Merging Section Research Articles

A Study on the Relationship Between Capacity Drop and the Number of Lanes in Freeway Merging Sections

A Study on the Relationship Between Capacity Drop and the Number of Lanes in Freeway Merging Sections

Modeling Factors Influencing the Capacity of Motorway Merge Sections Controlled by Ramp Metering

This paper focuses on studying factors which are likely to affect motorway merge capacity when ramp metering controls are in use. A newly developed traffic micro-simulation model has been used for this purpose and the well known ALINEA and Demand-Capacity local ramp metering algorithms were integrated within it. Several parameters such as critical occupancy to trigger the signals, position of ramp traffic signals, position of loop detectors and length of ramp were considered. The effectiveness of ramp metering for a range of traffic flow conditions has been tested for various scenarios to show the range of values where ramp metering is beneficial.

Multi-agent Based Traffic Simulation at Merging Section Using Coordinative Behavior Model

Multi-agent Based Traffic Simulation at Merging Section Using Coordinative Behavior Model

画像データを活用した都市高速合流部における合流ギャップ選択モデル

画像データを活用した都市高速合流部における合流ギャップ選択モデル

Study on an Effectiveness-Evaluation Method of Dynamic Channelization on Merging Sections of Tokyo Metropolitan Expressway

Study on an Effectiveness-Evaluation Method of Dynamic Channelization on Merging Sections of Tokyo Metropolitan Expressway

Improving the efficiency of freight traffic at congested freeway merging sections

This work investigates the effect of heavy commercial vehicles on the traffic characteristics and operation of freeway merging sections and examines potential of intelligent transport system control strategies for freeway merging points to mitigate traffic congestion. Freeways are designed to facilitate the flow of traffic including passenger cars and trucks. The impact of these different vehicle types is not uniform, creating problems in freeway operations and safety particularly in the vicinity of merging sections. There have been very few studies concerned with the traffic behavior and characteristics of heavy vehicles in these situations. This study draws on extensive data captured under a wide range of traffic and geometric conditions using detectors, videotaping, and surveys at several interchanges. The macroscopic detector data were used to identify and quantify the impact of heavy commercial vehicles on the capacity of merging sections. The microscopic data were then utilized to establish a model for the merging and lane changing behavior of heavy vehicles. Based on this behavioral model, a micro-simulation program was developed to simulate the actual traffic conditions. This model evaluates the capacity of a merging section for a given geometric design, flow condition, and traffic composition (presence of freight vehicles). The model is used to develop a variety of intelligent transport system control strategies associated with heavy commercial vehicles in order to design safer and less congested freeway merging points. The implementation of the proposed strategies showed significant improvement in the merging capacity and assisting in reducing the travel time experienced by all vehicles including freight traffic.

Achievement of alternative configurations of vehicles on multiple lanes

Heavy traffic congestion occurs daily at merging sections on a highway. For relieving this congestion, possibility of alternative configuration of vehicles on multiple-lane road at a merging area is discussed in this paper. This is the configuration where no vehicles move aside on the other lane. It has merit in making a smooth merging at an intersection or a junction due to the so-called "zipper effect." We show, by developing a cellular automaton model for multiple lanes, that this configuration is achieved by simple local interactions between vehicles neighboring each other. The degree of the alternative configuration in terms of the spatial increase in parallel driving length is studied by using both numerical simulations and mean-field theory. We successfully construct a theoretical method for calculating this degree of the alternative configuration by using cluster approximation. It is shown that the theoretical results coincide with those of the simulations very well.

