bluuebunny/crossref_metadata_2025 huggingface dataset:
Methods for Evaluating Longitudinal Joint Quality in Asphalt Pavements
Authors: Williams Stacy G. , Pervis Ashly , Bhupathiraju Leela Soujanya , Porter Annette
Published: September 2009

Longitudinal joint quality is essential to the successful performance of hot-mix asphalt (HMA) pavements. Longitudinal joints have received a considerable amount of attention recently, because many state agencies are moving toward implementation of longitudinal joint specifications. Most measures of joint quality are based on density determinations. However, distress at the joint is caused by the ability of air and water to enter the pavement structure, an action that is directly related to the permeability of the joint. In other words, density alone may not be sufficient to describe the quality of a longitudinal joint. The objective of this study was to identify the most appropriate test method or methods for describing HMA longitudinal joint quality. Three projects were selected for the study, and four testing stations were identified for each project. At each station, a number of test methods were performed at the longitudinal joint and to either side of the joint to assess the ability of each method to properly discriminate between levels of joint quality. Multiple measures of density, permeability, and gradation were obtained at each station. Overall, the methods providing the most accurate predictions of joint quality and the greatest level of discrimination were the vacuum sealing and saturated surface-dry (SSD) methods for determining the bulk specific gravity of field cores. Although measures of permeability and infiltration showed promise, it was recommended that the vacuum sealing and SSD methods for the determination of field core density be considered in the evaluation of longitudinal joint quality.
Strategies for Design and Construction of High-Reflectance Asphalt Pavements
Authors: Tran Nam , Powell Buzz , Marks Howard , West Randy , Kvasnak Andrea
Published: September 2009

The occurrence of higher air and surface temperatures in urban areas is known as the urban heat island (UHI) effect. Reducing the UHI effect may decrease summer energy use and improve human and ecological health. The Leadership in Energy and Environmental Design certification system has awarded up to three points for construction projects that provide any combination of the following cool pavement strategies for up to 75% of the site landscape: ( a) shading hard surfaces on the site with landscape features, ( b) using high-reflectance materials with a minimum solar reflectance index (SRI) of 29, and ( c) utilizing an open-graded pavement or porous pavement system. Although a guide to the design and construction of porous asphalt pavements has existed for some time, such a guide is not readily available for high-reflective asphalt pavements. The objective of this study is to identify and validate high-reflectance asphalt materials and pavement surface treatments that are suitable for use in parking lots and other large paved surfaces, have a minimum SRI of 29, and are economical. In this study, six technologies exhibited SRI values of 29 or greater: E-Krete microsurfacing, Street-Bond coating, synthetic binder, Densiphalt, and chip and sand seals using light-colored aggregates. Another technology, surface gritting using light-colored aggregate, most likely would have exhibited SRI values of at least 29 if the aggregate had adhered properly to the asphalt mat.
Use of Stay-in-Place Forms for Concrete Bridge Decks in Tennessee
Authors: Knight Marcus L.
Published: September 2009

Bridge decks, concrete or otherwise, represent one of the most heavily deteriorated components of typical highway bridges. Bridge construction continues to proceed at high volume, and in the past, bridge repair, rehabilitation, and replacement increased as well. Enormous amounts of funding are required to support initial construction and repairs as needed. This national trend is also evident within the Tennessee bridge inventory, which currently numbers approximately 20,000, with a majority of the structures utilizing concrete cast-in-place decks. Because of the increasing volume of work and limited funding, efficient methods of constructing and repairing concrete bridge decks have been of interest during the past decades. Durable, high-quality bridge decks have been constructed in Tennessee with three primary forming systems: temporary forms and falsework and stay-in-place form systems consisting of precast concrete panels and permanent steel forms. Each of these form systems is discussed, with a description of typical applications and estimation of the frequency of use. Currently, cast-in-place decks in Tennessee represent approximately 60% of the inventory and are predominantly (90%) cast by using permanent steel forms. The effects of stay-in-place forms on finished cast-in-place decks were investigated as well as form durability and inspection and repair considerations. This information was obtained through review of Tennessee Department of Transportation specifications and standard drawings and interviews of department personnel.
Impact of Dynamic Message Signs on Satisfaction and Diversion of Toll Road Travelers
Authors: Al-Deek Haitham , Chilakamarri Venkata Srinivasa Ravi Chandra , Flick Jason
Published: September 2009

