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    <title>Transport Research International Documentation (TRID)</title>
    <link>https://trid.trb.org/</link>
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    <language>en-us</language>
    <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>
    <image>
      <title>Transport Research International Documentation (TRID)</title>
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      <link>https://trid.trb.org/</link>
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    <item>
      <title>Tramp ship routing problem considering the implementation of carbon intensity indicator</title>
      <link>https://trid.trb.org/View/2640676</link>
      <description><![CDATA[In 2023, the International Maritime Organization (IMO) formally implemented the mandatory carbon intensity indicator (CII) rating requirements, linking ships' carbon emissions to transport activities. The introduction of CII has significantly impacted shipping companies' fleet operation planning. In this paper, we examine tramp shipping companies' market contract selection and fleet scheduling under the backdrop of CII implementation. By incorporating the CII ship rating requirements into the constraints of a tramp ship routing and scheduling optimisation model, we expand the current research on the tramp ship routing problem to consider new carbon emission regulations. Additionally, a tailored adaptive large neighbourhood search (ALNS) algorithm is designed to provide a solution tool for large-scale instances of the model. Finally, we perform sensitivity analysis experiments on the model using multiple sets of different scales. The multifaceted impact of CII implementation on the fleet operation of shipping companies is discussed based on the experimental results.]]></description>
      <pubDate>Thu, 12 Mar 2026 14:02:13 GMT</pubDate>
      <guid>https://trid.trb.org/View/2640676</guid>
    </item>
    <item>
      <title>A Comparative Analysis of Voyage Charter Parties and Liner Bills of Lading in Maritime Trade</title>
      <link>https://trid.trb.org/View/2598383</link>
      <description><![CDATA[Two types of maritime trade organizations are used to transport goods by sea: tramp shipping and liner trade. The differences between the two are significant and necessitate the use of distinct carriage contracts. This study highlights the key differences between voyage charter parties and liner bills of lading, the main contracts used in tramp and liner shipping, respectively. Tramp shipping involves chartering vessels for specific voyages to transport bulk cargo, with customizable charter parties negotiated between the shipowner and charterer. In contrast, liner shipping follows regular routes and schedules, using standardized liner bills of lading for smaller consignments from multiple shippers. The main distinctions arise from the operational and economic characteristics of each model: voyage charter parties offer greater flexibility with freight rates and cargo requirements, while liner bills provide a uniform framework for efficiency in high-volume shipping. Understanding these differences is essential for stakeholders in maritime commerce, as they influence shipping arrangements, legal responsibilities, and commercial strategies. This analysis aims to clarify the contractual complexities in tramp and liner shipping for better decision-making in maritime trade.]]></description>
      <pubDate>Mon, 20 Oct 2025 09:37:28 GMT</pubDate>
      <guid>https://trid.trb.org/View/2598383</guid>
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    <item>
      <title>A rich model for the tramp ship routing and scheduling problem—Solved through column generation</title>
      <link>https://trid.trb.org/View/2534630</link>
      <description><![CDATA[The authors consider the Tramp Ship Routing and Scheduling Problem (TSRSP) in which they plan routes for a fleet of tramp shipping vessels operating on a combined contract and spot market. Earlier research has been fragmented due to variations in the side constraints studied. Hence they present the first unified model that can handle speed optimization, chartering costs, bunker planning, and hull cleaning. The model is solved by column generation, where the columns represent the possible routes of a vessel, while the master problem keeps track of the binding constraints. The pricing problem is solved efficiently using a time–space graph and several dominance rules. Real-life instances with up to 40 vessels, 35 geographic regions, and four months planning horizon can be solved to optimality in less than half an hour. The optimized routes increase earnings by 7% compared to historical schedules. Furthermore, policy-makers can use the model as a simulation of a rational agent behavior.]]></description>
      <pubDate>Thu, 24 Apr 2025 09:30:37 GMT</pubDate>
      <guid>https://trid.trb.org/View/2534630</guid>
    </item>
    <item>
      <title>Fifty years on maritime transportation</title>
      <link>https://trid.trb.org/View/2478299</link>
      <description><![CDATA[This paper gives a detailed overview of the last 50 years of research in maritime transportation, with special focus on operations research techniques applied to the seaside operations. The authors describe the evolution in industrial, tramp and liner shipping, identify the driving trends, and discuss future challenges.]]></description>
      <pubDate>Tue, 18 Feb 2025 10:56:05 GMT</pubDate>
