David Ronen

Ship Routing and Scheduling: Status and Perspectives

The objective of this paper is to review the current status of ship routing and scheduling. We focus on literature published during the last decade. Because routing and scheduling problems are closely related to many other fleet planning problems, we have divided this review into several parts. We start at the strategic fleet planning level and discuss the design of fleets and sea transport systems. We continue with the tactical and operational fleet planning level and consider problems that comprise various ship routing and scheduling aspects. Here, we separately discuss the different modes of operations: industrial, tramp, and liner shipping. Finally, we take a glimpse at naval applications and other related problems that do not naturally fall into these categories. The paper also presents some perspectives regarding future developments and use of optimization-based decision-support systems for ship routing and scheduling. Several of the trends indicate both accelerating needs for and benefits from such systems and, hopefully, this paper will stimulate further research in this area.

Ship routing and scheduling in the new millennium

We review research on ship routing and scheduling and related problems during the new millennium and provide four basic models in this domain. The volume of research in this area about doubles every decade as does the number of research outlets. We have found over a hundred new refereed papers on this topic during the last decade. Problems of wider scope have been addressed as well as more specialized ones. However, complex critical problems remain wide open and provide challenging opportunities for future research.

Cargo ships routing and scheduling: Survey of models and problems

The article discusses briefly the differences between vehicle and ship routing and scheduling as well as the reason for the low interest to ship scheduling in the past. It describes various modes of operating cargo ships and proposes a classification scheme for ship routing and scheduling models and problems. Also provided is a review of ship routing, scheduling and related models. The article breaks the review down into the following categories: transportation system models, liner operations, tramp shipping, industrial operations and other models. A discussion is provided of recent trends in ship scheduling, shortcomings in existing models and requirements from realistic models.

Ship scheduling: The last decade

This work summarizes trends and published research during the last decade in ship scheduling and related problems, and identifies issues which require further investigation. The rapid development of computing power has facilitated optimal solutions to ship scheduling problems which may result in significant economic impact. However, the scarcity of published work in this area indicates the low level of penetration of quantitative models into industrial applications.

The effect of oil price on containership speed and fleet size

The changing prices of bunker fuel open the door for substantial cost savings by adjusting the sailing speed of ships. A large ship may be burning up to 100 000 USD of bunker fuel per day, which may constitute more than 75% of its operating costs. Reducing the cruising speed by 20% reduces daily bunker consumption by 50%. However, in order to maintain liner service frequency and capacity, reducing the cruising speed may require additional ships to operate a route. We construct a cost model that we use to analyse the trade-off between speed reduction and adding vessels to a container line route, and devise a simple procedure to identify the sailing speed and number of vessels that minimize the annual operating cost of the route. Using published data, we demonstrate the potential for large-cost savings when one operates close to the minimal-cost speed. The presented methodology and procedure are applicable for any bunker fuel price.

Chapter 4 Maritime Transportation

Publisher Summary This chapter discusses various aspects of maritime transportation operations and presents associated decision-making problems and models with an emphasis on ship routing and scheduling models. The chapter describes prescriptive operations research (OR) models and associated methodologies, rather than descriptive models that are usually of interest to economists and public policy makers. The ocean shipping industry has a monopoly on transportation of large volumes of cargo among continents. Pipeline is the only transportation mode that is cheaper than ships for moving large volumes of cargo over long distances. Maritime transportation is the backbone of international trade. The volume of maritime transportation has been growing for many years and is expected to continue growing in the foreseeable future. Maritime transportation is a unique transportation mode possessing characteristics that differ from other modes of transportation and requires decision support models that fit the specific problem characteristics. Maritime transportation poses a wide variety of challenging research problems, the solutions to which have high potential to improve economic performance and increase profitability in the highly competitive arena.

SCHEDULING SHORT-TERM MARINE TRANSPORT OF BULK PRODUCTS

A multinational company uses a personal computer to schedule a fleet of coastal tankers and barges transporting liquid bulk products among plants, distribution centres (tank farms), and industrial customers. A simple spreadsheet interface cloaks a sophisticated optimization-based decision support system and makes this system useable via a varity of natural languages. The dispatchers, whose native language is not English, and some of whom presumably speak no English at all, communicate via the spreadsheet, and view recommended schedules displayed in Gantt charts both internationally familiar tools. Inside the spreadsheet, a highly detailed simulation can generate every feasible alternate vessel employment schedule, and an integer linear set partitioning model selects one schedule for each vessel so that all loads and deliveries are completed at minimal cost while satisfying all operational requirements. The optimized fleet employment schedule is displyed graphically with hourly time resolution over a planning horizon of 2-3 weeks. Each vessel will customarily make several voyages and many port calls to load and unload products during this time.

Marine inventory routing: shipments planning

This paper addresses a shipments-planning problem faced by producers of large volume liquid bulk products. Producing origins with limited tank storage capacity supply multiple products by ships (or barges) to consuming destinations that also have limited storage capacity. Timing, origin, destination, and product quantities of shipments have to be determined in a manner that minimizes costs and does not violate storage capacity constraints at both ends (neither stopping production at the origins, nor running out of stock at the destinations). A mixed integer-programming model is used to derive cost effective solutions within a few minutes. A cost-based heuristic algorithm is used to assure that acceptable solutions are obtained quickly.

PERSPECTIVES ON PRACTICAL ASPECTS OF TRUCK ROUTING AND SCHEDULING

Abstract Truck routing and scheduling problems are differentiated from other vehicle routing and scheduling problems and a classification scheme for the former ones is outlined. Many characteristics of practical truck routing and scheduling problems are listed and several aspects are discussed, among them are: soft constraints, demand variability, multiple objectives, complex cost functions, and alternate solution approaches with their potential for solving practical problems. It is suggested that cost-based interactive heuristics coupled with graphical presentation of solutions may be the right method to deal with the more complex practical problems. Some basic generic heuristics are suggested and important software design and acquisition considerations are presented.

Dispatching Petroleum Products

Petroleum products are distributed worldwide from refineries and lube plants to retail outlets and industrial customers. Proper dispatching of shipments of such products, packaged and in bulk, may result in significant transportation and inventory cost savings. This work examines the variety of operational environments which exist in dispatching petroleum products, and the operations research tools used by oil companies to dispatch such products. In addition, it identifies gaps where additional research is needed.