Traffic merging in urban environments is one of the main causes of traffic congestion. From the driver's point of view, the difficulty arises along the on-ramp where the merging vehicle's driver has to discern whether he should accelerate or decelerate to enter the main road. In parallel, the drivers of the vehicles already on the major road may have to modify their speeds to permit the entrance of the merging vehicle, thus affecting the traffic flow. This paper presents an approach to merging from a minor to a major road in congested traffic situations. An automated merging system that was developed with two principal goals, i.e., to permit the merging vehicle to sufficiently fluidly enter the major road to avoid congestion on the minor road and to modify the speed of the vehicles already on the main road to minimize the effect on that already congested main road, is described. A fuzzy controller is developed to act on the vehicles' longitudinal control - throttle and brake pedals - following the references set by a decision algorithm. Data from other vehicles are acquired using wireless vehicle-to-infrastructure (V2I) communication. A system installed in the infrastructure that is capable of assessing road traffic conditions in real time is responsible for transmitting the data of the vehicles in the surrounding area. Three production vehicles were used in the experimental phase to validate the proposed system at the facilities of the Centro de Automatica y Robotica with encouraging results.

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Automated On-Ramp Merging System for Congested Traffic Situations

The longitudinal vehicle control problem associated with any automated transportation scheme is discussed. The two fundamental aspects of the problem are the logical aspect and the control aspect. The logical aspect of the problem concerns the decision of where vehicles should be at a future time, based on present system conditions, so that the level of service delivered by the system is good. The control aspect is concerned with how to control vehicles to attain and maintain their desired positions while giving a comfortable ride, not taking too long, not exceeding car capabilities, and maintaining safety. Previous work dealing with both the logical and control aspects of the longitudinal vehicle control problem is briefly reviewed. One approach to handling the logical aspects of the merging problem in automated systems assumes that vehicles occupy positions on a guideway within hypothetical “cells” that move at a constant velocity. This approach simplifies the logical aspect of the longitudinal control ...

A Moving Cell Control Scheme for Automated Transportation Systems

The synchronous longitudinal guidance (SLG) approach to allocating guideway space and controlling traffic in a ground transportation network is described in this paper. The transportation system considered is one in which completely automated vehicles follow deterministic position-time profiles during their travel through the network. The key feature in the SLG approach is a dynamic scheduling algorithm which allocates guideway space to vehicles in such a way that the capacity of critical points (or bottlenecks) in the network is not exceeded. This guarantees that traffic flows smoothly through the entire network and that queues are confined to the entrances. Two scheduling algorithms are Identified in this paper. The basic slot allocation algorithm used in processing vehicle trip requests is outlined first. Then the more general cycle allocation algorithm, which is suitable for control of large networks, is described. The results of a computer simulation of a network run using the latter algorithm are summarized, and the required auxiliary SLG functions of entrance and exit control, merge control, and safety assurance are discussed briefly.

How to Run an Automated Transportation System

The control problems associated with the operation of a network of automatically controlled closely spaced high-speed vehicles are considered. A system operating concept based on the synchronous moving-cell approach to individual vehicle control is presented. The need for a network traffic-management strategy is pointed out and one such strategy, called cycle preprogramming, is discussed. Finally, a study of the efficiency of the cycle preprogramming traffic-management strategy is described.

Control aspects of a dual-mode transportation system

This paper describes the modeling and simulation of a single merge function, having two input lanes and one output lane, operating in a quasi- synchronous network. The simulation described here differs from previous merging models by permitting slots to be of variable length to accommodate trains of different lengths, and allowing unlimited maneuvering of trains. It has the unique ability to represent the operation of a special newly devised concatenating merge, which permits trains arriving on separate input lanes to combine themselves into a longer train at the merge. The results reported in this paper demonstrate the ability of vehicle entrainment and platooning to significantly increase guideway system capacity.

Operation of merge junctions in a dynamically entrained automated guideway transit system

Thesis (Sc. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1968.

Michael Bick Godfrey

Papers

Merging in automated transportation systems.