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This paper investigates the quantitative characteristics of the vehicle arrival pattern on highways. Inspired from a remarkable finding on data network traffic that most data packet arrival patterns follow the self-similar process as opposed to the classical Poisson process, this paper aims to explore whether the vehicle arrival pattern on highways exhibit the self-similarity property and the corresponding time headway distribution it obeys. By using real highway traffic data provided by the Texas Department of Transportation, United States, this paper examines the existence of self-similarity characteristics on these vehicle arrival data. This is done by estimating the Hurst parameter, which is an index for self-similarity testing. Hypothesis testing for the Hurst parameter estimation shows that the highway vehicle arrival pattern under moderate to heavy traffic conditions exhibit the self-similarity behavior. Then, using the headway data recorded from the Federal Highway situated in Kuala Lumpur of Malaysia, this paper further demonstrates that the time headway of vehicles on the highways follows the heavy-tailed distribution rather than the classical exponential distribution. These two novel findings not only shed some light on the existence of a new distribution to describe the vehicle arrival pattern but also enrich the studies on traffic flow theory. [ABSTRACT FROM AUTHOR]

Trucks move around 70% of the freight weight in the United States. The combination of increased commercial motor vehicle traffic, tighter delivery schedules, and federally regulated limits on driving time lead to a nationally recognized problem on interstate highways in the United States, i.e., increased demand for commercial truck parking. Unavailability of sufficient parking spaces at rest areas results in illegal and unsafe parking at entrance/exit ramps, and other unauthorized areas. The research reported in this paper, funded by the Florida DOT, sought to understand the truck parking problem in Florida, determine the supply and demand characteristics for commercial truck parking, assess technology that can be used to improve parking management, and conduct a pilot project to test a smart truck parkingmanagement technology to make better utilization of commercial parking spaces at public rest areas. [ABSTRACT FROM AUTHOR]

This paper is concerned with implementation challenges related to using dynamic traffic assignment on actual large urban networks. Such challenges include the manipulation of network and demand data, the modeling of turning movements, the efficient computation of link travel times, and the handling of complex path data. The basic simulation-assignment based approach introduced by Mahmassani et al. in 1993 was enhanced to address the challenges outlined above. The model is used on applications presently performed by agencies with static transportation planning models, such as infrastructure improvements, demand management, and congestion pricing. In addition, various applications that are difficult to perform with static models are explored, such as the evaluation of Intelligent Transportation Systems technologies. Computational tests are performed on the Columbus, Ohio urban network and the results are analyzed. [ABSTRACT FROM AUTHOR]

The article discusses the mission and objectives of The Institute of Management Sciences (TIMS). The author discusses the two-person game theory of John von Neumann, and the fact that von Neumann's breakthroughs came from his study of quantum mechanics rather than management science. The author states that von Neumann was one of the earliest scientists to recognize the importance of electronic computers. Leslie Edie, of the Port of New York Authority, was awarded the Lanchester Prize by the Operations Research Society of America for his paper on "Traffic Delays at Toll Booths." An article by Smiddy and Naum that addresses the evolution of management science in the U.S. is cited. Frederick Winslow Taylor is referenced for promoting an archaic, engineering-based form of management science.

Hybrid electric vehicles (HEVs) are considered to be one of the energy-efficient technologies for near-term sustainability of the transportation sector. Over the years, research has focused on improving fuel economy (FE) for a given drive cycle, but FE variability over a realistic range of real-world driving patterns has been generally overlooked, and this can lead to FE benefits not being fully realized in real-world usage. No systematic methodology exists to reduce FE variability by design optimization of powertrain components. This study proposes a methodology of powertrain component optimization to reduce the FE variability due to variations in driving patterns. In the proposed methodology, powertrain components are optimum over a range of driving patterns of different traffic conditions and driving styles simultaneously. The proposed methodology demonstrates the potential to reduce FE variability by up to 34% over six driving patterns of different traffic conditions and driving styles. [ABSTRACT FROM PUBLISHER]

Abstract: This paper reviews road safety performance in the United States. The paper develops a framework for assessing dimensions of road safety, and analyzes the importance of economic factors, travel patterns, demographics, road/traffic/vehicle technology, driver behavior, and public policy. Issues and challenges for future road safety research are discussed. [Copyright &y& Elsevier]

