A novel application of pre-signals to improve the performance of signalized intersections: Evaluation through simulation

To ponder less costlier solutions to solve traffic congestion problems at signalized intersections, this paper proposes a novel application consisting of using pre-signals. Hence, an agent-based traffic simulation model was developed, where it is possible to model different types of intersections - including roundabouts of different sizes - and quantify and compare their performance. By analyzing the simulation results, it was found that: on the intersection with pre-signals, an increase in the flow of 10% and 3% was registered, the vehicles spent 1 and 2 less minutes to cross the intersection and the fuel consumption was decreased in 22% and 44%, in comparison to regular intersections and roundabouts, respectively. Concerning the size of queues, it was noted that the queues of the regular intersection were 60 meters longer than the queues on the intersection with pre-signals and on the roundabout. Based on these findings, and by making cost assumptions, a small cost analysis was made, which indicates that at least 1 million € could be yearly saved.This work has been supported by FCT –Fundação para a Ciência e Tecnologia within the Project Scope: UID/CEC/00319/2019

A Review of Traffic Signal Control.

The aim of this paper is to provide a starting point for the future research within the SERC sponsored project "Gating and Traffic Control: The Application of State Space Control Theory". It will provide an introduction to State Space Control Theory, State Space applications in transportation in general, an in-depth review of congestion control (specifically traffic signal control in congested situations), a review of theoretical works, a review of existing systems and will conclude with recommendations for the research to be undertaken within this project

Evaluation of when road space prioritisation/infrastructural improvements for paratransit vehicles is warranted: A case study of Mitchells Plain, Cape Town

In many developing countries, the cities have confined or absolute non-availability of modern quality public transport systems, therefore residents of these cities solely rely on non-scheduled, informal, flexible route transportation system referred to as ‘Paratransit’ to move from one point to another. South Africa being a partly developed and partly developing country also have this particular problem in terms of its public transport system. Some 65% of public transport users make use of paratransit services as a day to day means of transport in South Africa. Paratransit is the most commonly used public transport mode in South African cities as it is relatively affordable and highly flexible. However, it is referred to be very unreliable in terms of journey time and passenger’s waiting time at stops mostly, due to time wasted in traffic congestion and at signalised intersections. So, actions are needed to be taken to improve the travel speed, safety and reliability of paratransit vehicles. In 2007, South Africa’s department of transport envisioned some strategies to revitalise public transport system in South Africa whereby one of the strategies is to replace paratransit called Mini-bus taxi in South Africa with scheduled trunk-feeder services. However, this has proven unachievable, due to resistant from the paratransit association. This dissertation aims to investigate under which traffic condition is road prioritisation/infrastructural improvement is warranted for paratransit vehicles in a trunk-feeder hybrid setting. The dissertation also explored how operations of the paratransit feeders service can be improved through infrastructural improvements and prioritisation on road space using the Mitchells Plain public transport interchange as a case study. An agent-based simulation modelling tool is employed to simulate the present trunk-feeder operations at the Mitchells Plain interchange thereby investigating how the passenger travel performance has been impacted by the configuration and operational characteristics of the current trunk-feeder public transport system. The modelling tool mimic an intermodal trunk feeder operation which include: Passengers arrival at the rank and stops to wait for taxi; boarding and alighting of passengers along the feeder’s route; transfers of passengers alighting from the taxi and walking of the passengers through the interchange to connect to their respective available trunk service public transport system. The main aim of this dissertation is to develop and investigate various infrastructure developments to the road network using road space prioritisation that can be implemented and their effect on the overall efficiency of the paratransit feeder’s system. Each of the proposed infrastructural improvements through prioritisation of paratransit vehicles on road space was tested in a normal and congested traffic condition to evaluate their effectiveness on the operational efficiency of paratransit feeder’s service at varying level of traffic congestion. The effect of the various network infrastructure improvements is being tested using the agent-based simulation tool with the main objectives of improving the operational performance of the paratransit feeder’s services which will lead to a more coordinated, integrated and sustainable trunk-feeder public transport system. The result of the model analysis showed that provision of dedicated lanes for paratransit vehicles is the most efficient infrastructural improvement strategy through road space prioritisation, especially in a traffic-congested route

MODELLING THE SURROGATE SAFETY OF VARIOUS LEFT-TURN PHASE SEQUENCES

Left-turns are the most complex maneuvers in a signalized intersection. Based on the flow of the traffic volume through a given intersection, the left-turn phasing may be controlled in various fashions such as: protected only, permissive only, and protected/permissive. Following the introduction of the flashing yellow arrow (FYA) to the 2009 Edition of the Manual on Uniform Traffic Control Devices (MUTCD), many state agencies have implemented these indications for their left-turn permissive movements. Similar to the existing circular green (CG) permissive indication, the FYA requires drivers to yield to oncoming vehicles before making their left-turn. However, given the novelty of these traffic control devices there is a lack of standardization when it comes to the transition between protected and permissive left-turn phasing. A need exists to evaluate the surrogate safety of their implementation through a means of microsimulation evaluation. This research endeavor aims to model various protected-permissive left-turn (PPLT) phase sequences in the FHWA Surrogate Safety Assessment Model (SSAM). Both the FYA and circular green permissive left-turn indications will be implemented in VISSIM microsimulation models. Further, the phase sequencing for each permissive indication will comprise of two sequence options upon transitioning between protected and permissive left-turns; transitioning with and without the all-red clearance interval. Ultimately, this investigation will yield results to develop guidance for practitioners in designing the signal sequencing with PPLT phasing, particularly with the newly introduced FYA traffic control device

