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    <title>Transport Research International Documentation (TRID)</title>
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    <copyright>Copyright © 2026. National Academy of Sciences. All rights reserved.</copyright>
    <docs>http://blogs.law.harvard.edu/tech/rss</docs>
    <managingEditor>tris-trb@nas.edu (Bill McLeod)</managingEditor>
    <webMaster>tris-trb@nas.edu (Bill McLeod)</webMaster>
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      <title>Transport Research International Documentation (TRID)</title>
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      <title>Traffic Signal Cycle Control With Centralized Critic and Decentralized Actors Under Varying Intervention Frequencies</title>
      <link>https://trid.trb.org/View/2487937</link>
      <description><![CDATA[Traffic congestion in urban areas is a significant problem, leading to prolonged travel times, reduced efficiency, and increased environmental concerns. Effective traffic signal control (TSC) is a key strategy for reducing congestion. Unlike most TSC systems that rely on high-frequency control, this study introduces an innovative joint phase traffic signal cycle control method that operates effectively with varying control intervals. The authors' method features an adjust all phases action design, enabling simultaneous phase changes within the signal cycle, which fosters both immediate stability and sustained TSC effectiveness, especially at lower frequencies. The approach also integrates decentralized actors to handle the complexity of the action space, with a centralized critic to ensure coordinated phase adjusting. Extensive testing on both synthetic and real-world data across different intersection types and signal setups shows that their method significantly outperforms other popular techniques, particularly at high control intervals. Case studies of policies derived from traffic data further illustrate the robustness and reliability of their proposed method.]]></description>
      <pubDate>Mon, 05 May 2025 09:08:09 GMT</pubDate>
      <guid>https://trid.trb.org/View/2487937</guid>
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    <item>
      <title>Beyond centralization: Non-cooperative perimeter control with extended mean-field reinforcement learning in urban road networks</title>
      <link>https://trid.trb.org/View/2400571</link>
      <description><![CDATA[Perimeter control is a traffic management approach aimed at regulating vehicular accumulation within urban regional networks by managing flows on all border-crossing roads. Methods based on the macroscopic fundamental diagram (MFD) fall short in providing specific metering for individual roads. Recent advancements in the cell transmission model (CTM) have attempted to address this limitation but are hindered by their reliance on centralized control, which requires the availability of full information and authority over traffic generation sites. The authors' study proposes an innovative decentralized, game-theoretical framework for perimeter control to address these practical challenges. It is structured around two key groups of agents: perimeter agents, tasked with managing border roads, and interior agents, focused on traffic within generation sites. The framework also incorporates mechanisms for interactions between these agents and the road network, aiming to optimize their individual utilities. Additionally, the authors have developed a multi-agent reinforcement learning (RL) algorithm, extending the mean-field theory concept, to address the complexity of simultaneous learning by multiple agents.]]></description>
      <pubDate>Fri, 26 Jul 2024 10:44:57 GMT</pubDate>
      <guid>https://trid.trb.org/View/2400571</guid>
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      <title>Parallel Testing for Centralized Traffic Control Systems of Intelligent Railways</title>
      <link>https://trid.trb.org/View/2292392</link>
      <description><![CDATA[The centralized traffic control (CTC) system of intelligent railways plays a vital role in implementing railway dispatching, improving transportation efficiency, and ensuring train safety. However, with the development of high-speed railways (HSRs), the construction of new lines and the upgrading of existing equipment have become increasingly prevalent, posing significant challenges to the safety and reliability of the CTC system. To address these challenges, this article proposes a scenario-driven parallel testing method for the CTC system. The authors use divisible and combinable scenarios to describe the functionality and processes of testing. Building upon the scenario representation, a virtual-real interactive testing method is adopted, where virtual testing is employed to generate a large number of scenarios simultaneously, thereby accelerating the testing process of the CTC system while ensuring comprehensive testing coverage. Field testing is carried out to validate the reliability of the CTC system in real operational environments, particularly in critical scenarios. The CTC parallel testing system has been deployed in multiple railway bureaus in China, and the deployment results demonstrate that parallel testing can improve testing efficiency, alleviate tester workload, augment the proficiency of on-site construction, and boost the stability and reliability of CTC systems.]]></description>