Dynamic message signs (DMS) are electronic signs used on roadways to give travelers information about travel times, congestion, incidents, and other alerts. The reaction that travelers have to such sources depends on their perception of the utility of these sources. The effects of DMS on driver behavior and driver expectations of information for nontolled roads are well documented. The purpose of this research was to evaluate the impact of DMS on toll road users in Orlando, Florida, by using a predeployment (one DMS operational) and postdeployment (29 DMS operational) survey analysis. A detailed telephone survey was administered, and modeling was performed to estimate the effects of DMS deployment on attitudes and behavior of toll road travelers. The satisfaction of travelers with certain DMS aspects and their diversion response to information on DMS were compared between the pre- and postdeployment survey periods. The results for satisfaction models showed that in predeployment, travelers valued accuracy and hazard warnings highly toward overall satisfaction. In postdeployment, travelers highly valued special event information, hazard warnings, and accuracy. The postdeployment diversion behavior model showed that increased travel time savings, 511 service, and cash mode of toll payment encouraged diversion. Travelers who experienced abnormal travel times on DMS or who reported that DMS helped them during congestion were more likely to divert. Further, this study showed that toll road users might have a greater inertia and avoid leaving the toll road when compared with non–toll road users. Implications of the results are discussed.
Flow Breakdown at Freeway Bottlenecks
Authors: Banks James H.
Published: September 2009

An automated analysis of cumulative flow and speed curves was used to investigate issues related to flow breakdown at freeway bottlenecks, including ( a) the relationship between prebreakdown flow rates and the amount of time they can be sustained, ( b) flow trends in the period immediately before breakdown, and ( c) the probability that flow decreases at breakdown. The automated analysis allowed consistent application of explicit rules to identify bottleneck activation and deactivation, periods of nearly constant flow, and so on. Data analyzed did not provide evidence of a strong relationship between the flow rate and the amount of time that nearly constant prebreakdown flow can be sustained, although a weak relationship may be present. Periods of nearly constant flow occurred before initial flow breakdown about half the time; the average duration of these periods was roughly 30 min. Periods of both increasing and decreasing flow were also observed. Flow decreased at breakdown roughly two-thirds of the time. The lack of a strong relationship between the flow rate and time to breakdown suggests that ramp metering is unlikely to be effective in prolonging high-volume prebreakdown flow. Metering is more likely to be effective if it is used to eliminate or control very specific causes of flow breakdown, such as arrival of dense platoons of ramp vehicles at the merge point or high concentrations of traffic in the right lane immediately downstream from a ramp.
Marginal Incident Computation
Authors: Corthout Ruben , Tampère Chris M. J. , Immers Lambertus H.
Published: September 2009

In studies on the influence of incidents on travel time, researchers rely on Monte Carlo simulation. Because this procedure is demanding computationally, the research scope is limited. This paper presents a highly efficient method for approximately quantifying congestion spillback due to incidents: marginal incident computation (MIC). MIC superimposes the effect of an incident on a single base simulation run (without incidents) instead of carrying out a complete dynamic network loading with the incident, which would involve many calculations identical to the base simulation (e.g., before or far away from the incident). Whereas the results obtained with MIC vary only slightly from the outcome of a complete dynamic network loading, the gain in computation time is significant: a factor > 1,100 for a case study of the Sioux Falls, South Dakota, benchmark network.
Experiment to Improve Estimation of Vehicle Queue Length at Metered On-Ramps
Authors: Wu Jingcheng , Jin Xia , Horowitz Alan J. , Gong Daqing
Published: September 2009

Two types of algorithms for on-ramp queue estimation are discussed; a Kalman filter and a conservation model. A volume-balancing ratio is introduced to both models to account for unavoidable detector miscounting behavior. Estimation results are compared with queue data observed in the field. The volume-balancing ratio improves both models. Although the conservation model may provide more accurate prediction with balanced volumes, the Kalman filter tends to provide better estimation when the volume-balancing ratio deviates from 1. Generally the Kalman filter provides a better prediction, but the conservation model is simpler to implement. Attempts to improve the Kalman filter further are also explored.
Are Incident Durations and Secondary Incidents Interdependent?
Authors: Khattak Asad , Wang Xin , Zhang Hongbing
Published: September 2009