      <guid>https://trid.trb.org/View/2478299</guid>
    </item>
    <item>
      <title>Cargo selection, route planning, and speed optimization in tramp shipping under carbon intensity indicator (CII) regulations</title>
      <link>https://trid.trb.org/View/2485505</link>
      <description><![CDATA[To mitigate the significant environmental impacts of the shipping industry, the International Maritime Organization (IMO) introduced the Carbon Intensity Indicator (CII), which measures CO2 emissions per unit of cargo-carrying capacity and distance traveled. While the implementation of energy-efficient technologies is crucial for meeting CII regulations, these advancements often entail substantial investment costs. Consequently, optimizing operations has become a more practical short-term approach; however, operational adjustments made solely to comply with CII regulations may also have unintended adverse effects. To address this issue, this research develops a pick up and delivery optimization model for tramp ships, which operate on irregular schedules and routes, to minimize total emissions and costs while complying with CII regulations. The model investigates the combination of cargo selection, route planning, and speed optimization, reflecting the comprehensive and unique characteristics of tramp shipping. The problem is solved using Danzig-Wolfe decomposition and a branch-and-price algorithm, with the CII regulations being met in the pricing problem through a customized heuristic. Numerical results demonstrate that the proposed approach can find optimal or near-optimal solutions within a short time. Various experiments explore the effects of CII regulations on tramp shipping operations, environmental performances, and economic benefits. The results indicate that demand-based CII and stricter CII regulations cause ships to carry fewer cargoes, sail shorter ballast distances, reduce speed, and increase load on board. This ultimately reduces CO2 emissions but also lowers total profits. The findings assist industry stakeholders in complying with stringent environmental regulations and aid policymakers in designing targeted regulatory policies, thereby promoting sustainable maritime transport.]]></description>
      <pubDate>Mon, 27 Jan 2025 11:34:13 GMT</pubDate>
      <guid>https://trid.trb.org/View/2485505</guid>
    </item>
    <item>
      <title>Voyage Estimate and Decision-Making on the Tramp Operation</title>
      <link>https://trid.trb.org/View/2264044</link>
      <description><![CDATA[This paper points out the problems in existing voyage estimate on a tramp operation. By lots of statistics and investigation works, it analyzes the probability of winds within a certain sailing area as well as its influence over a vessel's voyage. The probability distribution of a vessel encountering winds k times in a voyage are testified and the expected per day net revenue value of a voyage is calculated. Then, the paper further puts forward the decision-making problems in a vessel's voyage and analyzes its main influencing factors. Thus, the hierarchy structure and its judgement matrix are established and lead to the adoption of the AHP method on a vessel's voyage. The results of real examples prove to be reliable and realistic.]]></description>
      <pubDate>Mon, 13 Jan 2025 12:02:14 GMT</pubDate>
      <guid>https://trid.trb.org/View/2264044</guid>
    </item>
    <item>
      <title>Voyage charterparty arrangement for river tramp shipping: Green and traditional vessels comparison</title>
      <link>https://trid.trb.org/View/2431863</link>
      <description><![CDATA[Voyage charterparty arrangement (VCA) for river shipping is a common agreement between a shipowner and a charterer regarding the transportation of specific cargoes from one port to another via a tramp vessel. Optimizing VCA with the essential terms such as laytime and sailing speed of the vessel, is a crucial task for both parties to reduce potential disputes and achieve win-win outcomes. This paper models the problem from two perspectives: the VCA negotiation stage and execution stage. Firstly, according to the given probability distribution of port time, the theoretically optimal laytime is obtained by using textbook formulation of newsvendor problems (NVP). On this basis, considering the concerns about the inaccuracy of the given probability distribution and the adjustment measures taken by charterers and shipowners in reality, an integrated adjustment model is constructed to determine the optimal laytime in the VCA negotiation stage. Secondly, taking into account the vessel's uncertain lock crossing time, an operations coordination model with information sharing of the berth plan is established to obtain the optimal sailing speed under a certain confidence level in the VCA execution stage. Finally, a case study of chartering tramp vessels on the Yangtze River validates the applicability and effectiveness of the models proposed in this paper, and some important management insights are derived. The results show that establishing lower optimal speed limits and relatively shorter laytime when signing a contract with the shipowner of green river vessels is reasonable for the charterer. By notifying the shipowner of the berth plan after the green river vessel crosses through the lock, the charterer can avoid higher demurrage costs due to speeding-up. Operations coordination would be mutually beneficial without abusing the contract terms. Compared to traditional river vessels, it's more reasonable to reduce the benefits allocated to charterers from the deceleration of green river vessels by shipowners.]]></description>