      <pubDate>Tue, 28 Nov 2023 10:37:12 GMT</pubDate>
      <guid>https://trid.trb.org/View/2292392</guid>
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    <item>
      <title>An emulation oriented method and tool for test of ground traffic control systems at airports</title>
      <link>https://trid.trb.org/View/1989302</link>
      <description><![CDATA[The paper discusses the prospects for the development and implementation of centralized ground traffic control systems at airports. The automatic control system can only work if there is accurate data on the location of mobile objects, which include both vehicles involved in the maintenance of aircraft and the aircraft themselves. In order to develop and test software for any specific centralized control system, the emulation mode should be used, in which the simulation model of the airport transport network works in conjunction with the real control software. In this case, one of the main functions of the simulation model is the generation of data streams that appropriately reflect the processes of movement of objects in the transport network of a specific airport. The paper describes a universal simulation program that allows one to simulate precisely described scenarios for the process in a transport network, which necessitates decision-making at the level of a centralized control system. The movement of objects in the model is accompanied by the recording of their coordinates in the Digital Twin. In this way, real streams of measurement data from various systems for determining the position of moving objects are modeled and stored.]]></description>
      <pubDate>Thu, 21 Jul 2022 11:30:36 GMT</pubDate>
      <guid>https://trid.trb.org/View/1989302</guid>
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    <item>
      <title>Centralized Interlocking for Moving Block Research Project</title>
      <link>https://trid.trb.org/View/1946741</link>
      <description><![CDATA[Transportation Technology Center, Inc. (TTCI) researched and developed concepts for a centralized interlocking (CIXL) system to satisfy the needs of North American railroads. The system leverages the Quasi-Moving Block (QMB) train control method; and provides maintainability and availability benefits. The proposed CIXL system is based on Positive Train Control (PTC) Exclusive Authorities (PTCEAs) that grant movement authority to trains and contain core interlocking data. Within the project, TTCI prepared a technology survey about existing CIXL systems, developed a concept of operations (ConOps) and performed a feasibility assessment for the proposed system.]]></description>
      <pubDate>Sat, 07 May 2022 15:34:18 GMT</pubDate>
      <guid>https://trid.trb.org/View/1946741</guid>
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    <item>
      <title>A dynamic path planning approach for dense, large, grid-based automated guided vehicle systems</title>
      <link>https://trid.trb.org/View/1918329</link>
      <description><![CDATA[Real-time path planning for large, dense grid-based automated guided vehicle (AGV) systems, used for example to sort parcels, is challenging. Most approaches described in the literature are not fast enough for real-time control or are not able to avoid congestion. This paper presents a dynamic approach using a graph-representation of the grid system layout with vertex weights that are updated over time. By means of an extensive discrete-event simulation, the authors show that the proposed path planning approach significantly increases the throughput compared to existing approaches. Furthermore, it enables the recovery from deadlock situations.]]></description>
      <pubDate>Wed, 23 Mar 2022 10:52:00 GMT</pubDate>
      <guid>https://trid.trb.org/View/1918329</guid>
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    <item>
      <title>Centralized Interlocking (CIXL) for Moving Block Research Project</title>
      <link>https://trid.trb.org/View/1849290</link>
      <description><![CDATA[From September 9, 2019, to March 8, 2021, the Federal Railroad Administration (FRA) sponsored Transportation Technology Center, Inc. (TTCI), to develop and analyze a concept for a centralized interlocking (CIXL) system that supports moving block methods of train control, improves overall availability and maintainability, and satisfies the needs of North American railroads. This CIXL system leverages the Quasi-Moving Block (QMB) functional architecture, the intrinsic interlocking performed by Positive Train Control Exclusive Authorities (PTCEA), and train-wayside peer-to-peer communications. Wayside Status Messages (WSM) handle time critical communications from wayside to trains, relaxing the communication demands between the office and the field as compared to the existing centralized interlocking architectures. TTCI assessed the feasibility of the proposed CIXL system in areas such as hardware, software, communications, as well as Reliability, Availability, and Maintainability (RAM) implications. The feasibility assessment indicated that the proposed system should be capable of working with the existing technology as well as improving the overall system maintainability, resulting in increased system availability; however, the benefits could be marginal because no hardware simplification is achieved in the field. Thus, the CIXL system implementation should be analyzed on a scenario-by-scenario basis to identify where the benefits outweigh the costs.]]></description>