Incidents impose substantial social and personal costs on drivers. Some of the larger incidents that cause delays are also associated with secondary incidents. However, the nature of interdependence between primary and secondary incidents is not fully known. The objective of this study is to understand how primary incident duration and secondary incident occurrence are related. Specifically, secondary incidents are more likely to occur if the primary incident lasts a long time; at the same time, the durations of primary incidents are expected to be longer if secondary incidents occur. After traffic incident and road inventory data in the Hampton Roads, Virginia, area were obtained, secondary incidents were then identified. Secondary incidents were defined as incidents occurring on the same roadway segment (which average 1 mi in length) as the primary incident and within the actual duration of the primary incident. If the primary incident blocked lanes, then the actual duration plus 15 min was used as the threshold. Models for primary incident durations and whether a secondary incident occurs are estimated. The interdependence is modeled by considering incident duration as endogenous in the secondary incident occurrence models. Results show statistical evidence for interdependence, but when it is taken into account, no substantial differences in the magnitudes and statistical significance for the estimated independent variables are found (compared with when the interdependence is not accounted for). Statistically significant correlations found between secondary incident occurrence and other variables allow the recommendation of specific operational strategies.
Loop Detector Segmentation Error and Its Impacts on Traffic Speed Estimation
Authors: Yu Runze , Zhang Guohui , Wang Yinhai
Published: September 2009

Most traffic sensors currently deployed along the existing freeway systems are single-loop detectors that directly measure only volume and lane occupancy. Because loop detector actuations (event data) consume extra resources to store and transfer, transportation agencies typically aggregate loop detector measurements into 20- or 30-s intervals in field traffic controllers before sending them to the Traffic System Control Center for archiving. Therefore, only aggregated volume and lane occupancy data for each aggregated interval are available for use. During the aggregation process, however, a vehicle may be present on a loop when the current aggregation interval terminates. In that case the vehicle is counted toward the following interval, but part of its scan counts is mistakenly assigned to the current interval. The incorrect number of scan counts can cause occupancy measurement errors, referred to as segmentation error (SE) in this study. This error occurs frequently and adversely affects the quality of loop data, especially when volume is low. Because single loops rely on certain algorithms for speed estimation using the aggregated measurements, SEs can result in biased speed estimates. This paper studies the impact of SE on speed estimates and proposes an improved speed estimation algorithm that is easy to implement and effective in eliminating SEs. Compared with Athol's speed estimation algorithm, widely used in practice, the new algorithm produces improved speed estimates. A thorough analysis of the frequency of SE and the level of negative impacts on speed estimation is also conducted.
Imputation of Ramp Flow Data for Freeway Traffic Simulation
Authors: Muralidharan Ajith , Horowitz Roberto
Published: September 2009

The Tools for Operational Planning is a suite of tools that uses the link–node cell transmission model for macroscopic freeway traffic simulations for specifying operational strategies such as ramp metering and demand and incident management. Traffic flow and occupancy data from loop detectors are used for calibrating these models and specifying the inputs to the simulation. Flow data from ramps, however, are often found to be missing or incorrect. This paper elaborates an imputation procedure used to determine these ramp flows. This automated imputation procedure is based on an adaptive identification technique that attempts to minimize the error between the simulated and the measured densities. Simulation results using the imputed flow data indicate good conformation with loop detector measurements.
Automatic Freeway Incident Detection Based on Fundamental Diagrams of Traffic Flow
Authors: Jin Jing , Ran Bin
Published: September 2009

Algorithms for automatic incident detection (AID) detect traffic incidents on the basis of traffic flow measurements. There are two important steps in an AID algorithm: traffic flow feature generation and incident decision making. In the past decade, the research on freeway AID algorithms has been focused on using artificial intelligence to optimize the decision making of AID algorithms. In this paper, the primary focus is on finding a new set of variables for the feature generation. The new variables, uncongested and congested regime shifts (URS and CRS), are generated by conducting coordinate transformation on loop-detected flow and occupancy measurements. A novel AID algorithm, the fundamental diagrams–based automatic incident detection (FD AID) algorithm, is then developed by implementing the incident-related traffic flow knowledge using those variables. Preliminary results show superior performance of the FD algorithm compared with legacy algorithms.
Managing Congestion in Large Brazilian Urban Area through Logical Interface between SCOOT and GIS Platform
Authors: Loureiro Carlos Felipe G. , Meneses Hamifrancy Brito , de Oliveira Neto Francisco Moraes , de Castro-Neto Manoel Mendonca
Published: September 2009

