Merge Conflicts Research Articles

Investigating Benefits of IntelliDrive in Freeway Operations: Lane Changing Advisory Case Study

Abstract IntelliDrive, the integration of vehicles and the infrastructure through wireless communication, has generated great interest in the transportation community. It is widely expected that IntelliDrive will support significantly improved transportation operations. However, there have been few studies investigating (1) how IntelliDrive will be used to improve operations, and (2) how to estimate expected benefits of IntelliDrive operations applications. In this study, the research team investigated the application of IntelliDrive to address merging conflicts created by freeway on-ramps. Although merging conflicts contribute significantly to freeway congestion, transportation engineers have limited options with existing traffic surveillance and management tools. IntelliDrive offers the potential for more active management of the surface transportation system, providing capabilities that may be of significant benefit in ramp management. In this research, a lane changing advisory algorithm was developed ...

Development and Evaluation of Enhanced IntelliDrive-Enabled Lane Changing Advisory Algorithm to Address Freeway Merge Conflict

Freeway merge conflicts contribute significantly to freeway congestion. With the capabilities that will be available in an IntelliDrive environment, which enables vehicle-to-vehicle and vehicle-to-infrastructure communications, new approaches to managing freeway merges are possible. In this paper, an enhanced IntelliDrive enabled lane changing advisory algorithm was developed with a variable gap size concept. This algorithm first calculates anticipated lead–lag gap sizes with the equations of motion prepared for a car and a truck and for three vehicle dynamics (accelerating, maintaining current speed, and decelerating). The algorithm then provides lane changing advisories to freeway main-line vehicles (selected on the basis of the calculated variable gap sizes) to create more space within the ramp merging area. Evaluation conducted with a VISSIM microscopic traffic simulation model of a freeway network in Virginia showed that the proposed algorithm has the potential to address freeway merge conflicts. The maximum operational improvement observed was 6.4% higher average speed in the freeway main line within a merge area. Up to a 5.2% reduction in emissions was achieved. Further analysis conducted in terms of the sensitivity of algorithm performance to driver compliance rates suggested that a very high compliance rate (90% or higher) was necessary for the proposed algorithm to work as intended.

A Conflicts Detection Approach for Merging Formal Specification Views

Specifying software requirements is an important, complicated and error prone task. It involves the collaboration of several people specifying requirements that are gathered through several stakeholders. During this process, developers working in parallel introduce and make modifications to requirements until reaching a specification that satisfies the stakeholders’ requirements. Merge conflicts are inevitable when integrating the modifications made by different developers to a shared specification. Thus, detecting and resolving these conflicts is critical to ensure a consistent resulting specification. A conflicts detection approach for merging Object-Oriented formal specifications is proposed in this paper. Conflicts are classified, formally defined and detected based on the results of a proposed differencing algorithm. The proposed approach has been empirically evaluated, and the experimental results are discussed in this paper.

Synthesis of Unconventional Dynamic Merge Metering Traffic Control for Work Zones

This paper presents an unconventional approach for work-zone bottleneck traffic control through integrating the dynamic late merge with a merge metering via wireless communication at the downstream taper area of a work zone, termed as Dynamic Merge Metering Traffic Control System (DMM-Tracs). The architecture and communication system for the DMM-Tracs, including system components, communication technologies and operation mechanism, are introduced. With this system, the merge metering control will be activated depending on the volume detected at an upstream location of the work-zone bottleneck. If the thresholds of control parameters are met, a merge metering signal installed at the taper area will be activated and approaching vehicles will be informed of the metering situation through flashing signage or changeable message sign installed in the advance areas of the work zone. To reduce enforced merges and potentials of merge conflicts, the control scheme will be adjusted on the real-time basis depending on the detected traffic conditions. This potentially increases the efficiency with which the traffic is discharged into the open lane inside the work zone. A portable controller is the “brain” of the DMM-Tracs to receive data from detectors, process the data, and control the merge metering signal via wireless communications. The efficacy of the DMM-Tracs is evaluated via a microsimulation test bed with the state-of-the-art microscopic simulation software VISSIM. Meanwhile, the volume threshold values are also determined via the simulation. The simulation results indicate that higher lane-closure percentage of the bottleneck, more applicable the DMM-Tracs.