ANALYSIS OF SPEED-DENSITY TRAFFIC FLOW MODELS ON A MERGE INFLUENCE SECTION IN UNINTERRUPTED FACILITY

An uninterrupted facility reflects the interrelation of cause and effect on the traffic volume speed density; therefore, if a ramp of traffic flow is merged into the main line at a merged section, single variables (such as speed or density) change, as well as interaction effects. Thus, this study used temporally- and spatially-continuous traffic data for various traffic conditions in order to find changes to correlations and interaction effects in a speed-density traffic flow model with a merging section. These changes were also analyzed in comparison with other sections. As a result of this analysis, it was found that the downstream section where traffic flows (decelerated by merging) can be depicted with Greenshields model and that the spatial transition occurs as traffic flow moves farther downstream. It was also found that the upstream, merge and downstream sections showed heterogeneous traffic flow characteristics, i.e., the free flow speed and the speed change rate versus flow density were different from each other.

自動搬送システムの運行制御とその解析手法

It is important to discuss the behavior of traffic at merging sections for the design and realization of an automated guided vehicle system (AGVS). In this study, we deal with a merging section of the AGVS by considering a time limit for the merging of vehicles. Near the merging section, traffic flowing in one direction must form a queue to avoid collisions between vehicles. We propose an improvement in the control strategy proposed in the previous research. However, it is difficult to analyze the mathematical model of the merging section. Analysis can be performed only for the case in which the time limit is one unit. We also propose a method for analyzing the model for an arbitrary time limit using a linear recurrence relation. We quantitatively discuss the influence of the time limit on the average queue length and the detour rate.

Using ITS to Improve the Capacity of Freeway Merging Sections by Transferring Freight Vehicles

This paper investigates the effect of heavy commercial vehicles on traffic characteristics and operation of freeway merging sections. Freeways are designed to facilitate the flow of traffic, including passenger cars and trucks. The impact of these different vehicle types is not uniform, creating problems in freeway operations and safety, particularly in the vicinity of merging sections. There have been very few studies that are concerned with the traffic behavior and characteristics of heavy vehicles in these situations. Therefore, a three-year study was undertaken to investigate traffic behavior and operating characteristics during the merging process under congested traffic conditions. First extensive traffic data collection captured a wide range of traffic and geometric information using detectors, videotaping, and surveys at several interchanges. The macroscopic detector data were used to identify and quantify the impact of heavy commercial vehicles on the capacity of merging sections. Subsequently, the microscopic data were utilized to establish a model for the behavior of drivers at merging sections. Based on this behavioral model, a microsimulation program was developed to simulate the actual traffic conditions. This model was used to evaluate the capacity of a merging section for a given geometric design and traffic flow condition. In addition, this model was employed to develop a variety of intelligent transport system control strategies that are associated with heavy commercial vehicles with the goal of designing safer and less-congested freeway merging points. The implementation of the proposed control strategies showed significant improvement over the capacity of merging sections.

A Study of a Merging Section of PRT System with Bulk Arrival and its Control Strategy

This paper deals with a merging section of Personal Rapid Transit system with bulk arrival. Vehicles arrive at a merging section from a main line and a sub line. In most of the previous studies on PRT system, vehicles on the main line have priority. Then, a queue is formed only on the sub line. In this situation, the queuing delay on the sub line may become extremely long. We propose a control strategy whereby vehicles on the main line are not stopped in normal situation; vehicles on the main line are only stopped when the number of waiting vehicles on the sub line exceeds some specific number. This specific number is a sort of threshold. Thus, queues are formed on the main line and the sub line, respectively. Both of the queuing delays are controlled with the threshold. The optimal value of the threshold can be obtained by analyzing the stochastic model. By the optimal value, we can set the rate of queuing delay between the main and sub lines to an arbitrary rate.

Study of Driver Gap Acceptance Behavior at Merging Area in Baghdad City

This paper describes a traffic behavior at merging (on-ramp) area in Baghdad city. The objective is to predict the acceptable and critical gap necessary for completing merging process in an on-ramp area for vehicles to enter the highway based on observed traffic data.Data were collected from two selected sites which had certain characteristics both operational and geometrical to fit the criteria needed for gap acceptance study which were presented hereinafter. These two sites were on-ramp sections at Mohamed Al-Qasim highway and the Army-Canal highway.Video-recording equipments were used to collect data. The observed data were analyzed, grouped, and processed using computer programs developed by the researcher for this purpose. Standard statistical analysis techniques were used to examine and analyze the observed data.Gap acceptance results are used to determine the critical gap. Critical gaps are playing main role to evaluate level of service and capacity at Highway merging sections. This study measures gaps in the major stream regarding to driver behavior for traffic stream in the merging area. It has been found that different types of drivers will accept different gaps, more aggressive drivers will accept smaller gaps and conservative drivers accept larger gaps.Keywords / Traffic behavior, Gap acceptance, Critical gap, Merging area, Highway capacity.