Effective management of traffic congestion is based on a continuous, systematic understanding of travel behavior in the urban network. A continuous effort of data collection, treatment, and analysis is demanded and requires time, financial resources, and skilled staff. An efficient alternative for urban traffic management consists of implementing traffic management centers (TMCs), which collect, model, and store data relating to traffic conditions. However, the operational systems usually implemented in those centers do not offer effective mechanisms for consulting their databases because they are designed with an emphasis on traffic signal control. This work presents the development of a logical interface between the dynamic database of the TMC of Fortaleza, Brazil (CTAFOR), and the TransCAD geographic information system (GIS) platform. This interface combines an open modular architecture and a spatiotemporal model to import dynamic traffic data into the static GIS platform. The interface also provides flexible, efficient access to the data collected in real time by CTAFOR's adaptive traffic control system, SCOOT, and gives the data a spatial attribute in TransCAD software. With the interface available, the second main objective was to implement performance measures to evaluate the efficiency and effectiveness of the operational actions taken in the area controlled by CTAFOR and assess how well the objectives set to the TMC are being achieved. After the development of the TRANSCOOT interface, the ITS data collected and simulated at CTAFOR have been used to support real-time operations and to allow tactical, strategic decision analyses, based on performance measures aggregated by their spatial and temporal attributes.
Traffic Management of Special Events in Small Communities
Authors: Lassacher Suzanne , Veneziano David , Albert Steve , Ye Zhirui
Published: September 2009

Planned special events (PSE), such as sporting events and concerts, produce nonrecurring congestion as attendees simultaneously attempt to exit the event and overload the local transportation network. These types of events can have a significant impact on traffic operations, particularly in small urban and rural environments, where limited infrastructure is available to access and egress the PSE venue. The research presented here applied a variety of traffic management strategies to manage congestion resulting from football games at Montana State University in Bozeman, Montana, in fall 2007. These strategies included the provision of real-time travel information, road closures, traffic signal retiming, and real-time traffic monitoring. Results indicated that these strategies could be successfully applied in a rural community to manage the congestion arising from PSEs. For example, results indicated that signal retiming and manual traffic control strategies allowed for improvements in traffic flow on approaches that served game traffic.
Analysis of Standard Operating Procedures for Enhanced Regional Transportation Systems Operations
Authors: Smith Brian L. , Venkatanarayana Ramkumar , Griffin Stephen O.
Published: September 2009

Traditionally, transportation system operations have been constrained by jurisdictional and administrative boundaries. Local governments and state agencies have operated facilities for which they are responsible with little coordination. As surface transportation mobility challenges continue to increase, it is evident that although different localities and agencies may still operate their own systems, there is a need for coordinated regional operations. An important component of enabling such coordination is the achievement of consistency in the standard operating procedures (SOPs) used by the individual transportation operations centers (TOCs). Historically, each TOC has developed its own SOPs, suited to its own unique needs and the resources available. Although these individual SOPs have served their TOCs well, such customized operations procedures of a TOC are often not compatible with its neighboring TOCs. As such, establishing regional coordination, especially to manage large-scale incidents or emergencies, is difficult. In this research effort a methodology was developed to analyze TOC SOPs to find opportunities to increase regional consistency. This methodology was applied in a case study to analyze the SOPs of the five TOCs and the statewide emergency operations center in the state of Virginia. The results of this study indicate that several differences indeed hamper coordination among the centers. At the same time a number of procedures with the potential for increased consistency are also identified. Information contained in this paper will benefit systems integrators, planners, researchers, and other transportation professionals involved in regional integration efforts and in policy and procedures review.
Prototype for Data Fusion Using Stationary and Mobile Data
Authors: Berkow Mathew , Monsere Christopher M. , Koonce Peter , Bertini Robert L. , Wolfe Michael
Published: September 2009

Arterial performance measurement is a critical issue for transportation system management, traveler information, and real-time situation-aware routing. In many urban areas current information on freeway conditions is available, appropriately given the large amount of travel that occurs on these facilities. However, because nearly 40% of the vehicle miles traveled in the United States occur on arterials, there is a need to provide similar information that can be used not only by travelers but also by traffic engineers and managers. Because many arterials are equipped with actuated traffic signals, the use of already installed sensors has been explored as one source of traffic volume, occupancy, or speed data to inform an arterial performance system. Coupled with this, there is a potential to exploit the availability of mobile probe geolocation data from sources such as automatic vehicle location systems for fleets of buses or taxis, or from cellular phone or other Global Positioning System–type devices. To demonstrate the potential value of fusing data from fixed and mobile surveillance systems toward improved arterial performance reporting, this paper describes the results of a case study from Portland, Oregon, that extracted improved arterial performance measures by combining data from traffic signal system detectors and from buses acting as probe vehicles. In particular, graphical techniques are developed that trace the boundaries of the congested regime in time and space along an arterial corridor. The paper includes recommendations for expanding the techniques to other corridors, using higher resolution, real-time transit location data, and online implementation of an arterial travel time information system.
Investigating the Impact of Tolls on High-Occupancy-Vehicle Lanes Using Managed Lanes
Authors: Burris Mark W. , Ungemah David H. , Mahlawat Maneesh , Pannu Mandeep Singh
Published: September 2009