Safety Evaluation of Truck Lane Restriction Strategies Using Microsimulation Modeling

The demand for goods and services in North America has increased dramatically over the past few decades. This demand increase resulted in an associated increase in truck traffic on North American highways, escalating congestion, operation, and safety concerns. This in turn has led to increasing interest in strategies to reduce interaction between trucks and cars, including truck restrictions and dedicated truck lanes. The purpose of this paper is to implement algorithms for evaluating safety measures for different scenarios of truck lane restrictions and dedicated truck lanes using microscopic traffic simulation. The measures of performance calculated in this study are lane changing, merging, and rear-end conflicts. These measures are analyzed for truck-restricted lanes and dedicated truck lanes on the Gardiner Expressway in downtown Toronto, Canada. Simulation scenarios are developed by varying lane strategies and truck percentage. Simulation results showed that implementation of a single truck-restricted lane makes little difference to most conflict measures. Restricting trucks from the leftmost two lanes results in more substantial reductions in lane changing conflicts, but causes some increased freeway merging conflicts involving trucks. Dedicating the leftmost lane only to trucks also reduces lane changing conflicts but increases lane merging conflicts. Because lane changing conflicts are far more frequent than merging conflicts, there appears to be a net safety benefit by either restricting trucks from the left two lanes or dedicating the left lane to trucks. Relationships between lane strategy and rear-end conflicts are weak. Truck lane strategies are most effective when truck percentage exceeds 15%.

Effective Software Merging in the Presence of Object-Oriented Refactorings

Current text based Software Configuration Management (SCM) systems have trouble with refactorings. Refactorings result in global changes which lead to merge conflicts. A refactoring-aware SCM system reduces merge conflicts. This paper describes MolhadoRef, a refactoring-aware SCM system and the merge algorithm at its core. MolhadoRef records change operations (refactorings and edits) used to produce one version, and replays them when merging versions. Since refactorings are change operations with well defined semantics, MolhadoRef treats them intelligently. A case study and a controlled experiment show that MolhadoRef automatically solves more merge conflicts than CVS while resulting in fewer merge errors.

토픽 분할에 의한 토픽맵 매칭 및 통합 기법

본 논문에서는 토픽맵의 모델 특성을 고려한 토픽맵 매칭 및 통합 기법을 제안한다. 이전까지의 대부분의 스키마 매칭 연구들은 계산 시간의 효율성을 고려하지 않고 매칭 기법의 범용성 및 정확성을 높이기 위한 목적으로 개발되어 왔다. 그러나 현재 표준적인 온톨로지 언어로 RDF/OWL과 토픽맵이 사용되고 있으며 앞으로 많은 온톨로지들이 이들 언어로 구현될 것이다. 따라서 본 논문에서는 토픽맵 데이터 모델의 구조적 특성 및 제약조건을 고려하여 토픽 분할, 토픽명기반 매칭연산, 속성기반 매칭연산, 계층구조기반 매칭연산, 연관관계기반 매칭연산 및 통합 알고리즘을 개발함으로써 효과적이면서 효율적인 토픽맵 매칭 및 통합이 가능함을 보인다. In this paper, we propose a topic maps matching and merging approach based on the syntactic or semantic characteristics and constraints of the topic maps. Previous schema matching approaches have been developed to enhance effectiveness and generality of matching techniques. However they are inefficient because the approaches should transform input ontologies into graphs and take into account all the nodes and edges of the graphs, which ended up requiring a great amount of processing time. Now, standard languages for developing ontologies are RDF/OWL and Topic Maps. In this paper, we propose an enhanced version of matching and merging technique based on topic partitioning, several matching operations and merging conflict detection.

Urban Freeway On-Ramps

In this paper the influences of the ramp flow on the freeway flow are deemed invasive influences because the freeway vehicles' priority is violated and the freeway flow is interrupted. Understanding of the invasive influences of the freeway entry process helps to promote efficient and safe operations of the main-line facility and to identify more straightforward indicators of level of service (LOS) for freeway on-ramp segments. First, on the basis of field observations conducted at three on-ramp sites along I-35 within the greater Kansas City, Kansas and Missouri, metropolitan area, ramp merging behavior of vehicles in platoons was identified as the direct cause of invasive influences on the freeway flow. Then, the significance of the invasive influences was evaluated in accordance with the evasive events performed by freeway drivers. These evasive events, instigated by merging conflicts, include slowdown and lane change actions. Finally, more straightforward LOS indicators were recommended for improving the current (2000) Highway Capacity Manual LOS evaluation procedure for freeway on-ramp segments.