      <pubDate>Mon, 17 May 2021 14:58:50 GMT</pubDate>
      <guid>https://trid.trb.org/View/1849290</guid>
    </item>
    <item>
      <title>CBTC system for the monorail in Sentosa Island, Singapore</title>
      <link>https://trid.trb.org/View/1670125</link>
      <description><![CDATA[]]></description>
      <pubDate>Wed, 04 Dec 2019 11:48:23 GMT</pubDate>
      <guid>https://trid.trb.org/View/1670125</guid>
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    <item>
      <title>A comparative study of centralised and decentralised architectures for network traffic control</title>
      <link>https://trid.trb.org/View/1607271</link>
      <description><![CDATA[This paper presents a comparative study of centralised and decentralised architectures for managing urban road network efficiency with consideration of users’ responses and uncertainties with respect to prevailing traffic conditions. The control systems are applied to different network topologies with different levels and spatial distributions of traffic demand. The study reveals that the computationally effective decentralised systems could perform almost as well as the conventional centralised one when users’ responses are taken into account with provision of real-time traffic information. This generates new insight on cooperative transport management with applications of information and communication technology.]]></description>
      <pubDate>Wed, 31 Jul 2019 16:59:39 GMT</pubDate>
      <guid>https://trid.trb.org/View/1607271</guid>
    </item>
    <item>
      <title>Replacement of COMTRAC for the Tokaido/Sanyo Shinkansen</title>
      <link>https://trid.trb.org/View/1634457</link>
      <description><![CDATA[]]></description>
      <pubDate>Tue, 02 Jul 2019 11:30:15 GMT</pubDate>
      <guid>https://trid.trb.org/View/1634457</guid>
    </item>
    <item>
      <title>Centralised versus decentralised signal control of large-scale urban road networks in real time: a simulation study</title>
      <link>https://trid.trb.org/View/1564136</link>
      <description><![CDATA[Recently, signal control strategies with decentralised logic have been developed to tackle the traffic congestion problems of urban road networks. Such strategies aim at network-wide traffic flow efficiency improvement via local actions, thus low design effort and infrastructure investment. This study presents, compares, and evaluates two such innovative approaches: the job scheduling algorithm comprising the local control component of the scalable urban traffic control (SURTRAC) system and the max- or back-pressure algorithm. The approaches are also compared against traffic-responsive urban control (TUC), a well-established strategy with centralised logic. Evaluation is based on the AIMSUN simulation model of the city centre of Chania, Greece. The study results indicate that the TUC and max-pressure retain performance independently of the prevailing traffic conditions, while also being computationally simpler than job scheduling. Both decentralised approaches require frequent (high-resolution) and relatively accurate measurements; on the other hand, TUC, although less demanding in this respect, calls for communication lines between the junction controllers and the central computer. Finally, compared with both decentralised approaches, the TUC provides a signal plan sequence with less excessive differences between each other, thus fewer disturbances to the common network users. Nevertheless, for more comprehensive conclusions, more investigations, including field trials, would be needed.]]></description>
      <pubDate>Tue, 20 Nov 2018 10:17:10 GMT</pubDate>
      <guid>https://trid.trb.org/View/1564136</guid>
    </item>
    <item>
      <title>Simulation Study of Centralized vs Decentralized Approaches to the Signal Control of Large-Scale Urban Networks</title>
      <link>https://trid.trb.org/View/1437977</link>