For nearly 40 years, high-occupancy-vehicle (HOV) lanes have been used to combat congestion. These lanes allow only vehicles with multiple occupants and generally offer a free-flow trip, unlike adjacent general purpose lanes. In theory, this encourages additional carpooling, reduces overall vehicle miles of travel, and improves the commute trip. However, as a result of the underutilization of some of these lanes, some HOV lanes are migrating to high-occupancy-toll (HOT) lanes, where HOVs may travel free of charge but lower-occupancy vehicles can pay a toll to use the lane. This research investigated the impacts of offering preferential treatment for HOVs on these lanes. To determine the impact of different HOT lane operating strategies on their travel behavior, freeway travelers in the Houston and Dallas metropolitan areas of Texas were surveyed. A nested logit model was developed to estimate the mode choice for travelers. This model was used to predict the impact of converting an HOV lane to a HOT lane on which all travelers pay a toll. It was found that the overall percentage of HOV2 and HOV3+ vehicles in the traffic stream decreased by only a small amount when a toll was required for them to use the HOV lane. However, that decrease did represent a significant portion of those modes (more than 9%) and resulted in more than a 10% increase in HOT lane revenue. Therefore, elimination of preferential treatment for these vehicle types has significant implications and becomes a difficult policy decision—not just a straightforward choice.
Safety Evaluation of Truck Lane Restriction Strategies Using Microsimulation Modeling
Authors: El-Tantawy Samah , Djavadian Shadi , Roorda Matthew J. , Abdulhai Baher
Published: September 2009

The demand for goods and services in North America has increased dramatically over the past few decades. This demand increase resulted in an associated increase in truck traffic on North American highways, escalating congestion, operation, and safety concerns. This in turn has led to increasing interest in strategies to reduce interaction between trucks and cars, including truck restrictions and dedicated truck lanes. The purpose of this paper is to implement algorithms for evaluating safety measures for different scenarios of truck lane restrictions and dedicated truck lanes using microscopic traffic simulation. The measures of performance calculated in this study are lane changing, merging, and rear-end conflicts. These measures are analyzed for truck-restricted lanes and dedicated truck lanes on the Gardiner Expressway in downtown Toronto, Canada. Simulation scenarios are developed by varying lane strategies and truck percentage. Simulation results showed that implementation of a single truck-restricted lane makes little difference to most conflict measures. Restricting trucks from the leftmost two lanes results in more substantial reductions in lane changing conflicts, but causes some increased freeway merging conflicts involving trucks. Dedicating the leftmost lane only to trucks also reduces lane changing conflicts but increases lane merging conflicts. Because lane changing conflicts are far more frequent than merging conflicts, there appears to be a net safety benefit by either restricting trucks from the left two lanes or dedicating the left lane to trucks. Relationships between lane strategy and rear-end conflicts are weak. Truck lane strategies are most effective when truck percentage exceeds 15%.
Safety Performance of High-Occupancy-Vehicle Facilities
Authors: Jang Kitae , Chung Koohong , Ragland David R. , Chan Ching-Yao
Published: September 2009

Collision data from high-occupancy-vehicle (HOV) facilities with two different types of access, continuous and limited, are examined in this paper. The findings show that HOV facilities with limited access offer no safety advantages over those with continuous access. Compared with continuous access HOV lanes, a higher percentage of collisions were concentrated on limited-access HOV lanes. Limited-access HOV lanes also had higher collision rates. Findings from investigating the relationship between collision rates in HOV lanes with respect to shoulder width, length of access, and proximity of access to neighboring ramps are also documented. These findings provide enhanced understanding about the effects of geometric factors on the collision rates in HOV lanes.
An Approach to Assessing Freeway Lane Management Hot Spots
Authors: Chung Chih-Lin , Recker Wilfred W.
Published: September 2009