Microsimulation of Freeway Ramp Merging Processes Under Congested Traffic Conditions

This paper describes a microsimulation program developed to study freeway ramp merging phenomena under congested traffic conditions. The results of extensive macroscopic and microscopic studies are used to establish a model for the behavior of merging drivers. A theoretical framework for modeling the ramp and freeway lag driver acceleration-deceleration behavior guided the model development. This methodology uses the stimuli-response psychophysical concept as a fundamental rule and is formulated as a modified form of the conventional car-following models. Data collected at the two merging points are used to calibrate the hypothesized ramp and freeway lag vehicle acceleration models. Drawing on this behavioral model, the freeway merging capacity simulation program (FMCSP) is developed to simulate actual traffic conditions. This model evaluates the capacity of a merging section for a given geometric design and flow condition. Validation of FMCSP is performed using the observed flow, vehicle trajectories, and lane-changing maneuvers. The simulation model is applied to investigate a variety of merging strategies. The results indicated that the FMCSP is capable of simulating the actual traffic conditions of congested freeway ramp merging sections and will aid in the development of traffic management strategies for complex freeway ramp merging areas.

Observing freeway ramp merging phenomena in congested traffic

AbstractThis work conducts a comprehensive investigation of traffic behavior and characteristics during freeway ramp merging under congested traffic conditions. On the Tokyo Metropolitan Expressway, traffic congestion frequently occurs at merging bottleneck sections, especially during heavy traffic demand. The Tokyo Metropolitan Expressway public corporation, generally applies different empirical strategies to increase the flow rate and decrease the accident rate at the merging sections. However, these strategies do not rely either on any behavioral characteristics of the merging traffic or on the geometric design of the merging segments. There have been only a few research publications concerned with traffic behavior and characteristics in these situations. Therefore, a three‐year study is undertaken to investigate traffic behavior and characteristics during the merging process under congested situations.Extensive traffic data capturing a wide range of traffic and geometric information were collected using detectors, videotaping, and surveys at eight interchanges in Tokyo Metropolitan Expressway. Maximum discharged flow rate from the head of the queue at merging sections in conjunction with traffic and geometric characteristics were analyzed. In addition, lane changing maneuver with respect to the freeway and ramp traffic behaviors were examined. It is believed that this study provides a thorough understanding of the freeway ramp merging dynamics. In addition, it forms a comprehensive database for the development and implementation of congestion management techniques at merging sections utilizing Intelligent Transportation System.

Characteristics of Breakdown Phenomenon in Merging Sections of Urban Expressways in Japan

This paper aims to investigate the breakdown phenomenon at on-ramp merging sections of urban expressways in Japan. The breakdown events are treated here as a probabilistic phenomenon. Six merging sections at which breakdowns frequently occur are selected to be different in their geometry in relation to acceleration lane length and ramp entrance side. Three different aspects of merging capacity are recognized: the maximum outflow rate before the breakdown, the outflow rate when the breakdown starts to occur, and the outflow rates during the queue discharge period. These outflow aspects are analyzed after they are converted into an equivalent passenger car unit to eliminate the effect of heavy vehicles. Then the probability of breakdown at these sections is investigated as a function of outflow rates. The observed breakdown probabilities follow the Weibull distribution function at all sections, with close values of shape parameter and wide range values of scale parameter. The values of the scale parameter are used to investigate the effects of the acceleration lane length and entrance ramp side. Moreover, the breakdown probability is investigated as a function of the occupancy observed immediately downstream of the merging section. Last, the effects of ramp flow ratio and interval length of aggregated data are discussed.

