Papers by Yorgos Stephanedes
Transportation research procedia, 2019
Real time public trasnport information systems in SCOPE
The objective of this work is to demonstrate the use of Advanced Transport Telematics (ATT) in a ... more The objective of this work is to demonstrate the use of Advanced Transport Telematics (ATT) in a multimodal transport environment. The focus of the work is on the integration of ATT methods to increase the share of public transport in the modal-split pattern, improve the efficiency of the available road and transport infrastructure, and enhance the efficiency of multimodal transport networks. The paper describes the characteristics of an integrated traveler information system for two port cities within SCOPE, a DRIVE II project. The system under consideration collects, evaluates, coordinates and disseminates real-time and forecast information on the transport network and service conditions for travelers arriving and departing from the port, by road, bus, rail, ferries and air.
Disaggregate Demand Models for Grain Transport
Disaggregate, linear - probability demand models are presented for estimating the truck and rail ... more Disaggregate, linear - probability demand models are presented for estimating the truck and rail shares in grain movements. The analysis is based on shipments from country grain elevators in Minnesota, North Dakota and South Dakota and destined to the Twin Cities. Results indicate that shipment size, freight rate and service availability time are the most significant determinants of modal decisions. The models can estimate the impact of shipment characteristics and service policies on modal split.
Towards Intelligent Ridesharing for Seamless Multimodal Transport
19th ITS World CongressERTICO - ITS EuropeEuropean CommissionITS AmericaITS Asia-Pacific, 2012
The work focuses on designing a rational and user driven ridesharing service that seeks to allay ... more The work focuses on designing a rational and user driven ridesharing service that seeks to allay safety concerns and support sustainability through user involvement. Not unlike flexible and instant carpooling, commuters are linked for sharing a trip or part of it. However, the design does not place commuters in a permanent arrangement but focuses on sharing a trip within a short time. It expands the flexibility of carpooling to meet a wide variety of travel requirements, including irregularly-timed commutes, very short commutes and non-commutes. The intelligence of the service encompasses use patterns suitable for fully nomadic environments by exploring global positioning system (GPS) capabilities of mobile terminals. It includes provisions for increased safety through a multilevel matching filter. An intelligent-agents based engine matches offers and requests on the basis of individual profiles. Intelligent profiling automatically assigns scores to stated preferences based on weights. A scheduling engine intelligently matches partial routes with other transport modes to produce trip matching and interact with wide-scale multimodal trip intelligent transportation system (ITS) platforms.
Integrated Traffic Management And Traveler Information In A Multimodal Network
In the United States urban travel increases at a rate of 4% per year, while it is estimated that ... more In the United States urban travel increases at a rate of 4% per year, while it is estimated that construction of new facilities will accommodate less than one-fourth of the additional demand (TRB, 1991). Intelligent Vehicle/Highway System (IVHS) technology takes advantage of modem surveillance, communications, computer, and control technologies both in-vehicle and in the highway for addressing congestion and improving the mobility, safety, and productivity of the highway transport system (Euler, 1990). Advanced Traffic Management Systems (ATMS), and Advanced Traveler Information Systems (ATIS) are two important functions of IVHS.The goal of ATMS is to use the increased availability of real-time traffic information to more efficiently manage and control traffic flow in real-time. ATIS seeks to provide travelers with information on roadway conditions, and alternative routing opportunities. Further, IVHS technology can increase the use of public transportation by providing real time information on the operations, i.e. routes, schedules, etc., of the mass transportation system. The objective of this paper is to develop a framework for integrating traffic controllmanagement and traveler information systems for the effective management of traffic in an urban multimodal transport network. This integration should be based on modeling the dynamic interactions between traffic conditions, control/management actions, and traveler decision making.In particular, the paper focuses on the determination of the information needs and the flow of information between the various modules of the proposed framework. 2. DESCRIPTION OF AN INTEGRATED TRAFFIC MANAGEMENT SYSTEM The major objectives of an integrated traffic management system in a multimodal transport network include, continuous monitoring and assessment of the network traffic conditions, realtime management and control of traffic, and development of feedback mechanisms between the traffic authorities and the traffic system. These objectives suggest a system architecture that integrates the collection, processing, and dissemination of information. The traffic monitoring and assessment function of the system involves the collection of traffic data, i.e., volume, speed, occupancy, and data describing the network geometry. These data are required by the incident detection algorithm and the traffic management and control model. The traffic data are collected by inductive loops and Closed Circuit Television (CCTV) or other detecting devices, and are transmitted in real-time to a central data handling facility. Additional, qualitative data on the condition of the network are transmitted to the traffic management center by the traffic police department. Raw traffic data and the results of the incident detection algorithms are input to the traffic management and control module of the system.