      <pubDate>Mon, 30 Sep 2024 08:43:39 GMT</pubDate>
      <guid>https://trid.trb.org/View/2431863</guid>
    </item>
    <item>
      <title>Portside-shipside interaction on shore-power installation: A perspective of tramp shipping deployment</title>
      <link>https://trid.trb.org/View/2404526</link>
      <description><![CDATA[Due to the high initial costs and the uncertain returns of investment, the efficient green technology in shipping industry, shore power (SP), is still in a developmental dark age, especially its installation at bulk terminals and ships. This study examines the factors influencing the SP installation for bulk terminals and ships, elucidates the impacting mechanisms of one party's installation on the investment returns of the other, and reveals the decisive role of fleet operations in the installation decisions of both parties and corresponding carbon emissions. Employing a dataset representing real-world shipping routes and cargo types, the ship-cargo matching and ships' port-of-calls within a planning horizon are optimized with the objective of maximizing the profit of tramp shipping business by taking SP installation and usage cost into account. Portside SP decision-making model is also conducted to estimate the revenue generated by portside SP usage, and guide portside installation decisions based on the cost-benefit ratio. Finally, recommendations are proposed for ship owner, port operator and government to collaboratively navigate through the dark age of SP development, supported by the further discussion regarding fuel-electricity price gap and port loading efficiency.]]></description>
      <pubDate>Tue, 27 Aug 2024 16:08:48 GMT</pubDate>
      <guid>https://trid.trb.org/View/2404526</guid>
    </item>
    <item>
      <title>Route, speed, and bunkering optimization for LNG-fueled tramp ship with alternative bunkering ports</title>
      <link>https://trid.trb.org/View/2378691</link>
      <description><![CDATA[To reduce emissions, shipping companies are deploying eco-friendly ships, like those powered by LNG or methanol. Unlike traditional fuels, LNG bunkering is available at a limited number of ports. At the same time, tramp or bulk ships have fewer ports of call on their shipping lines, which may necessitate LNG-fueled ships sailing to alternative bunkering ports for refueling. The selection of bunkering ports impacts the operating costs of shipping lines due to differences in fuel prices and geographical locations. Moreover, it must factor in ship speed limits to meet loading and unloading schedules. To optimize the shipping route, speeds, and bunkering plan for LNG-fueled tramp ships, the authors develop an arc-based mixed-integer linear programming model with the objective of minimizing total operation costs. Subsequently, the authors propose a leg-based formulation based on the predetermined port call orders. Finally, case studies are conducted to demonstrate the effectiveness and efficiency of the models. Experimental results indicate that the bunkering mode with alternative bunkering ports effectively reduces total operating costs without altering the total voyage time, particularly with substantial differences in fuel prices between ports.]]></description>
      <pubDate>Wed, 29 May 2024 17:14:17 GMT</pubDate>
      <guid>https://trid.trb.org/View/2378691</guid>
    </item>
    <item>
      <title>Optimizing the scheduling scheme for NSR/SCR tramp vessel shipping between Asia and Europe</title>
      <link>https://trid.trb.org/View/2369095</link>
      <description><![CDATA[To optimize the scheduling scheme of tramp vessels between Asia and Europe, considering the opening of the Arctic route, a vessel scheduling management optimization model is developed from the perspective of shipping companies. Based on meeting the shippers' requirements for transportation between Asian and European ports, minimizing the total cost of multi-period operation of tramp vessels, the specific transport scheduling scheme for ships is obtained. The authors found that shipping companies building their Vessels with Ice-breaking Ability (VIA) can reduce the total cost of ships operating Asia-Europe routes throughout the year. Furthermore, in the event of a half increase in fuel prices, opting for Arctic routes during the winter season proves to be more cost-effective for shipping companies.]]></description>
      <pubDate>Fri, 10 May 2024 16:50:45 GMT</pubDate>
      <guid>https://trid.trb.org/View/2369095</guid>
    </item>
    <item>
      <title>Demand Information Distortion in Port Supply Chains</title>
      <link>https://trid.trb.org/View/2282048</link>
      <description><![CDATA[This paper reveals the existence of demand information distortion in port supply chains. First, based on the features of port products and the research work of a supply chain bullwhip by professor H. L. Lee, this paper studies the demand information distortion in a port supply chain involving tramp shipping and liner shipping separately. Then, by analyzing data of the Dalian port throughput of 2015 with a combined forecast model, the authors found the supply capacity of the Dalian port in the future will be much larger than the demand of loading/unloading. Finally, some counter measures are given for ports to eliminate the information distortion of a port supply chain.]]></description>
