Rongfang Liu

Modeling Gate Congestion of Marine Container Terminals, Truck Waiting Cost, and Optimization

As a consequence of the continuing growth of container volume and the introduction of 13,000 containerships carrying 20-ft-equivalent-unit (TEU) containers into major trade routes, the port industry is under pressure to come up with the necessary capacity to accommodate the increasing freight volume. One critical issue is the gate capacity of marine container terminals. Limited gate capacity leads to congestion. The harbor trucking industry operates in a competitive environment, and gate congestion is detrimental to its economic well-being. This paper applies a multiserver queuing model to analyze gate congestion and to quantify the truck waiting cost. An optimization model was developed to minimize the total gate system cost with data from field observations. A case study was applied to analyze gate congestion behavior and the truck waiting cost. The sensitivity of the model is discussed. With optimization, the truck waiting cost can be drastically reduced. Several congestion mitigation alternatives can be derived from the optimization model; the use of a truck appointment system seems to be the most viable way to reduce gate congestion and increase system efficiency.

Analysis of Security System Designs for Ferry Transportation

In detecting threats, particularly explosives, the challenge is to design a system with acceptable detection probability and false-alarm rate that does not unduly inconvenience travelers. Ferry passengers, in particular, are less likely than aviation passengers to tolerate extra delays for extensive scrutiny of themselves or their personal belongings. Similarly, substantial purchase and deployment costs of equipment by ferry owners and operators would not be tenable for small improvements in security. Thus, this paper analyzes different approaches to security and how best to combine detection capabilities and people to enhance ferry transportation security without affecting mobility. Several factors must be considered in choosing practical combinations of detectors to provide the best possible security system. Those factors and their interrelationships are examined within the context of different architectures. Besides the throughput analysis, the manuscript presents a general framework to compare security system designs and implement efficient and effective alternatives for ferry transportation.

Business Model for Commingled Operations of Freight and Non-FRA-Compliant Passenger Rail Services

It is a challenge to develop a business model of commingled operations of freight and non-FRA-compliant passenger rail services because there are no domestic cases of such operations and the number of cases in which freight and light rail transit (LRT) equipment share tracks on a temporal basis of separation is limited. Greater opportunities for commingling may be created, however, because in many domestic cases public passenger transportation and private freight operations share track and there are many proven international experiences with commingled operations of LRT and freight services. This paper identifies and describes the components recommended for inclusion in the business models for both freight railroad operations and public transit agencies for the potential implementation of relevant shared-use operations. These components include shared-use agreements related to costs, capacity, risk sharing, and insurance on the basis of both domestic and international experiences. Building on the experiences of existing shared-use operations and the plans under development, the authors have constructed a business model that can serve as a starting point for future operations.

Improving Rail Station Access with Feeder Bus Network Optimization and Mode Shifts

Because of financial constraints, many transit agencies are trying to balance their budgets and provide an efficient transit network and services. This paper presents an improved model for feeder bus network development problems. The proposed approach consists of three main components: (a) an initial solution generation procedure, (b) a network features determination procedure, and (c) a solution search procedure. The tabu search is used as a metaheuristic method in the solution search procedure to find an optimal solution according to a given set of feasible solutions. The input for the new feeder bus network development problem includes the street network, demands from origins to the suburban rail station, and related parameters. The output demonstrates an optimized feeder bus network system and service frequencies for each route. The results show that the proposed method can be used by transit planners to optimize feeder bus systems that provide access to rail stations and other activity centers.

Tour-Based Time-of-Day Choices for Weekend Nonwork Activities

Research on time-of-day (TOD) choices has predominantly focused on weekday trips or activities, with few studies covering the behavior of TOD choices on weekends. This paper examines TOD choices on weekends using a tour-based approach. A multinomial discrete choice model was calibrated to explore the effects that household and individual socio-demographics have on TOD choice behavior. In light of unique travel patterns on weekends, the authors have combined both Saturday and Sunday into a single travel period, which is then divided into six TOD segments. The methodology is based on the observation that, unlike on weekdays, what individuals do on Saturdays is less likely to be repeated on Sundays with the same TOD pattern. This manuscript demonstrates the application of a tour-based TOD weekend forecast model using the 2001 Atlanta Household Survey data from Georgia. The survey contains detailed travel information on weekends. The study presents the exploratory analysis of weekend travel patterns at both trip-based and tour-based levels in Atlanta. A brief comparison of trip-based and tour-based models is also given. The study validates the suggestion that a tour-based model improves the overall goodness-of-fit of the model and produces a better forecast.

Capacity Analysis for Bifurcated Estuaries Based on Ship Domain Theory and Its Applications

The bifurcated estuary is an important segment of marine transportation systems that are themselves becoming increasingly important. Because of branching channels, the cyclical change of water levels, and sophisticated operating rules in many large bifurcated estuaries, it is often difficult to estimate the traffic capacity and simulate ships’ motions, even though it is critically important for traffic management and efficiency. In recent years, the increasing number of ships that collect and contribute to the Automatic Identification System (AIS) have made it possible to monitor traffic flow along waterways, including bifurcated estuaries. This study developed a typical capacity estimation model based on ship domain theory. By using AIS data collected in the Yangtze River estuary, a typical bifurcated estuary system, the study analyzed various physical characteristics, weather conditions, and vessel characteristics to derive related impacts of each on overall capacity of the bifurcated estuary. Validated with practical observations, the method can be applied to similar estuary channel systems to improve waterway operations and management.

Potential Impact of Housing Policy on Transportation Infrastructure in Chinese Cities

Directive No. 165, a new directive from the Chinese central government–specifically, the Department of Construction–requires that 70% of new residential units be smaller than 90 m2, as of June 1, 2006. The directive raised great concerns after initial confusion and speculation, not only for land developers and consumers but also for urban and transportation planners. The intention of the new policy is clearly targeted to tame ever-rising housing prices and bring affordable housing to average citizens. However, it is questionable whether the policy at its face value can achieve those objectives. The policys effect on land use, urban form, infrastructure, and eventually the housing market is as yet unknown. This paper focuses on the potential effect of the new housing policy on urban infrastructure, particularly transportation. On the basis of the historical urban development in China, Western experience, and current problems and issues encountered by most large metropolitan areas worldwide, the authors caution that the new housing policy may create an unexpected negative effect on transportation infrastructure and make the already congested roadways in most urban areas in China even worse. Some modifications or relevant strategies are needed to achieve the objective of housing affordability while not sacrificing quality of life. It is suggested that connections be made between housing development and urban infrastructure such as transportation, power, water, and comprehensive land use policies to achieve balanced growth and avoid potential social problems.