Abstract: The persistent infrastructure underinvestment coupled with a significant growth in commercial and non-commercial transportation demand has rendered the US transportation infrastructure unprepared for current and future demands. A significant improvement in the condition of the US transportation infrastructure must be grounded on a more sustainable and proactive approach to address the existing gap between short-term commitments and long-term needs. This paper demonstrates in quantitative terms the value of long-term investments to overcome the historical impediments to infrastructure rehabilitation, including the need for a proactive political structure that compensates for the apparent lack of public accountability, and for the poor understanding of the socio-economic effects caused by transportation infrastructure failures. Such a process could avoid impending catastrophes. This paper presents a modeling paradigm that accounts for multiple stakeholder perspectives and relates the formulation of public policy to a long-term horizon through the modeling of the transportation infrastructure as a system of systems. The methodology enables involved stakeholders and decision makers to visualize their shared interests and to promote coordinated individual decisions in order to achieve a more acceptable level of the overall system of systems objectives. To illustrate the relevance of the proposed modeling approach, we apply it to a bridge maintenance problem and we discuss the synthesis of existing engineering practice with socio-economic factors that aids in streamlining long-term infrastructure goals with immediate short-term needs. The insights obtained from the proposed system of systems methodological approach point to the need to adopt a more forward-looking and collaborative public policy for infrastructure maintenance. [Copyright &y& Elsevier]

Local public works agencies and state departments of transportation play a major role in disasters and other emergencies. Their maintenance and operations (field force) staffs constitute the most visible and vital element, especially in the response and recovery phases. They are among the first to respond and clear roadways so that police, fire, emergency medical, and utilities vehicles can access stricken areas. Field forces also assist with rescue, evacuation, and sheltering and provide temporary traffic control, perimeter security, animal control, transportation of supplies and equipment, on-site vehicle service, debris management, and restoration of infrastructure. The wide range of their capabilities is a valuable component in nearly any type of crisis. Homeland Security Presidential Directive 8 of 2003 included public works as "emergency responders." However, overall acceptance and recognition by primary responder disciplines as equals in emergency management are still lacking. Even public works officials must raise awareness within their own discipline that emergency management is just as important as other functions. This paper examines the evolving mission of public works in emergency management. [ABSTRACT FROM AUTHOR]

This paper presents an investigation into the current U.S. practice regarding the use of channelized right-turn lanes at signalized intersections, the type of traffic control used, and the safety experience of highway agencies. The study involved a literature review and a practice survey, which was distributed to all state and selected local agencies in the United States. The literature review revealed the overall lack of knowledge about the operational and safety aspects of channelized right-turn lanes explaining, to a large extent, the lack of guidance in practice. Survey results suggest a heavy reliance on engineering judgment by highway agencies in the use of channelized right-turn lanes and the selection of traffic control. Further, results confirmed a general perception in practice about the safety benefits of signal control at channelized right-turn lanes, despite the fact that such benefits were not supported by studies or statistics. The study emphasized the need for further research on the operational and safety aspects of this right-turn treatment at intersections. [ABSTRACT FROM AUTHOR]

Stop signs are the primary form of traffic control in the United States. However, they have a tendency to be much less effective than other forms of traffic control like traffic lights. This is due to their smaller size, lack of lighting, and the fact that they may become visually obscured from the road. In this paper, we offer a solution to this problem in the form of a mobile application implemented in the Android platform: Stop Watcher. It is designed to alert a driver when they are approaching a stop sign using a voice notification system (VNS). A field test was performed in a snowy environment. The test results demonstrate that the application can detect all of the stop signs correctly, even when some of them were obstructed by the snow, which in turn greatly improves the user awareness of stop signs. [ABSTRACT FROM AUTHOR]