Merging workflows: A new perspective on connecting business processes

This paper describes the concept of workflow merge and methods for merging business processes. We grouped merges in four categories according to the type of merge: sequential, parallel, conditional, and iterative, and describe the corresponding algorithms for performing these operations. We give results that allow us to determine whether a merge operation is sound. It is shown that to avoid invalid merges, one should choose merge points between which a sub-workflow, called a merge region, is well structured. These findings can provide useful guidance for future workflow merge research. We also raise issues of more complex merge problems, such as merge conflicts, semantic ambiguities and workflow splits.

Refactoring-aware versioning in Eclipse

To fully support refactorings in a team development environment we have implemented a refactoring-aware repository provider as an extension plug-in to the Java Development Tools in Eclipse. The versioning system treats refactorings as first-class changes described as semantic ac- tions rather than the set of resulting changes scattered over the source tree. We also introduce refactoring-aware merge, which merges refactorings as well as traditional changes utilizing the se- mantics of the refactorings to detect and resolve merge conflicts. It also ensures that the semantic meaning of a refactoring is preserved after the merge.

Truck Delay and Traffic Conflicts Around Weigh Stations: A Case Study in Illinois

Truck weight enforcement helps protect infrastructure and improve traffic safety. However, requiring all trucks to stop at all weigh stations reduces productivity and increases enforcement costs. This pilot study was conducted at the Williamsville weigh station in Springfield, Ill., to quantify the delay and traffic conflicts experienced by trucks around weigh stations. The quantification is needed to evaluate the effectiveness of automatic vehicle identification/weigh in motion (AVI/WIM) systems for electronic screening of trucks at weigh stations. The main emphasis of this project is to examine potential benefits of intelligent transportation system (ITS) technologies for intrastate commercial vehicle operations (CVO) applications. Reducing the number of traffic conflict incidents due to the merging and diverging movements of trucks would increase traffic safety. In the case study, without the AVI/WIM system, on the average, 30 percent of all trucks could not be weighed because the weigh station was temporarily closed to prevent a queue backup. The average delay was 4.95 min/truck and varied from 3.56 to 6.59 min/truck. The maximum delay varied from 8.69 to 137.62 min/truck. There were significant numbers of conflicts even under light-volume conditions. Models to predict the number of conflicts were developed. The number of diverge conflicts depends on car and truck volumes, and the number of merge conflicts depends on the truck volume on the ramp and the car volume in the right and middle lanes of a six-lane interstate.

Safety evaluation of flashing amber operation at signalized intersections

The safety of a flashing amber signal for all directions at off-peak hours as a replacement for regular traffic signal operations was evaluated. The proposed control strategy was motivated by the need for energy conservation through reduced amounts of acceleration and of idling time of vehicles. The methodology of the study employed as a measure a broadened definition of “conflict” that freed observers from the need to detect only emergency evasive manoeuvres and decreased their subjective interpretations. Observations were carried out by trained observers at a sample of intersections, using two control strategies: full signal operation and flashing amber phase. Stationed at each leg of an intersection, the observers noted the travel direction of any two vehicles involved in a conflict. The results showed that the most frequent type of conflict under full signal operation was of the rear-end type; during the flashing amber operation, crossing and merging conflicts were dominant. It was concluded that up to a volume of 600 vehicles per hour, flashing operation does not increase the number of conflicts.

Intersection merge control in automated transportation systems

Merging algorithms capable of resolving conflicts in automated transit systems are studied. The effectiveness of five basic algorithms are compared via theoretical evaluations of the ability of each algorithm to resolve merge conflicts. The measure of efficiency is the miss-turn rate, the probability of successfully completing a desired merge. The miss-turn rate for each algorithm is calculated as a function of guideway density and turn rate. Four of these algorithms are sequential strategies while the fifth is a dependent maneuver philosophy.