This research presents a procedure for capitalizing on the trade-off between urban freeway managed lanes and general purpose lanes that compete for limited road space. The basic goal of the procedure is to provide policy guidance for sharing any excess lane capacity on a timely and efficient basis. Potential operating policy options for these two types of lanes are categorized as “do nothing,” “lane management,” and “more than lane management.” The “lane management” condition recognizes the extent and duration of a “hot spot” as defined by underutilized managed lanes with congested general purpose lanes, or vice versa. Four major and three minor lane management hot spots are deterministically and stochastically captured along a 24-mi freeway stretch in California. The major hot spots account for 8.3% of the total time–space set. The approach, which can also be applied to predict upcoming hot spots, generates satisfying accuracy. Finally, strategies are proposed to prevent the hot spots, and the effects of lane management are estimated. The application of this approach is useful especially for managed lanes with limited access points that prohibit arbitrary lane changing.
Local Seaport Initiatives Driving International Policy
Authors: Knatz Geraldine
Published: September 2009

This paper discusses the evolution of U.S. seaports and the environmental initiatives enabling them to modernize and expand. These initiatives, such as the Port of Los Angeles Clean Air Action Plan, will likely be seen as watershed moments for transformational changes in the port and maritime industries. Seaport-related environmental and public health issues are addressed; solutions posed by local, federal, and international organizations are discussed and analyzed; and innovations in emissions-reducing technologies for both oceangoing vessels and the cargo-handling equipment employed by seaports and the areas surrounding these ports are explored.
Planning for Impacts of Climate Change at U.S. Ports
Authors: Gallivan Frank , Bailey Kathleen , O'Rourke Larry
Published: September 2009

U.S. ports need to better understand climate change and how it may affect them. In the coming decades, ports are likely to experience higher sea levels and storm surges, as well as other direct and indirect impacts, due to climate change. Most ports do not appear to be thinking about, let alone actively preparing to address, the effects of climate change. Ports do not have specific information about either the types of impacts that they can expect on their facilities or the probabilities of different types of impacts occurring. Although climate change science is making considerable advances, projections of impacts at levels smaller than the regional scale are not available. In addition, ports’ typical planning processes are ill equipped to respond to the high levels of uncertainty associated with the impacts of climate change, the timescales of climate change, and the geographical scale of climate change. The data that ports typically use for planning purposes do not incorporate climate change forecasts. Some ports also believe that climate change does not pose an immediate threat to their facilities. However, several ports are beginning to think about how to prepare for climate change. These include the Port of Miami (Miami, Florida), the Port Authority of New York and New Jersey, the Massachusetts Port Authority, the Port of Seattle (Seattle, Washington), the Port of Corpus Christi (Corpus Christi, Texas), and the Georgia Ports Authority. To help these and other ports assess their risk, more and better data are needed, as well as better planning tools and methods.
Container Terminal Berth Planning
Authors: Theofanis S. , Boile M. , Golias M. M.
Published: September 2009

A comparative, up-to-date, critical review of existing research efforts relating to berth planning is presented. Existing models are critically reviewed on the basis of their efficiency in addressing key operational and tactical questions relating to vessel service and their relevance and applicability to different marine terminal operator berth-planning strategies and contractual service arrangements between terminal operators and ocean carriers. The strengths and deficiencies of the existing models in addressing real-world problems in a systemic and coherent manner are discussed. The paper concludes with some insights for future research issues.
Application of Lean Enterprise to Improve Seaport Operations
Authors: Loyd Nicholas , Jennings Lauren C. , Siniard Jeff , Spayd Michael L. , Holden Anthony , Rittenhouse George
Published: September 2009

This paper discusses the implementation of Lean Enterprise management, principles, and tools in seaport operations. The paper begins with an overview of the necessary management training, strategy, and structure necessary for the successful implementation of Lean Enterprise. An analysis of the appropriate Lean Enterprise tools to be applied in seaport operations is provided, and specific examples of the implementation of those tools at the Port of Mobile in Mobile, Alabama, are cited. The paper also investigates the importance of integrating Lean Enterprise concepts into support functions such as accounting, maintenance, and human resources to enhance overall port operations in a holistic manner. The paper concludes with a discussion of the keys to the successful implementation of Lean Enterprise and the issues relative to sustaining improvement efforts as well as suggestions for additional focuses of improvement for implementing Lean Enterprise in port operations.
Performance Indicators for Roll-on–Roll-off Terminals
Authors: Morales-Fusco Pau , Saurí Sergi
Published: September 2009