Although freeway traffic system is conducted with a repeatable pattern day-to-day, the initial volume/or speed and the desired density of the traffic flow may vary with days due to the external disturbances. In this paper, a new linear data-model based adaptive iterative learning control (LDM-AILC) is proposed to address ramp metering in a macroscopic level freeway environment. A linear data-model is developed for the nonlinear macroscopic traffic flow model by introducing an equivalent dynamical linearization approach in the time domain. Then the LDM-AILC is designed with a feedback control law and a parameter updating law. The proposed scheme is data-driven intrinsically, where only the input and output data are required for the controller design and analysis. The convergence is shown by rigorous analysis without any identical conditions exposed on both the initial state and the reference trajectory. Extensive simulation results are provided to verify the effectiveness of the proposed LDM-AILC. [ABSTRACT FROM AUTHOR]

The estimation of annual average daily traffic (AADT) is an important parameter collected and maintained by all US departments of transportation. There have been many past research studies that have focused on ways to improve the estimation of AADT. This paper builds upon previous research and compares eight methods, both traditional and cluster-based methodologies, for aggregating monthly adjustment factors for heavy-duty vehicles (US Department of Transportation Federal Highway Administration (FHWA) vehicle classes 4-13). In addition to the direct comparison between the methodologies, the results from the analysis of variance show at the 95% confidence level that the four cluster-based methods produce statistically lower variance and coefficient of variation over the more traditional approaches. In addition to these findings - which are consistent with previous total volume studies - further analysis is performed to compare total heavy-duty monthly adjustment factors, both directions of traffic, with direction-based monthly adjustment factors. The final results show that the variance as well as the coefficient of variation improve on average by 25% when directional aggregate monthly adjustment factors are used instead of total direction. [ABSTRACT FROM AUTHOR]

This paper presents a new integer programming (IP) model for large-scale instances of the air traffic flow management (ATFM) problem. The model covers all the phases of each flight--i.e., takeoff, en route cruising, and landing--and solves for an optimal combination of flow management actions, including ground-holding, rerouting, speed control, and airborne holding on a flight-by-flight basis. A distinguishing feature of the model is that it allows for rerouting decisions. This is achieved through the imposition of sets of "local" conditions that make it possible to represent rerouting options in a compact way by only introducing some new constraints. Moreover, three classes of valid inequalities are incorporated into the model to strengthen the polyhedral structure of the underlying relaxation. Computational times are short and reasonable for practical application on problem instances of size comparable to that of the entire U.S. air traffic management system. Thus, the proposed model has the potential of serving as the main engine for the preliminary identification, on a daily basis, of promising air traffic flow management interventions on a national scale in the United States or on a continental scale in Europe. [ABSTRACT FROM AUTHOR]

A review of the experience of 23 states on the use and effectiveness of cable median barriers is presented. As of 2007, 23 states have installed more than 4,183 km (2,600 mi) of cable median barriers. Experiences of the pioneering states, such as New York, Missouri, Washington, Oregon, North Carolina and Arizona that initiated the utilization of cable median barrier in the United States are included in this paper. Results of the review show that the use of cable median barriers in depressed medians with moderate slopes had a significant effect on the reduction of cross-median crashes in many states. While these results are encouraging, occasional fatal crossover crashes penetrating the cable barrier still demand attention and improved techniques or procedures for selecting or locating cable median barrier will continue to evolve. [ABSTRACT FROM AUTHOR]

The continuing growth of international container trade has created capacity problems at major US ports, and the truck-based freight transportation has caused a deterioration of traffic congestion on important US transportation corridors. Using inland and coastal waterways, short sea shipping (SSS) can provide an improvement to these problems. Furthermore, SSS offers many additional benefits for the environment, the economy and society as a whole. Both the US Department of Transportation and the European Commission actively support SSS as an alternative, environmentally friendly mode of transportation. However, there are obstacles, administrative barriers and challenges that should be addressed. Several successful operations on both sides of the Atlantic make a strong case in favour of SSS. SSS can develop customized and technologically advanced solutions that will further integrate it into the intermodal transportation chain and will improve its image among shippers as a mode that can provide reliable door-to-door transportation. This paper reviews several studies on the subject and discusses the latest developments on SSS in the US and in Europe. It also addresses the major issues and the benefits of SSS and examines the prospects for potential short sea operations in the US. Finally, it proposes research opportunities for a multimodal transportation system that will include a short sea component. [ABSTRACT FROM AUTHOR]

