying the Attractiveness of High-Occupancy Toll Lanes with Traffic Sensor Data under Various Traffic Conditions

Different states have used different tolling strategies for their high-occupancy-toll (HOT) lane facilities, and the performance of an HOT lane system has tied directly to the tolling strategy. However, comparing tolling strategies has been a difficult problem because of the lack of field data as well as missing pieces of information critical to the analysis of HOT lane operations. For example, how single-occupancy vehicles (SOVs) choose the type of lane to use under the effect of tolling and the flow friction between HOT and general purpose lanes remains unclear. This research attempts to analyze the heterogeneity among the SOV users of HOT lanes and to quantify the attractiveness of HOT lanes for SOV drivers. The study uses field data collected by point traffic sensors and transponder toll tags on Washington State Route 167 (SR-167). SOVs are categorized as infrequent users and frequent users, according to the frequency with which their transponder identification tags appear in the database. Their value of time distributions are studied separately at the microscopic level. A logit-like model is further developed to quantify the relationship between SOV demand and HOT lane use under different traffic phases. The analysis results show that travel patterns on HOT and general purpose lanes can be better interpreted and modeled for performance enhancement with motorists' willingness to pay HOT lane tolls considered.

Comparative Analysis of Bus Lane Operations in Urban Roads using Microscopic Traffic Simulation

Comparative Analysis of Bus Lane Operations in Urban Roads using Microscopic Traffic Simulation

Optimal dynamic pricing strategies for high-occupancy/toll lanes

This paper proposes a self-learning approach to determine optimal pricing strategies for high-occupancy/toll lane operations. The approach learns recursively motorists’ willingness to pay by mining the loop detector data, and then specifies toll rates to maximize the freeway’s throughput while ensuring a superior travel service to the users of the toll lanes. In determination of the tolls, a multi-lane hybrid traffic flow model is used to explicitly consider the impacts of the lane-changing behaviors before the entry points of the toll lanes on throughput and travel time. Simulation experiments are conducted to demonstrate and validate the proposed approach, and provide insights on when to convert high-occupancy lanes to toll lanes.

Simulation-Based Investigation on High-Occupancy Toll Lane Operations for Washington State Route 167

High-occupancy toll (HOT) lane operation has been implemented in several urban areas in the United States and is regarded as one of the most effective management strategies against freeway congestion. By allowing single occupancy vehicles (SOVs) to pay a toll for using high-occupancy vehicle (HOV) lanes, the excess capacities of HOV lanes can be used and the overall traffic mobility of the roadway section can be improved. However, research on HOT lane operations is still in its early stage. A series of theoretical and practical issues on optimizing HOT lane system performance particularly require immediate attention for better practice. Simulation-based investigation on HOT lane operations provides a cost-effective, risk-free, and prospective means of exploring and addressing these issues. A microscopic traffic simulation tool, VISSIM, is exploited in this study. By overcoming functional constraints with the VISSIM built-in modules and taking advantage of its component object model interface, we develop a new external module to enable HOT lane simulation. This HOT lane module provides additional flexibility to satisfy any specific demands from particular researchers and practitioners. Based on this external module, HOT lane operations can be simulated and evaluated as demonstrated using the Washington State Route (SR) 167 HOT Lane Pilot Project. The SR-167 simulation results not only quantitatively evaluate the overall system performance but also identify potential problems. Significantly different operational performance was illustrated between HOV lane and HOT lane systems using the developed simulation models. The simulation platform used in this study has the potential to be a cost-effective evaluation tool for HOT lane operations.

A Feedback-Based Dynamic Tolling Algorithm for High-Occupancy Toll Lane Operations

Dramatically increasing travel demands and insufficient traffic facilities have induced severe traffic congestion. High-occupancy toll (HOT) lane operation has been proposed as one of the most applicable and acceptable countermeasures against freeway congestion. With balanced pricing and vehicle occupancy constraints, HOT lane operations can realize the optimal traffic allocation and enhance overall infrastructure efficiency. However, few previous studies have concentrated on optimal tolling strategies. Two major problems with inferior tolling strategies degrade HOT lane system performance. First, an undersensitive tolling algorithm is incapable of handling the hysteretic properties of traffic systems and may cause severe response delays. Second, oversensitive characteristics of imperfect tolling strategies may cause unfavorable flow fluctuations in HOT and general-purpose lanes that disrupt traffic operations. A new feedback-based tolling algorithm to optimize HOT lane operations addresses these problems. To decompose the calculation complexity, a second-order control scheme is used in this algorithm. On the basis of traffic speed conditions and toll changing patterns, the optimal flow ratio for HOT lane use is calculated by using feedback control theory. The appropriate toll rate is then estimated backward by using the discrete route choice model. This algorithm is simple, effective, and easy to implement. VISSIM-based simulation tests were conducted to examine its practicality and effectiveness. Test results show that the proposed tolling algorithm performed reasonably well in optimizing overall traffic operations of the HOT lane system under various traffic conditions.

