苏州轨道交通运营人才培养策略

城市轨道交通建设的最终目标是投入运营,为公众提供高效的出行服务,因此,与之相适应的,必须有一支高素质的运营人才队伍作保证。文章结合苏州轨道交通运营现状,进一步分析探索城市轨道交通企业运营人才的培养方法和途径。     

Reducing emissions through speed optimization in supply vessel operations

This paper examines how optimizing sailing speeds can reduce supply vessels emissions in the upstream supply chain to offshore installations. We introduce several speed optimization strategies to be used in construction of periodic vessel schedules. The strategies consider vessel waiting times before the start of service at installations and at supply base. Tests carried out on real instances from Statoil’s activities on the Norwegian continental shelf indicate that a 25% emissions and fuel cost reductions can be achieved without fleet size increase.     

A transit ridership‐revenue model

The paper outlines the theoretical underpinnings of an urban mass transit revenue and ridership model designed to provide medium term forecasts of future trends in situations of data sparsity. The specific example laid out in the paper relates to the Greater Vancouver Regional District but the framework is of general applicability. Much of the informational input at the initial stage is of a general kind and details of the specific transit system and local area are of the sort which should be readily available to most urban authorities. The model developed is designed for use on a desk‐top micro‐computer and offers an inter‐active method of forecasting. The operator has the facility to both consider fare policy sensitivity and review alternative scenarios about future trends in exogenous factors. A selection of forecasts developed for the GVRD is provided to reveal the main features of the approach.     

Analysis of real-time control strategies in a corridor with multiple bus services

Control strategies have been widely used in the literature to counteract the effects of bus bunching in passenger‘s waiting times and its variability. These strategies have only been studied for the case of a single bus line in a corridor. However, in many real cases this assumption does not hold. Indeed, there are many transit corridors with multiple bus lines interacting, and this interaction affects the efficiency of the implemented control mechanism.This work develops an optimization model capable of executing a control scheme based on holding strategy for a corridor with multiple bus lines.We analyzed the benefits in the level of service of the public transport system when considering a central operator who wants to maximize the level of service for users of all the bus lines, versus scenarios where each bus line operates independently. A simulation was carried out considering two medium frequency bus lines that serve a set of stops and where these two bus lines coexist in a given subset of stops. In the simulation we compared the existence of a central operator, using the optimization model we developed, against the independent operation of each line.In the simulations the central operator showed a greater reduction in the overall waiting time of the passengers of 55% compared to a no control scenario. It also provided a balanced load of the buses along the corridor, and a lower variability of the bus headways in the subset of stops where the lines coexist, thus obtaining better reliability for all types of passengers present in the public transport system.     

“This train is without a destination”: a cost benefit analysis of the retention of railway services — the Penistone line

The paper undertakes a cost‐benefit analysis of a disinvestment using readily available data and demonstrates that a relatively straightforward yet systematic approach can provide useful input to the decision‐making process. Despite various assumptions necessitated by the analysis, it is argued that the net benefits of the railway line retention are unlikely to be significantly sensitive to their variation within feasible limits. The most significant component in the analysis is seen to be the operative costing system and it is argued that this should be revised.     

A simulation model for gate operations in multi-purpose cargo terminals

ABSTRACT

A multi-purpose cargo terminal in a seaport contains necessary infrastructure to handle different types of cargo, such as container, dry bulk, general bulk, and Ro-Ro. Since such terminals generally have dedicated areas and equipment for different types of cargo, berth, and yard operations for each type of cargo can be considered separate. On the other hand, trucks that carry all types of cargo use the same gate structure to enter and leave the terminal. Therefore, a method to superimpose the traffic that is caused by different types of cargo is needed for the planning of gate investments and operations. Consequently, this paper has developed a simulation model for a multi-purpose terminal to estimate the gate traffic and determine the necessary gate infrastructure, so that it can be used as a decision support tool for terminal planners and operational managers.     

In Search of the Link between Ship Size and Operations

Abstract

Since 1990s the liner shipping industry has faced a period of restructuring and consolidation, and been confronted with a continuing increase in container vessel scale. The impact of these changes is noticeable in trade patterns, cargo handling methods and shipping routes, in short ‘operations’. After listing factors influencing size, growth in container ship size is explained by economies of scale in deploying larger vessels. In order to quantify economies of scale, this paper uses the liner service cash flow model. A novelty in the model is the inclusion of +6000-20-foot Equivalent Unit (TEU) vessels and the distinction in costs between single and twin propeller units on ships. The results illustrate that scale economies have been – and will continue to be – the driving force behind the deployment of larger container vessels. The paper then assesses the link between ship size and operations, given current discussions about the increase in container vessel scale. It is found that (a) ship size and operations are linked; (b) optimal ship size depends on transport segment (deep-sea vs. short-sea shipping, SSS), terminal type (transhipment terminals vs. other terminals), trade lane (East-West vs. North-South trades) and technology; and (c) a ship optimal for one trade can be suboptimal for another.     

Can long-haul low-cost airlines be successful?

A key question is whether the very successful, largely short-haul LCC business model can work over long-haul sectors? This paper compares the cost and other advantages of LCCs and evaluates how far they might be applied to long-haul sectors. It is estimated that cost advantages might be much lower than the 50-60% on short-hauls. Other factors such as the adoption by network airlines of some LCC features and their likely competitive response, the limited potential for market stimulation, the need for dense markets and feed traffic all combine to cast doubt on the widespread establishment of the business model for long-haul flights.     

Approximation algorithms for the bid construction problem in combinatorial auctions for the procurement of freight transportation contracts

Trucking companies (carriers) are increasingly facing combinatorial auctions conducted by shippers seeking contracts for their transportation needs. The bid valuation and construction problem for carriers facing these combinatorial auctions is very difficult and involves the computation of a number of NP-hard sub problems. In this paper we examine computationally tractable approximation methods for estimating these values and constructing bids. The benefit of our approximation method is that it provides a way for carriers to discover their true costs and construct optimal or near optimal bids by solving a single NP-hard problem. This represents a significant improvement in computational efficiency. We examine our method both analytically and empirically using a simulation based analysis.