The paper explores relationships between seven dimensions of land use in 1990 and subsequent levels of three traffic congestion outcomes in 2000 for a sample of 50 large US urban areas. Multiple regression models are developed to address several methodological concerns, including reverse causation and time-lags. Controlling for prior levels of congestion and changes in an urban area's transport network and relevant demographics, it is found that: density/continuity is positively related to subsequent roadway ADT/lane and delay per capita; housing centrality is positively related to subsequent delay per capita; and housing–job proximity is inversely related to subsequent commute time. Only the last result corresponds to the conventional wisdom that more compact metropolitan land use patterns reduce traffic congestion. These results prove two points: that the choice of congestion measure may substantively affect the results; and that multivariate statistical analyses are necessary to control for potentially confounding influences, such as population growth and investment in the transport network. [ABSTRACT FROM AUTHOR]

TransGuide is San Antonio’s multifunctional citywide center that manages traffic through surveillance, incident detection/management, and dissemination of traffic information. This paper reviews automatic incident detection technologies deployed in San Antonio freeways and managed by TransGuide. Traffic and incident data collected from the San Antonio network are used to compare the performance of inductive loop detectors (ILDs) and automatic vehicle identification (AVI) for automated incident detection. California No. 8 and the Texas algorithms were calibrated and tested using the ILD data collected for incident detection. The upper confidence limit algorithm and the Texas algorithm were calibrated and tested using the AVI data collected. When traffic and incident data from the San Antonio network are processed by the four different algorithms, the California No. 8 algorithms applied to ILD data performed best in terms of detection rate and false alarm rate. Automated incident detection (AID) is not currently worth implementing in the AVI system studied, but AID based on AVI data is generally feasible with denser tag penetration and sensor installation. [ABSTRACT FROM AUTHOR]

Evaluating the performance of a detection and warning system designed specifically to detect and warn no-passing zone violations on vertical curves of two-lane rural roads is the focus of this paper. The evaluation is mainly based on the unique simulation developed for that purpose. Many roadway, vehicle, and driver-related parameters were introduced in this simulation to reflect as close as possible what is occurring in the real world. More than 19,500 violation case simulation runs were made for the base scenario to reflect and calibrate the actual conditions of the parameters involved. The simulation runs were made for both “with” and “without” the warning system cases. The simulation outcome for the “without the system” case was very close to the actual real-world condition (1.41 versus 0.71 crash per year). The simulation runs of the “with the system” case showed also that the system could virtually eliminate all head-on collisions, should the violators obey the early warning messages displayed. Eleven sensitivity tests showed that the simulation is robust in describing the system performance. An economic feasibility analysis revealed a high benefits–cost ratio of 38.9, and modified internal rate of return of 65%. [ABSTRACT FROM AUTHOR]

This paper attempts to provide some insight into the structure of' a large class of fleet scheduling problems. Scheduling under fixed due date constraints is shown to be easily solved using a new formulation of the problem. Scheduling under flexible due date constraints is shown to be inherently complex, and strong evidence is given for asserting that no efficient (polynomial bounded) algorithm, exists for solving this problem exactly. A fast heuristic approach is described which has worked well in some school bus scheduling applications. [ABSTRACT FROM AUTHOR]

Worsening highway congestion is a challenge to megaregional competitiveness; changing regional geographies and development location decisions, among other factors, demand that public policy responses go beyond traditional demand-management approaches. Congestion-pricing has been suggested as a remedy. In this paper, the writers analyze the outcomes of multiple congestion-pricing approaches for the capital megaregion that spans the following five metropolitan planning organization regions: (1) Washington (District of Columbia, Maryland, and Virginia), (2) Baltimore (Maryland), (3) Wilmington (Delaware), (4) Fredericksburg (Virginia), and (5) Frederick (Maryland), in addition to counties in the adjoining states of New Jersey, Pennsylvania, and West Virginia in the United States. Using a megaregional travel-demand model, the writers incorporate different values-of-time (VOTs) for travelers under different conditions. However, unlike past approaches, the writers' VOT estimates go beyond income categories and include trip purposes across a number of scenarios. The writers demonstrate that adding the trip purpose to congestion-price determination provides added insight both at the megaregional level and for individual subregions. The results of this paper show how highway users respond differently and (in some cases) in unexpected ways to congestion charges when trips in accordance with income and purpose are assigned a unique VOT. The findings reported in this paper provide engineers, planners, and policymakers with a new analytical approach to measuring traveler elasticity to tolls while demonstrating the complexity involved with road-pricing mechanisms. The writers conclude with implications for adopting this approach and ideas for implementing them in a complex institutional setup. [ABSTRACT FROM AUTHOR]

