bluuebunny/crossref_metadata_2025 huggingface dataset:
Refinement of Drivers' Visibility Needs during Wet Night Conditions
Authors: Gibbons Ronald B. , Williams Brian , Cottrell Benjamin
Published: October 2012

The purpose of this project was to develop a specification for the minimum retroreflectivity of pavement markings in wet nighttime conditions. For this specification to be established, the performance of four retroreflective pavement marking materials in wet night conditions was evaluated. The performance of the pavement markings was evaluated by driver participants under simulated rain conditions with a protocol similar to that of studies that had already been performed at the Virginia Tech Transportation Institute, Virginia Polytechnic Institute and State University. The performance of the markings was verified on the basis of the participants' ability to detect the end points of the markings in both rainy and clear conditions. This investigation reached the following conclusions: (a) The materials developed over recent years showed an improved performance over those tested previously. (b) The log-linear relationship found previously was functional for the data provided. Two models were developed. The model with no intercept provided a more constrictive boundary at low levels of retroreflectivity. (c) A retroreflectivity value above 250 millicandelas per square meter per lux (mcd/m2/lx) provided limited return in terms of detection distance. (d) A specification limit of 150 mcd/m2/lx provided adequate visibility for 55 mph in dry conditions and 40 mph in wet conditions with standard dry retroreflectivity measurements and 1 in./h measurements for wet conditions. This value should be the minimum maintained over the life of the marking. (e) The retroreflectivity specifications for a white and a yellow material should be equal. (f) The rumble stripe showed a significant recovery time improvement over the other tested materials. A minimum retroreflectivity of 150 mcd/m2/lx for white and yellow pavement markings in both dry and wet nighttime conditions is recommended.
Service Life Analysis and Maintenance Program of Pavement Markings in Thailand
Authors: Lertworawanich Ponlathep , Karoonsoontawong Ampol
Published: October 2012

Pavement markings are one of the most important highway assets. Good pavement markings provide good visibility for traffic, whereas poor pavement markings can adversely affect traffic operations on highways. However, a limited amount of research has been conducted on the effects of working conditions on the service life of pavement markings. This paper presents duration models for retroreflectivity of thermoplastic pavement markings in Thailand. This approach allows the service life of pavement markings to follow probability distributions in which model parameters are assumed as a function of relevant independent variables such as traffic volumes. The maximum likelihood estimation technique was used to estimate means and standard errors of the model parameters. Retroreflectivity data of thermoplastic pavement markings were collected from the eastern highway network of Thailand, which consists of more than 5,000 km of highways in various traffic conditions. The analysis results showed that traffic volumes had negative effects on the service life of the pavement markings. This paper proposes a preemptive goal program for approximating required budgets to ensure the maintenance of the percentages of good condition pavement markings over the planning horizon. The first-priority goal is to maintain the percentage of control sections that are in good condition, and the second-priority goal is to minimize total maintenance costs. In the illustrative example, the inconsistency between the Thailand Department of Highways' specifications and field practices caused estimated required annual budgets and the deterioration of pavement markings to greatly fluctuate over the planning period. For more consistency between specification and field practice, the proposed models will be applied in a pavement marking management system.
Field Test of Organic Deicers as Prewetting and Anti-Icing Agents for Winter Road Maintenance
Authors: Fu Liping , Omer Raqib , Jiang Chaozhe
Published: October 2012

Salts, in both solid and liquid forms, are used in winter road maintenance because of their effectiveness in breaking and preventing the bonding of snow and ice to road surfaces. Because of the detrimental effects of salt on infrastructure and the environment, many alternative materials are being tested for snow and ice control during winter. This paper summarizes the results of field tests that compared two beet molasses–based materials with regular salt and salt brine when used as prewetting and anti-icing agents. The performance comparison was based on more than 100 h of friction readings along with high-resolution image data collected over nine snow events. Application rates, test route, and comparison methodology along with experimental results, recommendations, and potential for future research are also presented.
Evaluation of Performance of Automatic Vehicle Location and TowPlow for Winter Maintenance Operations in Wisconsin
Authors: Santiago-Chaparro Kelvin R. , Chitturi Madhav , Szymkowski Todd , Noyce David A.
Published: October 2012