      <description><![CDATA[Recently, strategies of decentralized logic have been developed to tackle the problem of traffic congestion in urban networks. Such strategies approach the network-wide control problem through local (by junction) actions, but are aimed to improve traffic flow efficiency at network level, with low design effort and infrastructure investment. This paper presents, compares, and evaluates two such innovative approaches proposed in literature. The first, a job scheduling algorithm, comprises the basis of the SURTRAC (Scalable URban TRAffic Control) system, while the second is the known max or back pressure algorithm. The paper compares also their performance against Traffic-responsive Urban Control (TUC),  a well-established strategy of centralized logic, developed to provide coordinated control in large-scale networks. For evaluation purposes, the AIMSUN simulation model of the city center of Chania, Greece, is used. The results of the study indicate that only TUC and max pressure retain their performance independent of the prevailing traffic conditions, being also computationally simpler than job scheduling. As far as the sensing infrastructure is concerned, both decentralized approaches are demanding, as they require frequent and accurate measurements. TUC is less demanding in this respect, but calls for communication lines between the junction controllers and the central computer. Last not least, compared to both decentralized approaches, TUC provides a sequence of signal plans with less excessive differences among each other, thus fewer disturbances to the common network users. Nevertheless, more investigations, including field trials, would be needed for more comprehensive conclusions concerning the strong and weak elements of each approach]]></description>
      <pubDate>Thu, 02 Mar 2017 17:04:03 GMT</pubDate>
      <guid>https://trid.trb.org/View/1437977</guid>
    </item>
    <item>
      <title>Controlling the Corridor</title>
      <link>https://trid.trb.org/View/1422067</link>
      <description><![CDATA[How Amtrak keeps trains and kilovolts where they need to be between Boston and DC.]]></description>
      <pubDate>Tue, 06 Sep 2016 10:25:25 GMT</pubDate>
      <guid>https://trid.trb.org/View/1422067</guid>
    </item>
    <item>
      <title>Electric Energy Control System Simulator for Metro Rail</title>
      <link>https://trid.trb.org/View/1409549</link>
      <description><![CDATA[Urban population in developing countries has been growing phenomenally in the last two decades. Accordingly, the transportation needs are also increasing significantly. In order to meet this requirement, many cities are opting for new modes of transport systems like Monorail, Light Rail Transit (LRT), Mass Rapid Transit (MRT) or expanding their existing transport network to new locations. Safety, reliability and speed are the critical requirements of these transport systems, which are nearly 100% automated in their operation. To achieve this, sophisticated control systems are required and they must be tested extensively under all operating conditions. This calls for a highly automated testing of the control system and this requires a simulator. Though hardware-based simulators can meet some of the testing requirements, they are limited in features, time consuming and more expensive as compared to software-based simulators. This paper describes a software-based simulator for testing the electric energy control system of a metro rail. The electric network with substation and field devices, remote terminal units and the control system constitute the electric energy system of the metro rail. Each of the field devices has different functions and is controlled centrally as well as locally. Monitoring the field devices and knowing their status is essential for the control system to function. The simulator helps in the validation of the electric energy control system by simulating the remote terminal units, the field devices and the communication between them, in a software lab, thus minimizing the time, effort and cost required during commissioning. Using the simulator's various ‘what if’ scenario studies can be carried out in the lab, which helps in the operational decision at critical junctures and in analyzing operational eventualities. The simulator can be easily customized for new projects and offer many more features and advantages.]]></description>
      <pubDate>Tue, 31 May 2016 09:14:08 GMT</pubDate>
      <guid>https://trid.trb.org/View/1409549</guid>
    </item>
    <item>
      <title>On Distributed Traffic Signal Control</title>
      <link>https://trid.trb.org/View/1406236</link>
      <description><![CDATA[Distributed control mechanisms have been studied in past decades in different application areas. Currently, multiagent systems are a popular topic also in intelligent transportation systems (ITS), where numerous approaches to distribution of system intelligence are being tested. One of the main problems in distributed control, however, remains the guarantee of reaching the global optimum - while most of the applications perform sufficiently well, there is no way to tell that they cannot perform even better, or that they may fail under certain operating conditions. Luckily, for certain control paradigms such guarantees may be given. In this paper the authors study two approaches to distributed control, namely distributed LQ control and distributed non-linear control using COBYLA algorithm, and apply them to an urban traffic control scenario. The authors show that the convergence conditions are met and results achieved with distributed control converge to those of centralised control mechanisms.]]></description>
      <pubDate>Mon, 30 May 2016 16:39:07 GMT</pubDate>
      <guid>https://trid.trb.org/View/1406236</guid>
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