Problem, research strategy, and findings: Planners commonly recommend compact development in part as a way of getting people to drive less, with the idea that less driving will lead to more sustainable communities. Planners base their recommendations on a substantial body of research that examines the impact of compact development on driving. Different studies, however, have found different outcomes: Some studies find that compact development causes people to drive less, while other studies do not. I use meta-regression analysis to a) explain why different studies on driving and compact development yield different results, and b) combine different findings from many studies into reliable statistics that can better inform planning practice. I address the following questions: Does compact development make people drive less, and if so, how much less? I find that compact development does make people drive less, because most of the compact development features I study have a statistically significant negative influence on driving. The impact, however, is fairly small: Compact development features do not appear to have much influence on driving. My findings are limited to some extent because they are derived from small sample sizes. Takeaway for practice: Planners should not rely on compact development as their only strategy for reducing driving unless their goals for reduced driving are very modest and can be achieved at a low cost. [ABSTRACT FROM PUBLISHER]

Approximately 11% of bridges in the United States are categorized as structurally deficient and there is a marked need of more accurately evaluating true structural capacity. Structural Health Monitoring (SHM) systems can provide a timely indication of the need for maintenance, repair, rehabilitation and replacement of bridges and can greatly improve the apportionment and management of limited resources. This paper presents an Automated Ambient Traffic (AAT) approach for determining load rating of bridges monitored by the BECAS SHM system under ambient traffic. The AAT approach was developed through a process integration of truck detection, bridge model calibration, and bridge load rating: (1) the quasi-static bridge strain response and the characteristics of associated trucks are collected; (2) multiple trucks are randomly sampled from a historic Weigh-In-Motion (WIM) database; and (3) for each combination of strain response and truck selection, an Finite Element (FE) model is calibrated and used to calculate a load rating. Sampling strategies were discussed for appropriately quantifying the influence of uncertainties of truck characteristics on the calibration and load rating results. To demonstrate this approach, a sample three-span, five-girder, and two-lane steel girder/concrete deck (I-80) bridge was utilized. A load rating of the I-80 Bridge using the Traditional Known Truck (TKT) approach was performed to provide benchmark results. The results of the calibration and load rating using the AAT approach were derived using three different sampling strategies and compared to those using the TKT approach. The sampling strategy, selecting strain response with a spectrum of higher peak girder strains, associated trucks with a spectrum of higher gross vehicle weights, and two truck events on south and north lanes respectively for a calibration, resulted in the best calibration and load rating results. It was concluded that the AAT approach using the BECAS SHM system is a reliable method for continuously estimating the load carrying capacity of bridges. [ABSTRACT FROM AUTHOR]

Users of International Land Ports of Entries (LPOEs) at the US – Mexico border experience excessive wait times on a daily basis. This contributes to the increased transportation costs, and also generates health and environmental problems in border regions. Traffic simulation models are effective tools for evaluating passenger vehicle, pedestrian and commercial traffic operations. These tools can be used to assess various scenarios and visualize current traffic conditions. Results obtained from these tools should be taken into account in congestion relief decision making processes. The research team developed, calibrated and validated three traffic models of the Ysleta-Zaragoza LPOE using three different software packages (i.e., TransModeler, VISSIM, and Aimsun). This paper presents advantages and disadvantages of each tool when modeling international LPOEs. Results presented herein can be used by practitioners to decide which tool should to be used for modeling LPOEs at the U.S. – Mexico border. [ABSTRACT FROM AUTHOR]