Road freight transportation has increased dramatically over recent years, as have accompanying impacts such as congestion, noise, and pollution. As a result, European governments and the U.S. government started implementing policies to promote alternatives to road transportation, such as logistic chains containing a short sea shipping (SSS) link. Shipping by road is a more flexible means of transportation than shipping by sea, which is usually cheaper. Therefore, to move traffic to SSS chains, it is necessary to provide fast, frequent, and reliable maritime transportation. In this sense, roll-on–roll-off (RoRo) vessels are the most convenient types of vehicles to be used because they have shorter dwell times in port. Therefore, the level of this kind of traffic is likely to increase dramatically. To cope with the increase in traffic, terminal managers must decide whether a change in the terminal's operation would suffice or whether the enlargement or construction of a new terminal, given the level of service provided, is necessary. This paper proposes a methodology that can be used to relate the level of service in a RoRo terminal to its capacity from the ship's point of view. This goal is achieved by using several quality indicators that, in turn, should allow terminal managers to foresee what the level of service that they offer to shipping companies would be, given the numbers of arrivals and their distribution, as well as the terminal's performance. The paper ends by applying the methodology to a real terminal in Barcelona, Spain.
Reducing Truck Turn Times at Marine Terminals with Appointment Scheduling
Authors: Huynh Nathan
Published: September 2009

This paper addresses a critical component of truck appointment systems: scheduling rules. The goal of this study is to gain an understanding of how the various scheduling rules affect resource utilization and truck turn time in grounded operations. Such an understanding could influence terminal operators and appointment service providers to make changes to their current scheduling practice. To this end, this study seeks to develop a framework for the evaluation of ( a) the performance of various simple appointment-scheduling rules under a variety of operating scenarios and ( b) the major factors affecting the performance of scheduling rules. This study considers two types of appointment-scheduling strategies that were adopted from the health care sector: ( a) individual appointment systems (IASs) and ( b) block appointment systems. To determine the effectiveness of the scheduling strategy, this study relies on a simulation model of a container terminal. Simulation is used because it provides a more realistic representation of the complex operations at terminals. In addition, it circumvents the restrictive assumptions of analytical methods. The simulation model developed was constructed with the Flexsim CT discrete event simulation software, the first commercially available off-the-shelf simulation tool for container terminals. The experimental results show a clear benefit for a terminal without an appointment system to use the IAS. Such a scheduling system keeps the yard cranes highly utilized, and it improves the internal yard turn time by about 44%. With the proper spacing between appointments, the IAS can be effective even when a good portion of trucks are walk-ins, no-shows, or late (up to 1 h).
Modeling Gate Congestion of Marine Container Terminals, Truck Waiting Cost, and Optimization
Authors: Guan Chang Qian , Liu Rongfang (Rachel)
Published: September 2009

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.
Hierarchical Modeling of Perceived Collision Risks in Port Fairways
Authors: Debnath Ashim Kumar , Chin Hoong Chor
Published: September 2009

Navigational collisions are one of the major safety concerns in many seaports. Despite the extent of work recently done on port navigational safety, little is known about harbor pilots’ perception of collision risks in port fairways. The study described in this paper used a hierarchical ordered probit model to investigate the associations between perceived risks and the geometric and traffic characteristics of fairways and pilot attributes. Perceived risk data, collected through a risk perception survey of Singapore port pilots, were used to calibrate the model. The intraclass correlation coefficient justified the use of the hierarchical model rather than an ordinary model. The results show higher perceived levels of risk in fairways attached to anchorages and in those featuring sharper bends and higher traffic operating speeds. Lower levels of risk were perceived in fairways attached to the shoreline and confined waters and in those with one-way traffic, a traffic separation scheme, cardinal marks, and isolated danger marks. The level of risk was also found to be perceived higher at night.
Operational Development of Marine Highways to Serve the U.S. Pacific Coast
Authors: Bagnell Dan , Saunders Carin , Silva Ron , Tedesco Matthew P.
Published: September 2009

This paper examines the market volumes, service times, vessel characteristics, and economics for marine highways that would serve the U.S. Pacific Coast. This work was performed under contract to the Center for Commercial Deployment of Transportation Technologies. Market volumes were assessed by routes of interest and by filtering for cargo that would be eligible for marine highway service on the basis of the drayage distance and other factors. Sufficient daily truckload volumes exist in the Northern California to Southern California route to justify marine highways with multiple daily sailings of vessels with capacities of 450 to 700 trailers, should service times and economics prove to be competitive enough to divert cargo. Market volumes in the California to Pacific Northwest route are sufficient for daily sailings of smaller vessels with capacities of approximately 150 to 200 trailers. A door-to-door supply chain perspective was maintained, and discrete-event simulation was used to assess the service times and the vessel speeds required. The resulting voyage analysis served as input to both a parametric analysis of vessel characteristics and an economic analysis of marine highways by considering all maritime and land-side cost elements associated with the door-to-door movement of trailers. It was concluded that current truck rates are not high enough for marine highways to compete on the basis of cost in short next-day-turnaround markets, such as Northern California to Southern California. Marine highways are viable for longer routes such as those from California to the Pacific Northwest, where truck rates are higher and both distance and trucking hours-of-service regulations permit vessels to be time competitive at lower speeds.
An Integrated Set of Indicators for Assessment of Inland Waterway Transportation Performance
Authors: Posset Martin , Pfliegl Reinhard , Zich Andreas
Published: September 2009