Winter maintenance operations are a major expense for state departments of transportation located within the Snow Belt of North America. Winter maintenance-related expenses for 2005 through 2010 ranged from $46 million to $87 million per year for state highways in Wisconsin. During the past two winters, the Wisconsin Department of Transportation implemented TowPlow and automatic vehicle location (AVL) technologies to optimize winter maintenance operations. A TowPlow is a plow that is attached to a regular plow truck to increase the snow removal capacity. AVL is a combination of systems capable of monitoring the location of a vehicle, material application rates, and road conditions from a central location. In this paper, qualitative and quantitative evaluations are presented for these two technologies. Findings from both evaluations showed that the implementation of these technologies would result in potential cost savings resulting from lower salt usage (AVL) and more efficient operations (TowPlow). The use of a TowPlow to perform the same task as a regular plow truck resulted in 32% to 43% operational cost savings. Implementation challenges, maintenance issues, and reduction in salt usage by counties that implemented AVL were evaluated. Implementation of AVL resulted in about 6% savings in salt usage from increased plow operator compliance with guidelines. When only the savings in salt usage and none of the intangible benefits were considered, the benefit–cost ratio values ranged from 1.05 to 1.89 depending on the cost of salt and percentage of reduction in salt usage.
Laboratory and Field Evaluation of Anti-Icing Strategies
Authors: Cuelho Eli , Harwood Jason
Published: October 2012

Departments of transportation use a variety of strategies to maintain roadways effectively during winter while considering a number of factors, such as level of service, cost, infrastructure and environmental impacts, equipment, and weather. The impacts of chemicals on infrastructure, vehicles, and the environment have motivated the State of California to reduce salt usage on highways and to move toward anti-icing strategies, which typically use fewer chemicals to achieve effective results. However, a lack of established recommended dispersal rates, laboratory studies to verify field studies, and an understanding of the science associated with anti-icing principles has slowed full implementation of anti-icing strategies in California. This research effort focused on synthesizing available information regarding winter maintenance best practices and establishing a set of preliminary guidelines to implement anti-icing strategies in California. A qualitative and quantitative evaluation of the performance of five typical anti-icing chemicals was conducted. Performance measures included the temperature at which the snow–pavement bond failed, friction of the pavement surface after snow removal, and snow–pavement bond strength. In general, anti-icing methods used in the laboratory and in full-scale controlled field tests reduced the effort required to remove compacted snow from the pavement surface and improved pavement surface friction after plowing when compared with untreated pavements. A set of guidelines was developed to initiate implementation of anti-icing practices in California. Further assessments are necessary to optimize this methodology on the basis of specific weather conditions and application methods.
Parameters of Time Headway Distribution as Performance Indicators of Motorway Traffic and Driver Behavior
Authors: Habtemichael Filmon G. , de Picado Santos Luis , Faouzi Nour-Eddin El
Published: October 2012

Understanding traffic characteristics and the behavior of drivers is crucial for motorway traffic managers and roadway operators. Time headway provides the comprehensive image of traffic stability and driver behavior under a wide range of traffic contexts. This paper discusses how traffic stability and driver behavior are affected by precipitation of several intensities. Mathematical modeling and comparison of time headway distributions under dry weather, light rain, medium rain, and heavy rain intensities were conducted with a gamma-generalized queuing model (gamma-GQM), and the trend of variations of the gamma-GQM parameters was analyzed. Relationships between the model parameters, traffic stability, and driver behavior were established when the parameters were plotted against hourly traffic volumes and average densities. The trend of variations of the four model parameters had a consistent distribution pattern under dry weather conditions. The variations of gamma-GQM parameters were slightly disturbed during light and heavy rainfall intensities. During medium rain conditions, the variation of gamma-GQM parameters was exceedingly disturbed. The results indicated that traffic characteristics and driver behavior were more inconsistent under medium rain than with all other intensities. The willingness of drivers to accept any kind of risk in following a vehicle largely varied during medium rain conditions. Speed variability provided an extra insight into the drivers' perception at different levels of rainfall intensities.
Performance Evaluation for Rural Two-Plus-One–Lane Highway in a Cold, Snowy Region
Authors: Munehiro Kazunori , Takemoto Azuma , Takahashi Naoto , Watanabe Masayoshi , Asano Motoki
Published: October 2012

Hokkaido, Japan, is a cold, snowy island where winter lasts for approximately 5 months, from November to March. Road surfaces are usually dry, but frequently covered with compacted snow. A measure to improve existing two-lane highways to two-plus-one (2+1) lane highways by installing an auxiliary lane has been introduced to offer a better quality of service to road users. A sensitivity analysis was undertaken with a traffic flow microsimulation program, SIM-R, to evaluate the effectiveness of 2+1-lane highway sections, which were built by adding an auxiliary lane to rural two-lane highways, in a cold, snowy region. The road surface conditions under analysis were dry and covered with compacted snow. The hourly traffic volumes were changed from 100 to 1,000 vehicles per hour. Evaluation indicators were the average travel speed, the percentage of following vehicles, and the density of following vehicles. The results showed that the average travel speed decreased, the follower percentage increased, and the follower density increased as the hourly traffic volumes increased. Moreover, the road performance decreased on the road covered with compacted snow compared with the dry road. The installation of an auxiliary lane at certain intervals was also found to improve the level of service for two-lane highways on both the dry road and the road with compacted snow.
Modeling the Impact of Inclement Weather on Freeway Traffic Speed at Macroscopic and Microscopic Levels
Authors: Zhao Yunjie , Sadek Adel W. , Fuglewicz Daniel
Published: October 2012