      <pubDate>Fri, 26 Apr 2024 14:15:19 GMT</pubDate>
      <guid>https://trid.trb.org/View/2282048</guid>
    </item>
    <item>
      <title>Efficiency of Tramp Fleet Operating under the Contracts of Affreightment</title>
      <link>https://trid.trb.org/View/2364666</link>
      <description><![CDATA[The paper considers the vessels operating on carriages of bulk cargoes to get the maximum profit for the shipowner as his main goal. The items in search are the long-term contracts of affreightment with some clauses indicated as indeterminate values, that can be described using a range of values. It leads to a range of voyage indicators. The vessels' deployment for getting the maximum profit depends on the market situation that is to say possible changes in vessels' time-charter rates and freight rates. This paper presents the mathematical model, based on the fleet and volumes of carriages under a set of contracts of affreightment during the due time. It includes the necessity for the commitment fulfilment by owned and time-chartered vessels and takes into account possible changes in freight rates for cargoes carriages. The presented numerical example demonstrates the opportunity for practical implementation of the model.]]></description>
      <pubDate>Fri, 19 Apr 2024 09:48:27 GMT</pubDate>
      <guid>https://trid.trb.org/View/2364666</guid>
    </item>
    <item>
      <title>The effects of waiting times on the bunkering decision for tramp ships</title>
      <link>https://trid.trb.org/View/2359135</link>
      <description><![CDATA[This study explores the influence of uncertain waiting times together with uncertain fuel prices, in the selection of bunker fuel stops for a shipowner engaged in tramp shipping. The authors analyze the stochastic bunkering waiting times in the bunkering optimization problem using scenarios constructed from vessels' Automatic Information System (AIS) records and test their relevance to the bunkering decision. The authors' findings highlight the tradeoff between port efficiency, as characterized by waiting times, and the economic advantages of purchasing bunkers from cheaper port options and finishing the voyage in higher-priced bunker regions. Although the absence of waiting time would have produced similar results in the authors' empirical setup, introducing waiting times altered the dynamics, making a price-attractive port like Piraeus not as attractive when risk-aversion is modeled, particularly given the risk of prolonged waiting.]]></description>
      <pubDate>Wed, 10 Apr 2024 11:38:56 GMT</pubDate>
      <guid>https://trid.trb.org/View/2359135</guid>
    </item>
    <item>
      <title>Tramp ship routing and speed optimization with tidal berth time windows</title>
      <link>https://trid.trb.org/View/2249076</link>
      <description><![CDATA[Tramp shipping companies need to schedule shipping routes and decide on appropriate speeds based on short-term demand. This task differs from traditional vehicle routing problems (VRPs) in that the ship may wait for the tide, which changes with time. The wait time is a nonlinear function of the load, and in this paper, the authors describe this kind of wait as the ship following a tidal berth time windows. Additionally, the speed of the ship affects both the wait time and the sailing cost. This paper proposes a mixed-integer nonlinear programming model to tackle this problem. A branch-and-price framework is applied to solve the model efficiently, decomposing the model into a set partitioning master problem and an elementary shortest path subproblem. A labeling algorithm incorporating ship speed is developed to handle the subproblem, and further enhancements are made by optimizing the speed separately. Computational experiments show the effectiveness and accuracy of the proposed solution approach for large-scale instances. Moreover, considering the tidal time windows allows for exploiting the practical benefits of raising tides, which benefits the tramp shipping industry.]]></description>
      <pubDate>Wed, 27 Sep 2023 09:11:35 GMT</pubDate>
      <guid>https://trid.trb.org/View/2249076</guid>
    </item>
    <item>
      <title>Port call optimization and CO₂-emissions savings – Estimating feasible potential in tramp shipping</title>
      <link>https://trid.trb.org/View/2211771</link>
      <description><![CDATA[The promise of Port Call Optimization (PCO) measures such as Virtual Arrival (VA) for increased fuel efficiency in shipping is emphasized in the literature and professional ranks alike. Despite their envisioned benefits and feasibility, the implementation of such measures has largely remained lacking. Recent studies indicate that the potential of VA on fuel efficiency might be overestimated. In this paper the authors propose a new approach to estimate the fuel efficiency potential of VA based on traffic data from the Swedish tramp shipping sector. The authors' results indicate that the feasible fuel efficiency potential of VA is significantly smaller than what has previously been reported with no discernible benefit to large cohorts of voyages. The authors conclude that further empirical analyses are required for increased accuracy of the estimation of the potential of PCO for increased fuel efficiency in shipping and that more measured approaches in implementation and evaluation of PCO are called for.]]></description>
      <pubDate>Mon, 17 Jul 2023 15:13:23 GMT</pubDate>
      <guid>https://trid.trb.org/View/2211771</guid>
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