Ever-growing supply chains and the corresponding demand for efficiency and reliability necessitate improved performance and measurement standards. Enhanced competitiveness is the unifying element within every industry and drives improved performance and a demand for high-quality services. New methods and tools for measurement of the performance of inland waterway navigation are therefore needed. The real challenge is to develop internationally applicable performance indicators (PIs) to ensure correct decision making and improved competitiveness. Therefore, it is essential to consider the related processes, the stakeholders being addressed, and the scope of the underlying system. The purpose of the present work is to reveal that PIs are more than just measurements of performance. There is a need for a commonly accepted approach that supports the development of a consistent PI system within the inland waterway industry.
Simulation-Based Network Maintenance Planning and Scheduling
Authors: Wang Shiaau-Lir , Yang Ning , Schonfeld Paul
Published: September 2009

Lock deterioration in a waterway network requires timely maintenance to maintain navigability and regular lockage service. Locks degrading over time have reduced capacities and increased service times. Because demand responds to service changes, the objective function maximizes the overall net benefits rather than the minimization of costs. To maximize the net benefits, it is important to schedule maintenance that preserves lock conditions above threshold values, provides minimum acceptable service, and reduces the risks of serious failures. With constrained budgets, network-level maintenance can be scheduled over a planning horizon. A waterway model that combines simulation and optimization was developed to allocate maintenance funds and to schedule maintenance tasks optimally. Numerical cases are evaluated by parallel processing. The promising demonstration of simulation-based optimization shows the applicability of the proposed methodology to network-level and component-level maintenance planning and scheduling.
Calibration of the Highway Safety Manual's Accident Prediction Model for Italian Secondary Road Network
Authors: Martinelli Filippo , La Torre Francesca , Vadi Paolo
Published: September 2009

The forthcoming first edition of the Highway Safety Manual (HSM) will introduce safety predictive models both for road segments and intersections. A key issue for allowing HSM to become a standard for road owners and managers worldwide is the transferability of the predictive models to different networks. The application of the calibration procedure of the HSM model to different countries has been evaluated, with all practical and potential application problems outlined. In this study, the calibration procedure of the HSM model has been applied to the road network of the Italian province of Arezzo to evaluate the effective transferability of this methodology to a region characterized by a different environment and different road characteristics, driver behavior, and crash reporting systems than those on which the HSM models have been developed. The considered road network covers 1,300 km of rural two-lane highways located in the Arezzo province, and a 3-year (2002–2004) accident database has been used. The considerable difference between the road network of the Italian province of Arezzo and the one of Minnesota, for which the HSM model has been developed, causes practical application problems, mainly related to segmentation and over-estimation of curvature effects, which are discussed in the paper. Four approaches to define the calibration factor have been applied and discussed to determine the most effective one. Finally, this work points out the problems related to the identification of data needs and necessary treatments for the HSM model calibration and application.
Speed and Safety
Authors: Hauer Ezra
Published: September 2009

The speed at which people elect to travel is affected by vehicle and road design; by limits to speed and enforcement of those limits; by traffic control, signs, and markings; and so forth. The speed at which people travel, in turn, affects road safety. In this context two questions arise: ( a) How is the evolution of speed over time and space affected by what drivers do? ( b) How does speed affect safety? This paper reviews what is known, notes the gaps in knowledge, and describes where opinions differ and why. Unfortunately, despite decades of speed measurement and monitoring, the evolution of speed over time is poorly documented, and the understanding of what drives the evolution is largely missing. It is known that speeds evolve over time, but not why; it is known that there is some spillover of the change from one road to another, but its size or extent cannot be predicted. This is a neglected field of inquiry. More is known in answer to Question b. There can be no reasonable doubt that if speed increases while other conditions (vehicles, roads, medical services) remain unchanged, the accidents that occur will tend to be more severe. However, the prevalent and strongly held belief that the greater the speed, the higher is the probability that accidents will occur is, at present, not well supported by research. Even so, given a change in mean speed, one can predict the consequences in injuries and fatalities and this paper discusses how to do so.