Inclement weather conditions, such as snowy and icy conditions, could have major impacts on driver behavior and on the performance of surface transportation systems. Recently, researchers have had an increased interest in understanding this impact better as well as in modeling it. This study contributes to the emerging literature in the impact of snowy and icy conditions on traffic and driver behavior by modeling the impact of inclement weather on freeway traffic speed, at both the macroscopic and microscopic levels, with data from Buffalo, New York. At the macroscopic level, freeway speed data observed on a Buffalo section of the New York State Thruway were correlated to a set of weather indices introduced by the study; the result was a regression model that could be used to estimate the average freeway speed as a function of weather conditions. At the microscopic level, the study was the first attempt to calibrate a cellular-automata traffic simulation model, specifically, the TRANSIMS model, to inclement weather (i.e., snowy) conditions. For the calibration of TRANSIMS, a vehicle equipped with a Global Positioning System collected second-by-second vehicle dynamics information during both normal and snowy weather conditions. The collected information was the basis for the adjustment of several of the TRANSIMS model parameters. The adjusted parameters enabled the model to closely replicate observed traffic flow parameters at both the macroscopic and microscopic scales.
Simulation-Based Scheduling of Mutually Exclusive Projects with Precedence and Regional Budget Constraints
Authors: Wang Shiaaulir , Schonfeld Paul
Published: October 2012

This paper presents an improved scheduling model for waterway projects that can consider several complicating factors: (a) multiple project alternatives at each location, of which only one may be selected per location; (b) multiple budget sources or regional funding constraints; and (c) constrained precedence relationships between projects. To solve the problem, a simulation-based optimization model that uses simulation to evaluate alternative project schedules is developed. A genetic algorithm is also developed to solve this large investment optimization problem efficiently by means of some prescreening rules that reduce the number of simulated alternatives. The mutually exclusive alternatives at each location allow joint optimization of the sizing and timing of improvements. The multiple budget constraints realistically reflect actual funding practices, but considerably complicate the problem because project sequencing no longer uniquely determines the schedules and projects that may now be funded concurrently. The numerical example shows how the additional factors considered here can be properly incorporated into the analysis and how the quality and reliability of results from such a relatively complex model can be verified.
Supporting Secure and Resilient Inland Waterways
Authors: Campo Matthew , Mayer Henry , Rovito Jennifer
Published: October 2012

The U.S. Department of Homeland Security's National Infrastructure Protection Program presents sector-specific planning objectives for protecting the nation's critical infrastructure and key resources. In concert with this objective, researchers at the University of Arkansas and Rutgers University are developing a prototype decision support system that integrates geographic information systems and freight movement models to provide a framework for cargo prioritization and off-loading during a sudden catastrophic closure of the national inland waterway. The project seeks to develop (a) a fundamental understanding of the resiliency of inland waterway transportation systems and the interdependence within and between transportation system components and (b) a decision system that will allow public and private parties to respond quickly to catastrophic waterway events. Researchers reviewed public data, published literature, and aerial imagery to ascertain terminal characteristics indicative of a potential for transferring barge cargo from the inland waterway to freight rail systems. A preliminary framework for assessing terminal suitability for intermodal transfer during a sudden catastrophic closure was developed. Findings suggest that the geographic dispersion of terminals and their commodity-specific nature often limit off-loading operations at certain terminals to their designated commercial purpose only. Other configurations could allow for the off-loading of additional commodities at these terminals. Consideration of alternative terminal uses during a sudden catastrophic closure requires a detailed understanding of terminal capabilities beyond historical commercial use. An investigation of alternative capabilities should be undertaken at each link in the interdependent inland marine and surface transportation systems to develop an effective decision-making framework.
Robust Optimization Model for Liner Ship Fleet Planning with Container Transshipment and Uncertain Demand
Authors: Wang Tingsong , Meng Qiang , Wang Shuaian
Published: October 2012