Measuring Impacts of High-Occupancy-Vehicle Lane Operations on Light-Duty-Vehicle Emissions

High-occupancy-vehicle (HOV) lanes on urban highways have long been proved to increase the efficiency of highway operations, as measured by person throughput, vehicle occupancy, travel time, speed, and reliability. Operational measures of effectiveness, such as speed and travel time, for HOV facilities are superior to general purpose (GP) lanes, in which predominantly single-occupancy vehicles operate. Few studies have attempted to study the emissions on HOV facilities vis-à-vis their GP lane counterparts. In this research, differences in vehicle emissions between HOV lane and GP lane facilities were measured with portable emissions sensors. Several hundred miles of on-road emissions data were collected by vehicles instrumented with portable emissions-monitoring systems (PEMSs) operated in HOV and GP lanes during peak hours in the metropolitan Washington, D.C., area. Data were collected at HOV facilities with buffer separation and at HOV facilities with barrier separation (limited-access lanes). Experimental runs were conducted with pairs of nearly identical instrumented vehicles that simultaneously began trips in parallel HOV and GP lanes and ended them at a common location. The experimental design controlled for vehicle type and driver characteristics. Analysis identified the emissions profiles of vehicles operating in barrier-separated HOV lanes (I-95) and vehicles operating in buffer-separated HOV lanes (I-66). Experiences related to the experimental design with the PEMS, the field deployment of the PEMS, data collection, and analysis are discussed. Included in the discussion is a description of the application of a geographic information system for data reduction and analysis.

Measuring Impacts of High-Occupancy-Vehicle Lane Operations on Light-Duty-Vehicle Emissions: Experimental Study with Instrumented Vehicles

High-occupancy-vehicle (HOV) lanes on urban highways have long been proved to increase the efficiency of highway operations, as measured by person throughput, vehicle occupancy, travel time, speed, and reliability. Operational measures of effectiveness, such as speed and travel time, for HOV facilities are superior to general purpose (GP) lanes, in which predominantly single-occupancy vehicles operate. Few studies have attempted to study the emissions on HOV facilities vis-a-vis their GP lane counterparts. In this research, differences in vehicle emissions between HOV lane and GP lane facilities were measured with portable emissions sensors. Several hundred miles of on-road emissions data were collected by vehicles instrumented with portable emissions-monitoring systems (PEMSs) operated in HOV and GP lanes during peak hours in the metropolitan Washington, D.C., area. Data were collected at HOV facilities with buffer separation and at HOV facilities with barrier separation (limited-access lanes). Experimen...

So You Want to Make a High-Occupancy Toll Lane?: Project Manager's Guide for Conversion from High-Occupancy Vehicle Lane to High-Occupancy Toll Lane

Although high-occupancy toll (HOT) lanes have been studied or have existed for more than 10 years, the continuing developmental nature of these concepts means that there is little guidance for project managers on how to manage the process of converting a high-occupancy vehicle (HOV) lane to a HOT lane. Many guidelines have been published about the technical elements of HOT lane development and operations. A project manager of an HOV to HOT lane conversion process would face issues that differ from those of the typical highway construction project, and managing these issues can be difficult and arduous. The intent of this paper is to address issues from the perspective of the implementing agency's project manager. Eight specific issues to be addressed within the conceptual development of the HOT lane conversion process are identified here: (a) presence of significant and predictable excess capacity in the HOV lanes, (b) presence of significant and recurring congestion in the adjacent general purpose lanes,...

So you want to Make a High-Occupancy Toll Lane?

Although high-occupancy toll (HOT) lanes have been studied or have existed for more than 10 years, the continuing developmental nature of these concepts means that there is little guidance for project managers on how to manage the process of converting a high-occupancy vehicle (HOV) lane to a HOT lane. Many guidelines have been published about the technical elements of HOT lane development and operations. A project manager of an HOV to HOT lane conversion process would face issues that differ from those of the typical highway construction project, and managing these issues can be difficult and arduous. The intent of this paper is to address issues from the perspective of the implementing agency's project manager. Eight specific issues to be addressed within the conceptual development of the HOT lane conversion process are identified here: (a) presence of significant and predictable excess capacity in the HOV lanes, (b) presence of significant and recurring congestion in the adjacent general purpose lanes, (c) nature of traffic separation on the HOV lanes, (d) primary means of funding for the HOV lanes, (e) identification of the HOT lane program's primary objective, (f) determination of the appropriate implementing agency, (g) avoidance of overwhelming public opposition, and (h) ability to build political support for the process. This paper has summarized the first of what the authors see as four steps to the successful conversion of an HOV lane to a HOT lane: conceptual development. Planned subsequent papers will address the remaining three steps: program design, implementation, and ongoing operations.

Operational Effect of Single-Occupant Hybrid Vehicles in High-Occupancy Vehicle Lanes

In an effort to reduce the environmental impact of automobile travel, legislatures across the country are considering laws that would allow single-occupant hybrid vehicles to use high-occupancy vehicle (HOV) lanes. In time, single-occupant hybrid vehicles could increase congestion in HOV lanes such that the travel time incentive would be lost. A microscopic simulation method is presented; it examines the possible effects of a proposed California state hybrid HOV law that would allow singleoccupant hybrid vehicles into the state's HOV network. The results from a 12-by-16-mi freeway network being simulated around Irvine, California, under several travel demand scenarios show that the policy would not have a significant effect on HOV lane operations in the study area. Although the addition of single-occupant hybrids may have only a modest impact on short-run HOV lane operations, policy implementation opens the door to more difficult long-term policy questions.