Modeling the Probability of Freeway Rear-End Crash Occurrence

A microscopic model of freeway rear-end crash risk is developed based on a modified negative binomial regression and estimated using Washington State data. Compared with most existing models, this model has two major advantages: (1) It directly considers a driver's response time distribution; and (2) it applies a new dual-impact structure accounting for the probability of both a vehicle becoming an obstacle (Po) and the following vehicle's reaction failure (Pf). The results show for example that truck percentage-mile-per-lane has a dual impact, it increases Po and decreases Pf, yielding a net decrease in rear-end crash probabilities. Urban area, curvature, off-ramp and merge, shoulder width, and merge section are factors found to increase rear-end crash probabilities. Daily vehicle miles traveled (VMT) per lane has a dual impact; it decreases Po and increases Pf, yielding a net increase, indicating for example that focusing VMT related safety improvement efforts on reducing drivers' failure to avoid crashes, such as crash-avoidance systems, is of key importance. Understanding such dual impacts is important for selecting and evaluating safety improvement plans for freeways.

Image Data Analysis on Traffic Congestion at Merging Section of Urban Expressway

Image Data Analysis on Traffic Congestion at Merging Section of Urban Expressway

Classical dynamics of enhanced low-energy electron-ion recombination in storage rings

Electron-ion recombination observed in storage ring experiments shows a strong enhancement of the recombination rate for highly charged ions with low-energy electrons relative to what standard radiative recombination rates predict. We present detailed simulations of the toroid and solenoid regions of the electron cooler, analyzing the classical dynamics of an electron in the presence of the Coulomb field of the ion, the homogeneous magnetic field inside the cooler, and the transient electric field in the merging section. Both bound and continuum electron dynamics display partially chaotic motion. For bound states we observe stochastic and quasiperiodic $l$ mixing while for continuum electrons we find transient chaos characterized by a fractal generalized reflection function. We determine the modified radiative and field-induced recombination of the electron with a highly charged ion in a storage ring. The obtained absolute excess recombination rates are compared with the experimental data and, overall, reasonable agreement is found. The scaling of the rate with the average relative energy, the ion charge, the magnetic guiding field, and the electron-beam temperatures is analyzed.

Analytical Procedures for Estimating Capacity of Freeway Weaving, Merge, and Diverge Sections

The paper identifies a total of 34 different weaving section configurations that are modeled while operating at capacity using the INTEGRATION software for a wide range of weaving section lengths and travel demand distributions. Subsequently, the simulation results are utilized to develop analytical procedures for estimating the capacity of Type A, B, and C weaving sections. The proposed procedures overcome the shortcomings of the 2000 Highway Capacity Manual (HCM) procedures by considering short (less than 150m) in addition to long weaving section lengths, by accounting for the source and distribution of weaving flow, and by ensuring that the capacity of a weaving section reverts to basic freeway capacity when the volume ratio is zero (no weaving flows) regardless of the weaving section length. The model can also estimate the capacity of merge and diverge sections at the appropriate boundary conditions. The paper demonstrates that the proposed model capacity estimates are consistent with field data while the HCM procedures tend to overestimate weaving section capacities significantly (exceeding 100%).

Synthesis and perspectives of complex crystalline nano‐structures

AbstractResearch on inorganic colloidal nanocrystals has moved from the synthesis of simple structures, such as spherical nanoparticles, to more elaborate particles with shapes such as rods, stars, discs, and branched nanocrystals, and recently to nanoparticles that are composed out of sections of different materials. Nanocrystal heterostructures represent a convenient approach to the development of nanoscale building blocks, as they merge sections with different functionality in the same particle, without the need of inorganic cross‐linkers. The present article gives an overview of synthesis strategies to complex nanocrystals and will highlight their structural properties, as well as discuss some envisaged applications. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)