This paper studies a problem of liner ship fleet planning with container transshipment under uncertain demand for container shipments. Generally, this problem can be solved with an optimization model to minimize or maximize the expected value of a key variable, such as cost or profit. However, such models do not consider the variance (namely, the risk), another issue of great concern to decision makers. Therefore, this paper aims to develop a robust optimization model in which both expected value and variance are considered simultaneously. By adjusting the penalty parameters of the robust optimization model, decision makers can determine an optimal plan for liner ship fleets (including decisions about fleet design and deployment) to maximize total profit under different container shipment demand scenarios while simultaneously controlling variance. The robustness and effectiveness of the developed model are demonstrated with numerical results.
Performance Evaluation for Implementation of Port Community System
Authors: Tsamboulas Dimitrios , Moraiti Panayota , Lekka Anna M.
Published: October 2012

The shipping and port industry must respond to a new reality that has been created by the continuing growth of world trade and the emergence of global operators. This combination has resulted in increased demand for seaports and their related services while they are divided into competing nodal points in the entire global logistic chain. To improve their competitive positions, many ports have begun developing and implementing the port community system (PCS), which constitutes an electronic platform that connects multiple systems operated by a variety of organizations that constitute the seaport community and is believed to be a significant contributing factor to a more efficient movement of cargo across international borders. Related research on the integration of PCSs has only recently started to develop. To this end, this paper proposes a methodology to evaluate port performance changes with the introduction of PCS, which, under a competitive environment is of significant importance to port management. The proposed evaluation methodology introduces, among others, key port performance indicators to account for system implementation. An application of the methodology is carried out for the real case of a port that is kept anonymous to maintain confidentiality. The methodology can constitute an effective decision-making tool for port managers, as well as regional and national authorities, to perform port improvement analysis, encouraging these to be proactive in PCS development—ultimately leading to efficiency, productivity, and competitiveness gains.
Impacts of Panama Canal Expansion on U.S. Greenhouse Gas Emissions
Authors: Bittner Jason , Baird Timothy , Adams Teresa
Published: October 2012

International shipping is a significant contributor to global climate change, accounting for approximately 3.3% of global carbon dioxide (CO2) emissions across all sectors. The expansion of the Panama Canal, scheduled to open in 2014, will improve available all-water routes for trade between the eastern United States and Asia, creating opportunities for both lower emissions and lower costs. The authors used data from the import and export projections of the FHWA Freight Analysis Framework 3 database to estimate the canal's impact on shipping emissions with and without the expansion project. The expansion is expected to reduce annual CO2 emissions of U.S. East Coast–Asia trade by 1.4 billion kg in 2025, a per ton reduction of 2.69%. Along with design and operational improvements, the efficiencies created by increased opportunities for use of all-water routes and large vessels are expected to have a small but beneficial impact on greenhouse gas reduction efforts in international shipping.
Microscopic Approach to Evaluate Energy Consumption and Emissions from Ships
Authors: Ciuffo Biagio , Miola Apollonia
Published: October 2012

Maritime transport plays a central role in the debate about the sustainability of the transport sector. Analyses suggest that air emissions from shipping account for a significant portion of total emissions, affect air quality, and contribute to climate change and human health problems. The existing trend suggests that the situation will worsen. These results, though affected by obvious uncertainties, highlight the urgent need to take action. Harmful environmental impacts are controlled primarily through legislation prohibiting the use of certain substances, setting limits on emissions, and enforcing certain technical standards. However, the basis for designing effective policy instruments to abate air emissions is finding reliable estimates of those emissions. For the shipping sector, a debate continues about the most appropriate way to achieve its air emissions estimate. This paper contributes to this debate by proposing a new methodology that applies some of the available theories from the naval design scientific field to derive a microscopic analytical formulation of the energy produced and consumed by a ship during its trips. The methodology proposed is applied to evaluations of potential savings in energy and emissions by adjusting the speed–acceleration profile of ships in port. Results achieved confirm the power of the methodology and open its application to other case studies. They also highlight an aspect usually neglected in the literature: the impact of ships' activities in port on the environment. The simple exercises performed show clearly the relevance of the issue. They are also able to show that better management of ships' movements in port may produce significant environmental benefits.
Economic Analysis of Impacts of Sea Level Rise and Adaptation Strategies in Transportation
Authors: Lu Qing-Chang , Peng Zhong-Ren , Du Rongyi
Published: October 2012