Accident Detection at Intersections for Its
Transportation Congress, Volumes 1 and 2: Civil Engineers—Key to the World's Infrastructure, 1995
This paper presents a logic for the detection of accidents at instrument intersections in Advance... more This paper presents a logic for the detection of accidents at instrument intersections in Advanced Traffic Management Systems (ATMS). The logic is based on analysis of volume and occupancy measurements and has modest memory storage requirements.
Transportation Research Record, 1992
Optimal Ramp-Metering Control for Freeway Corridors
Applications of Advanced Technologies in Transportation Engineering, 1991
The paper discusses an optimal ramp-metering control model wherein a corridor is discretized into... more The paper discusses an optimal ramp-metering control model wherein a corridor is discretized into small road sections, with density as the state variable and ramp metering rates, the control variables. In each section the density dynamics are estimated by a continuum model developed with the conservation equation, and formulated as a state equation. The optimization process adjusts the metering rate of each ramp according to corridor traffic conditions such that the total corridor travel time during a certain period is minimum. The paper also presents a test of the optimal metering for a simple one-entrance-ramp segment of the freeway corridor. Fixed signal timing, upstream demands, diversion rates, turning percentages, and initial densities are known and the optimization period is three minutes.
Journal of transportation engineering, Jul 1, 1988
Transportation engineering is a major component of the civil engineering profession. It involves ... more Transportation engineering is a major component of the civil engineering profession. It involves planning, design, construction, maintenance, and operation of transportation facilities. Advanced technologies in the area of information systems, automation, and telecommunications have the potential of achieving cost savings and productivity improvements as well as enabling new developments in transportation. The purpose of this paper is to review the areas where advanced technologies can significantly affect the way transportation engineering is practiced. Strategies for implementation of the necessary changes in practice are also discussed, along with the expected impact on civil engineering curriculum. The emphasis of the paper is on surface transportation. Knowledge-based expert systems (KBES) evolved from research in artificial intelligence with the overall objective of producing intelligent behavior with computers . Numerous artificial intelligence research areas exist, including theorem proving, automatic programming, vision, learning, natural language processing, and others. KBES differ from these other areas by the restriction to a limited problem solving domain such as diagnosis of malfunctions in particular equipment types. These systems are finding a wide range of suitable application areas. Several reviews of transportation (Ritchie 1986; Yeh 1986) and civil engineering Sriram 1986) applications exist. Applications have included a variety of areas such as design ), diagnosis (Ritchie et al. 1986), vehicle control (Weisbin 1986) and operations control . As computer hardware and software develops and as more experience is accumulated, KBES will become a common alternative to conventional programming. The integration of expert systems and conventional programming approaches is likely to be particularly rewarding in this regard ).
Improved Methods for Incident and Traffic Management
PROCEEDINGS OF THE 7TH WORLD CONGRESS ON INTELLIGENT SYSTEMS, 2000
In project PRIME, methods are developed for improving the incident management process. These incl... more In project PRIME, methods are developed for improving the incident management process. These include improvements in incident prediction, incident detection, incident verification, and integrated incident management. Models will estimate the likelihood of occurrence of incidents in real time. The models can be used to activate traffic management and control strategies, thus reducing the likelihood of congestion and incidents. Improving the integration of verification messages, particularly those from mobile sources, will lead to shorter incident response times. Integrating incident management strategy aspects, previously built for either motorways or urban networks, can increase the effectiveness of strategies, and road safety. Off-line and on-line tests will focus on the capabilities of the new techniques, and on the effective use of new information, such as incident estimation and verification. Evaluation will use data from Munich, Southampton and Thessaloniki, with transferability examined at Athens and Barcelona. For the covering abstract see ITRD E114174.