Evaluation of Traffic Simulation Models for Work Zones in the New England Area

There are many traffic simulation modeling packages in existence, some of which are designed specifically for work zone analysis. These packages include, for example QUEWZ, Quick Zone, CORSIM and VISSIM. This research evaluates the capabilities of these simulation packages to determine whether or not these packages produce reasonable impact estimates. The research concludes with a set of recommendations to assist transportation professionals in selecting the most appropriate simulation package for a particular work zone project

DEVELOPMENT OF A MIXED-FLOW OPTIMIZATION SYSTEM FOR EMERGENCY EVACUATION IN URBAN NETWORKS

In most metropolitan areas, an emergency evacuation may demand a potentially large number of evacuees to use transit systems or to walk over some distance to access their passenger cars. In the process of approaching designated pick-up points for evacuation, the massive number of pedestrians often incurs tremendous burden to vehicles in the roadway network. Hence, one critical issue in a multi-modal evacuation planning is the effective coordination of the vehicle and pedestrian flows by considering their complex interactions. The purpose of this research is to develop an integrated system that is capable of generating the optimal evacuation plan and reflecting the real-world network traffic conditions caused by the conflicts of these two types of flows. The first part of this research is an integer programming model designed to optimize the control plans for massive mixed pedestrian-vehicle flows within the evacuation zone. The proposed model, integrating the pedestrian and vehicle networks, can effectively account for their potential conflicts during the evacuation. The model can generate the optimal routing strategies to guide evacuees moving toward either their pick-up locations or parking areas and can also produce a responsive plan to accommodate the massive pedestrian movements. The second part of this research is a mixed-flow simulation tool that can capture the conflicts between pedestrians, between vehicles, and between pedestrians and vehicles in an evacuation network. The core logic of this simulation model is the Mixed-Cellular Automata (MCA) concept, which, with some embedded components, offers a realistic mechanism to reflect the competing and conflicting interactions between vehicle and pedestrian flows. This study is expected to yield the following contributions * Design of an effective framework for planning a multi-modal evacuation within metropolitan areas; * Development of an integrated mixed-flow optimization model that can overcome various modeling and computing difficulties in capturing the mixed-flow dynamics in urban network evacuation; * Construction and calibration of a new mixed-flow simulation model, based on the Cellular Automaton concept, to reflect various conflicting patterns between vehicle and pedestrian flows in an evacuation network

Agent-based micro simulation to assess the performance of roundabouts considering different variables and performance indicators

Traffic congestion problems in intersections are usually solved by building infrastructures such as roundabouts. Several variables influence its performance, e.g. geometry, size and driving behaviour. Thus, it becomes necessary to compare these variables. This paper proposes a simulation model, developed to compare the performance of roundabouts, employing the object and agent modelling paradigms of Simio, to model the individual behaviour of vehicles. The results indicate the optimum size of roundabouts is around 40 meters of diameter and that the driving style has a greater influence on the performance of the roundabout than its unbalancing. In addition, it was found that roundabouts considering unbalancing and human behaviour decreased: The flow of vehicles in 8%, the waiting time per vehicle in 3 minutes, the queue size in 90%, the number of stops per vehicle in 88% and vehicles spent three times more fuel, than the roundabouts that did not consider these variables.(undefined)info:eu-repo/semantics/publishedVersio

Utilizing Simulated Vehicle Trajectory Data from Connected Vehicles to Characterize Performance Measures on an Arterial After an Impactful Incident

Traffic incidents are unforeseen events known to affect traffic flow because they reduce the capacity of an arterial corridor segment and normally generate a temporary bottleneck. Identification of retiming requirements to enhance traffic signal operations when an incident occurs depends on operations-oriented traffic signal performance measurements. When effective and real-time traffic signal performance metrics are employed at traffic control centers, delays, fuel use, and air pollution may all be decreased. The majority of currently available traffic signal performance evaluations are based on high-resolution traffic signal controller event data, which gives data on an intersection-by-intersection basis but requires a substantial upfront expenditure. The necessary detecting and communication equipment also involves costly and periodic maintenance. Additionally, the full manifestation of connected vehicles (CVs) is fast approaching with efforts in place to accelerate the adaptation of CVs and their infrastructures. CV technologies have enormous potential to improve traffic mobility and safety. CVs can provide abundant traffic data that is not otherwise captured by roadway detectors or other methods of traffic data collection. Since the observation is independent of any space restrictions and not impacted by queue discharge and buildup, CV data offers more comprehensive and reliable data that can be used to estimate various traffic signal performance measures. This thesis proposes a conceptual CV simulation framework intended to ascertain the effectiveness of CV trajectory-based measures in characterizing an arterial corridor incident, such as a vehicle crash. Using a four-intersection corridor with different signal timing plans, a microscopic simulation model was created in Simulation of Urban Mobility (SUMO), Vehicles in Network Simulation (Veins) and Objective Modular Network Testbed in C++ (OMNeT++) platforms. Furthermore, an algorithm for CVs that defines, detects and disseminates a vehicle crash incident to other vehicles and a roadside unit (RSU) was developed. In the thesis, it is demonstrated how visual performance metrics with CV data may be used to identify an incident. This thesis proposes that traffic signal performance metrics, such as progression quality, split failure, platoon ratios, and safety surrogate measures (SSMs), may be generated using CV trajectory data. The results show that the recommended approaches with access to CV trajectory data would help both performance assessment and operation of traffic control systems. Unlike the current state of the practice (fixed detection technology), the developed conceptual framework can detect incidents that are not captured by intersection-vicinity-limited detectors while requiring immediate attention