Although the causes of the sea level rise (SLR) are hotly debated, almost no disagreement exists that sea levels will continue to rise. The SLR is likely to have significant impacts on coastal transportation infrastructure. Adaptations in response to the SLR are in urgent need. Facing various adaptation strategies, decision makers need information on the impacts of different SLR scenarios as well as the economic trade-offs of various adaptation strategies. This research attempts to quantify the economic impacts of the SLR as well as the costs and benefits of adaptation strategies by using cost–benefit analysis at the local level. Hillsborough County, Florida, is used as a case study, and two projected scenarios for the SLR are applied to it. Light detection and ranging data, parcel land use data, and transportation network data for the county are employed to estimate the impacts of the two scenarios. Three adaptation strategies are suggested to the proposed SLR scenarios. Then cost–benefit analysis is conducted for each strategy under the two scenarios that consider the impacts of both direct inundation costs and indirect travel time costs. On the basis of the present values of the net benefits in the proposed strategies, managed retreat with critical infrastructure protection is the best adaptation strategy for the SLR in the long run and the length of shoreline protection is the most sensitive to the net benefits.
Challenges of Vessel General Permit
Authors: Hsieh Hsin-Neng , Rodriguez Paul , Marhaba Taha
Published: October 2012

The U.S. Environmental Protection Agency (EPA) issued the Vessel General Permit (VGP) for discharges incidental to the normal operation of vessels on February 5, 2009, under the Clean Water Act. This permit set forth requirements for most vessel discharges within 3 nautical miles of the U.S. shore. The requirements include filing for a notice of intent, meeting VGP effluent limits, inspecting and monitoring, record keeping, and reporting. To understand the impact of this permit, data were solicited from EPA. On the basis of the results of the analyzed data and discussion with individuals from the maritime industry and various government agencies, this paper discusses five aspects of challenges that the VGP may encounter: EPA's roles, states' additional requirements, onshore facilities, compliance issues, and economic impact.
Analysis of Current and Emerging Drayage Practices
Authors: Smith Daniel , Harder Frank , Huynh Nathan , Hutson Nathan , Harrison Robert
Published: October 2012

The focus of this paper is port drayage, which involves the transport of containers between a port terminal and an inland point by truck. The paper has two purposes. The first is to identify inefficiencies in port drayage and quantify their economic and environmental impacts. The uniqueness of this study is its use of verifiable data provided by terminal operators and drayage companies rather than survey data from drayage drivers and limited field-based observations. The second purpose is to discuss the recent major change within the drayage industry to abandon the carrier-provided chassis model that has been in place for more than 50 years. To this end, the emerging trucker-supplied chassis model is analyzed.
Dispatch Problem of Automated Guided Vehicles for Serving Tandem Lift Quay Crane
Authors: Xing Yao , Yin Kai , Quadrifoglio Luca , Wang Bruce X.
Published: October 2012

New quay cranes (QCs) have been designed to increase terminal productivity by lifting more containers simultaneously. But QC productivity relies on efficient cooperation with the vehicles carrying the containers. This paper investigates the synchronization scheduling problem between the automated guided vehicles and these new QCs. The problem is formulated as a mixed integer linear programming model. Because of the problem's complexity, a heuristic dispatch rule is proposed for practical purposes. Then, to balance the computation time and the quality of the solution, a neighborhood search method is designed by investigating the working sequences of automated guided vehicles. Numerical experiments show that both heuristics obtain good solutions within extremely short times and that the neighborhood search method generally performs better in relation to the objective value.
Schedule Template Design and Storage Allocation for Cyclically Visiting Feeders in Container Transshipment Hubs
Authors: Lee Der-Horng , Jin Jian Gang , Chen Jiang Hang
Published: October 2012

This paper studies the management of transshipment flows in a container terminal. Management consists of designing a visiting schedule template for feeder vessels and determining storage locations for transshipment containers. A mixed integer programming formulation is developed; it includes the objective of minimizing both the total distance traveled by transshipment flows between quayside and storage yard and the workload imbalance in time. To solve the problem, an algorithm is devised on the basis of Lagrangian relaxation to find near-optimal solutions within short computational times. Numerical experiments are conducted to assess (a) the effectiveness and efficiency of the algorithm and (b) the benefit from adjusting feeder visiting schedule.
Empirical Analysis of Resiliency of Terminal Operations for Roll-On–Roll-Off Vessels
Authors: Saurí Sergi , Morales-Fusco Pau , Toledano Maria , Martín Enrique
Published: October 2012

Regular maritime lines with roll-on–roll-off vessels must offer a reliable service without substantial cost increases to be competitive. Port terminals need to respond quickly to any disturbance and return to a smooth operational state in a minimum amount of time (resilient terminals). In this paper, a complete taxonomy of the disturbances affecting the operational processes in a roll-on–roll-off terminal is introduced together with a system able to assess the performance of any measure used to mitigate those disturbances. This study is based on an overview of the existing literature on the topic, a detailed diagram of the operational processes of the terminal, and a set of interviews with the staff involved in the processes occurring in the terminal, along with field measurements. The main vulnerabilities are identified, and possible corrective and preventive measures are emphasized.
Analyses and Implications of Accidents in Singapore Strait
Authors: Qu Xiaobo , Meng Qiang , Li Suyi
Published: October 2012