Applications of advanced technologies in transportation engineering : proceedings of the 4th international conference, Capri, Italy, June 27-30, 1995
Transportation research procedia, 2019
Queueing Applications for Stop Sign Operation
A pair of programs has been developed as a teaching tool to illustrate the application of simple ... more A pair of programs has been developed as a teaching tool to illustrate the application of simple queueing principles to transportation problems as taught in an introductory course in Transportation Engineering. Two applications are covered: (1) The operation of a single fee-collecting exit from a parking ramp and (2) The intersection of a pair of one way streets with stop-sign control on the minor street.
Minnesota Intelligent Transportation Systems' Laboratory
Applications of Advanced Technologies in Transportation Engineering, 1996
The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Aug 31, 2011
Advances in real-time data collection, data storage and computational systems have led to develop... more Advances in real-time data collection, data storage and computational systems have led to development of algorithms for transport administrators and engineers that improve traffic safety and reduce cost of road operations. Despite these advances, problems in effectively integrating real-time data acquisition, processing, modelling and road-use strategies at complex intersections and motorways remain. These are related to increasing system performance in identification, analysis, detection and prediction of traffic state in real time. This research develops dynamic models to estimate the probability of road incidents, such as crashes and conflicts, and incident-prone conditions based on real-time data. The models support integration of anticipatory information and fee-based road use strategies in traveller information and management. Development includes macroscopic/microscopic probabilistic models, neural networks, and vector autoregressions tested via machine vision at EU and US sites. 1
Improved Demand Estimation for Rural Work Trips
Transportation Research Record, 1982
A critical review of the most widely accepted rural demand estimation models is performed. Based ... more A critical review of the most widely accepted rural demand estimation models is performed. Based on data collected in two rural towns, a disaggregate specification for rural work-trip modal choice is proposed. The new model includes a set of socioeconomic and a set of policy-relevant variables and can be used for implementing a wide range of transportation policies to improve rural transit system performance. Model variables produce coefficients consistent with the notion, recently found in the literature, that rural commuters are more sensitive to fiscal variables than are urban commuters. Results from comparison tests suggest that demand prediction with the proposed specification is significantly (up to 88 percent) better than with the best of the existing models. (Author)
Single-Station Incident Detection Algorithm (SSID) for Sparsely Instrumented Freeway Sites
Applications of Advanced Technologies in Transportation Engineering, 1996
Heuristic Decision Framework for Upgrading Highway Weight Limits
Transportation Research Record, 1988
A heuristic decision framework is developed for obtaining a regional road development program tha... more A heuristic decision framework is developed for obtaining a regional road development program that optimizes the net benefits of the projects in the program and meets a specified budget constraint. Because a regional network serves a considerable number of plants and markets and consists of a large number of links, the benefits that result from improving a single link are almost never immediately realized. In the case of a program to upgrade highway weight limits, a benefit is realized only when the minimum load limit along a travel route is raised. The heuristic algorithm addresses this special constraint and determines optimal road development plans for various budget levels. Although this analysis concentrates on selecting projects that upgrade the weight limits on state highways, the methodology is also applicable to other types of highway project selection.
Transit System Monitoring and Design Final Report
Forecasting Experiments for Rural Transit Policymakers (Abridgment)
Transportation Research Record, 1979
The paper addresses problems faced by transit managers and funding agencies. Such problems have b... more The paper addresses problems faced by transit managers and funding agencies. Such problems have been identified through the interaction of state and federal officials and during a review of rural transit systems in northern New England performed during the first part of 1978. Some of the first problems that transit managers face are in the initial application for funding and making plans based on socieoeconomic and demogrphic characteristics of the service area. These problems are further complicated by the urgency with which funding agencies expect to see results in order to decide about funding continuation and budget approval, which ultimately results in system delay. The magnitude of this overall system delay depends on four individual delays, each of which is from four months to one year long. These delays have been identified during work on case studies of rural transit systems in northern New England: vehicle acquisition delay, schedule change delay, subsidy award delay, and ridership information delay. A simulation technique is used in the analysis of the effects of different policies on the development of a rural transit system. Results of policy experiments agree with the observed behavior of rural transit systems in northern New England. The technique is useful primarily as a quick turnaround policy-analysis tool. The technique has potential applications for policy analysis at two levels--the managerial level to help in project planning and operation and the fund allocation level to help in decisions about funding approval, funding allocation, and funding renewal.
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Papers by Yorgos Stephanedes