This paper aims to estimate the lower and upper bounds of the number of accidents that have occurred in the Singapore Strait over the past 10 years on the basis of two maritime accident databases: Global Integrated Shipping Information System and Lloyd's List Intelligence. After an evaluation of the incompleteness of these two databases, a novel and tangible method is proposed to estimate the lower and upper bounds of the number of accidents by using Bayesian analysis under mild assumptions. This method produces the following three important results. First, the annual maritime accident occurrence frequency in the Singapore Strait ranges from 17.6 to 33.0; that is, less than 0.005% of vessels could be involved in an accident when passing through the Strait. Second, the reporting performances of both maritime accident databases to the Singapore Strait are less than 62.5%. In other words, more than 37.5% of maritime accidents are not included in the database. Third, ship collisions account for more than 50% of all types of accidents; this result indicates that a high priority should be assigned to reducing the occurrence of ship collisions by enhancing the navigational systems in the Singapore Strait.
Application of Fuzzy Logic to Safety Risk Assessment of China's Maritime Passages
Authors: Huang Dao-Zheng , Hu Hao , Li Yi-Zhou
Published: October 2012

The maritime system has a high level of uncertainty, which makes it difficult to assess its safety. This paper proposes an improved formal safety assessment (FSA) method based on fuzzy logic and employing if–then rules, which model the qualitative aspects of human knowledge and reasoning processes. A fuzzy expert system is then designed to address FSA's risk assessment step. An investigation is performed to gain expert knowledge, which is essential to building this system. An example that assesses the safety of Chinese maritime passages is used to illustrate the methodology. The method is effective in the solution of problems with high uncertainty. Finally, suggestions are given to enhance the level of safety.
Dynamic Fuzzy Logic Model for Risk Assessment of Marine Crude Oil Transportation
Authors: Li Yi-Zhou , Hu Hao , Huang Dao-Zheng
Published: October 2012

As a scarce strategic resource, crude oil is closely intertwined with national strategies, global policies, international relationships, and national competence. Unbalanced demand and production of crude oil lead to huge amounts of import and export activities. Marine transportation accounts for about 80% of the total oil transport because of the low cost. However, it also incurs an extremely high risk in doing so. Therefore, it is significantly important to assess and control risk effectively in crude oil transportation. In risk assessment, uncertainty evaluation becomes a key variable that cannot be neglected. Previous cases show that fuzzy logic can be applied to manage uncertainty. However, the use of fuzzy logic usually encounters two difficulties: determination of the membership functions and establishment of the reference machine. This paper presents a dynamic fuzzy logic model (DFLM) that can improve the stated problems. The DFLM is developed from fuzzy theory and an incident causation model. The model is examined with a hypothetical case. Preliminary results show that the model reduces the time of risk assessment and increases the reliability of evaluation.
Maritime Transport Technology for the Other 90% of Us
Authors: Weisbrod Roberta
Published: October 2012

Maritime transport in the developing world is often unsafe and inefficient. The need for improvement is especially apparent in the record of fatal ferry incidents. A new approach to solving problems is Design for the Other 90% of Us, in which people in the developing and developed world collaborate to create products and systems that are robust, simple, and efficient. Using efforts to address ferry fatalities as a model, this paper investigates how the concept of Design for the Other 90% of Us could be applied to maritime systems in general. Recommendations for research and collaborative efforts are advanced.
Public Transportation Today and Tomorrow
Authors: Millar William W.
Published: October 2012

This paper synthesizes much of the information that describes the current state of public transportation in the United States and the benefits that result from investment in and use of public transportation. The paper begins with metrics describing the size of the transit industry and ridership trends over the past 70 years. Citing the economic importance of the nation's large urbanized areas, this paper focuses on the 30 largest transit systems measured by ridership, which serve 21 urbanized areas where 29% of the U.S. population lives and where 51% of the gross domestic product of the economy is produced. Data showing who uses public transportation and why are followed by a discussion of the four main drivers of transit use: convenience, necessity, economics, and philosophy. Some benefits that result from transit use are presented along with how they often accrue at essentially zero marginal cost when transit projects are well planned, well executed, and extensively used. The paper concludes with a look to the future: trends that favor transit expansion and use, technology improvements that are making transit more reliable and useful, and five lessons learned that must be followed for transit to be highly successful. The paper closes with a list of key public policy questions that, depending on how they are answered, may greatly influence the direction of public transportation.
Steps to Leading Change
Authors: Connolly Kevin , Wolfgram Laura , Santos Judis
Published: October 2012

Today's uncertain economic environment and changing demographics and land use patterns challenge transportation agencies to transform how they do business. Like some of its counterparts throughout the country, the Santa Clara Valley Transportation Authority (VTA) in Northern California has faced these challenges and is leading organizational change. This paper refines the process developed by John Kotter for successful organizational change in the private sector and applies the process to the public transportation industry. Examples from the development of VTA's Express bus business plan show how Kotter's private-sector organizational development concepts can be put into practice by a transportation agency. The paper also identifies the threats to change and opportunities for improvement based on lessons identified during interviews of external stakeholders and VTA staff. By presenting the approach used and the lessons learned, this paper can serve as a reference for transportation professionals whose strategic goal is to lead and implement change successfully within their agencies.
Developing Sustainable Methods of Distributing Federal Transit Funds
Authors: Sandidge Matt
Published: October 2012

FTA apportions Section 5307 urbanized area (UZA) formula funds to census-designated UZAs. When UZAs contain multiple recipients of Section 5307 funds, FTA leaves it up to local officials to determine the suballocations to the multiple recipients. Little documentation exists on the question of how to allocate the funds on a local level. The more agencies within a UZA, the more complex the issue becomes. Local officials within the UZAs must develop methods of allocating funds that satisfy the desires of each of the regional stakeholders. The nature in which metropolitan areas grow leads to multiple transit agencies existing within the UZA and desiring access to UZA formula funds. This report identifies seven complex metropolitan areas across the United States with multiple Section 5307 fund recipients, identifies the problems experienced with allocating Section 5307 funds at the local level, and identifies three models of funding distribution techniques. The models of funding distribution include formula, formula and regional project selection, and regional project selection and local negotiations. Though only three models are identified, there is much variation within each model. The report provides details on the allocation within each region.
Strategic Look at Friday Exceptions in Weekday Schedules for Urban Transit
Authors: Lu Alex , Reddy Alla
Published: October 2012

This paper describes a strategic business case for weekday exception scheduling in urban transit services, specifically, treating Fridays differently from other weekdays. As commuters trend toward more flexible work scheduling, telecommuting arrangements, and 4½-day weeks, gaps between midweek and Friday ridership volumes have widened. Exception schedules neither were nor are unusual; transit operators ran full Saturday lunchtime peak-hour service in the interwar era, while private bus companies, airlines, and freight railroads operate exceptions today. Systematic consideration of day-of-week scheduling confirmed that Friday modifications were best leveraged in better matching of service supply to ridership demand. Longitudinal analysis of New York City Transit automated fare collection data revealed that more regular commuters skipped a Friday trip than other weekday trips. Analysis by route and time period for 14 representative routes over 10 months showed 4.7% lower ridership levels on Fridays, potentially allowing 7.4% reductions in vehicle hours operated. Available savings were route specific, with 25% service reductions possible on some routes, but service increases of 25% were required on other routes with higher Friday ridership. Implementing separate Friday schedules systemwide could provide a surplus of $10 to $17 million (0.6%) for reinvestment elsewhere in the network. Additionally, reduced Friday crew requirements could lead to increases of 1.2% to 2.4% in desirable weekend-inclusive regular days off (RDOs) and a 2.4% reduction in nonpreferred midweek RDOs. Two prerequisites for realizing savings are a computerized run-cutting system and an infrastructure for ridership analysis across multiple days, routes, and time periods. Transit agencies should determine whether routes can benefit from weekday exceptions. If productivity improvements are indicated, contracts permitting weekday work program exceptions can be negotiated.
Analyzing Passenger Incidence Behavior in Heterogeneous Transit Services Using Smartcard Data and Schedule-Based Assignment
Authors: Frumin Michael , Zhao Jinhua
Published: October 2012

Passenger incidence (station arrival) behavior has been studied primarily to understand how changes to a transit service will affect passenger waiting times. The impact of one intervention (e.g., increasing frequency) could be overestimated when compared with another (e.g., improving reliability), depending on the assumption of incidence behavior. Understanding passenger incidence allows management decisions to be based on realistic behavioral assumptions. Earlier studies on passenger incidence chose their data samples from stations with a single service pattern such that the linking of passengers to services was straightforward. This choice of data samples simplifies the analysis but heavily limits the stations that can be studied. In any moderately complex network, many stations may have more than one service pattern. This limitation prevents the method from being systematically applied to the whole network and constrains its use in practice. This paper considers incidence behavior in stations with heterogeneous services and proposes a method for estimating incidence headway and waiting time by integrating disaggregate smartcard data with published timetables using schedule-based assignment. This method is applied to stations in the entire London Overground to demonstrate its practicality; incidence behavior varies across the network and across times of day and reflects headways and reliability. Incidence is much less timetable-dependent on the North London Line than on the other lines because of shorter headways and poorer reliability. Where incidence is timetable-dependent, passengers reduce their mean scheduled waiting time by more than 3 min compared with random incidence.
Extraboard Performance
Authors: Strathman James G. , Kwon Sung Moon , Callas Steve
Published: October 2012

This paper examines extraboard operations at TriMet, the transit provider for the Portland, Oregon, metropolitan area. The extraboard consists of a pool of operators who fill open work resulting from absences and other causes. Drawing on 7 years of daily operations data, the paper examines first the general performance of the extraboard in filling open work. The paper then presents statistical analyses focusing on open work patterns and the effects of selected work rules on operator utilization and service delivery. Last, suggestions are made for improving the efficiency of extraboard operations.
Simulating the Travel Time Impact of Missed Transit Connections
Authors: Mai Eric , List George , Hranac Rob
Published: October 2012

It is well established that transit passengers dislike transferring, in part because of the inherent risk that the connecting vehicle will be missed, a risk that can increase overall travel time. Despite the problems that missed transfers cause, such transfers across a system are rarely tracked in transit performance monitoring programs. The likelihood of a missed transfer depends on combinations of several factors and thus is hard to estimate. In practice, transit systems are most often evaluated according to the performance of individual vehicles, stops, and routes, not the interactions between them. This paper describes a systems approach to quantify the effects of travel time reliability, schedule adherence, and schedule design on missed transit connections, and the resulting travel time distributions. To determine the effects of vehicle interactions on transfers and the role that transfers play in travel time, a series of simulations based on automatic passenger counting data from the bus system in San Diego, California, was performed. Travel times on two transfer trips in downtown San Diego were simulated. The effects of passenger arrival rate, on-time vehicle performance, and schedule design on the likelihood of a transfer being missed were investigated in a sensitivity analysis. This research is expected to lead to a better understanding of the passenger effects of schedule adherence on transfer trips. Practically speaking, this methodology could aid in the identification of pairs of buses whose chronic schedule deviations at a particular location are likely causing missed transfers.
Marginal Cost Pricing and Subsidy of Small Urban Transit
Authors: Mattson Jeremy , Ripplinger David
Published: October 2012

This study analyzes economies of scale and density as a rationale for subsidizing transit agencies in small urban areas. A long-run cost model is estimated with data from 2006 to 2009 for 168 transit agencies that directly operated fixed-route bus service in small urban areas. With vehicle revenue miles used as transit output, results show that small urban transit agencies experience economies of scale and density. A full-cost model is estimated; the model includes the addition of external costs and benefits. External benefits result from the reduced waiting times that follow an increase in service frequency. Results are used to estimate the optimal fare, which is equal to marginal social cost of service. The needed subsidy is calculated as the difference between the revenue generated by the optimal fare and that needed to maintain efficient levels of production. The rationale for subsidies is an important issue, as many agencies have experienced recent reductions in operational funding.
Effects of Tube Strikes on Journey Times in Transport Network of London
Authors: Tsapakis Ioannis , Turner Jonathan , Cheng Tao , Heydecker Benjamin G. , Emmonds Andy , Bolbol Adel
Published: October 2012

The goal of this study was to investigate the impact of five underground strikes on journey times in London's transport network during 2009 and 2010. The main data source for this study was automatic number plate recognition cameras, which were installed on the entrances and exits of 670 travel links that covered the vast majority of the network and were equivalent to a total length of 1,740 km. The determination of spatio-temporal differences of strike effects between the first and the remaining strike days, the identification of changes in departure and arrival times, and the estimation of travel time delays within central, inner, and outer London, as well as between inbound and outbound traffic, were the main objectives of the study. The total travel time within the examined areas, the excess delay, and the corresponding percentage difference in journey times were the main performance measurements used. The most significant results showed that the second day of strikes resulted in significant delays as opposed to the first strike days. The peaks elongated by approximately 45 to 60 min, while the unique full-day strike had the highest percentage increase in travel times, especially during the evening period (74%). Central London was generally affected the most, especially during the morning peak, which experienced an average increase in travel times of 35%, while Central London also had the highest percentage of negatively affected links (80%). The inbound traffic experienced, on average, high delays during the morning peak; the outbound traffic yielded greater delays during the evening period.