Abstract: Motor vehicle crashes result in millions of injuries and thousands of deaths each year in the United States. While most crash research datasets use Abbreviated Injury Scale (AIS) codes to identify injuries, most hospital datasets use the International Classification of Diseases, version 9 (ICD-9) codes. The objective of this research was to establish a one-to-one mapping between AIS and ICD-9 codes for use with motor vehicle crash injury research. This paper presents results from investigating different mapping approaches using the most common AIS 2+ injuries from the National Automotive Sampling System-Crashworthiness Data System (NASS-CDS). The mapping approaches were generated from the National Trauma Data Bank (NTDB) (428,637 code pairs), ICDMAP (2500 code pairs), and the Crash Injury Research and Engineering Network (CIREN) (4125 code pairs). Each approach may pair given AIS code with more than one ICD-9 code (mean number of pairs per AIS code: NTDB=211, ICDMAP=7, CIREN=5), and some of the potential pairs are unrelated. The mappings were evaluated using two comparative metrics coupled with qualitative inspection by an expert physician. Based on the number of false mappings and correct pairs, the best mapping was derived from CIREN. AIS and ICD-9 codes in CIREN are both manually coded, leading to more proper mappings between the two. Using the mapping presented herein, data from crash and hospital datasets can be used together to better understand and prevent motor vehicle crash injuries in the future. [Copyright &y& Elsevier]

Abstract: Over the past twenty-five years, more workers in the United States have been given the option of flexible work schedules, which are designed to redistribute commuter traffic over the course of a day by allowing employees to vary their arrival and/or departure times. This paper examines whether and to what degree access to flexible work schedules affects the departure times of commuters in the two largest and most congested areas of California: the Los Angeles and San Francisco regions. Trip data were obtained from the 2009 US National Household Travel Survey (NHTS). The results of this study show that people who have access to flexitime preferred later departure times rather than earlier times. Workers with flexible schedules were 3.30% less likely to depart before peak hours, 4.11% less likely during peak hours, and 7.41% more likely afterwards. Based on these findings, government agencies and private firms in regions with severe traffic congestion problems may consider adopting alternative work schedules. [Copyright &y& Elsevier]

In 2011, the Institute of Transportation Engineers (ITE) entered into a cooperative agreement with the Federal Transit Administration aimed at improving the integration of transit priority treatments on urban street networks. To address this issue, ITE in a partnership with the American Public Transportation Association conducted two peer-exchange-based workshops to educate practitioners, share experiences and lessons learned, identify barriers, and recommend potential solutions. The workshops were specifically targeted at fostering relationships between transit and traffic engineeringprofessionals, with an overarching goal of improving the integration of transit operations and traffic control strategies. This article highlights the issues discussed and input received. Workshop proceedings and a more detailed white paper will be available on the ITE website in January 2013. [ABSTRACT FROM AUTHOR]

This paper proposes an en route speed reduction to complement current ground delay practices in air traffic flow management. Given a nominal cruise speed, there exists a bounded range of speeds that allows aircraft to fly slower with the same or lower fuel consumption than the nominal flight. Therefore, flight times are increased and delay can be partially performed in the air, at no extra fuel cost for the operator. This concept has been analyzed in an initial feasibility study, computing the maximum amount of delay that can be performed in the air in some representative flights. The impact on fuel consumption has been analyzed, and two scenarios are proposed: the flight fuel remains the same as in the nominal flight, and some extra fuel allowance is permitted in order to face uncertainties. Results show significant values of airborne delay that may be useful in many situations, with the exception of short hauls where airborne delay may be too short. If cruise altitude is changed, the amount of airborne delay increases, since changes in cruise speed modify the optimal flight altitudes. From the analyzed flights, a linear dependency is found relating the airborne delay with the amount of extra fuel allowance. [ABSTRACT FROM AUTHOR]

Abstract: Contracted service comprises a significant proportion of total operating expenses in the provision of fixed-route bus transit service in the US. Despite its importance, the literature on the economic effects of transit service contracting has been limited to only a few studies since the mid-1990s, and is inconclusive due to problems with the nature and methodology of the past studies. This paper examines how the cost efficiency of providing fixed-route bus transit service varies by the degree of contracting. I make several improvements to previous studies and conduct a regression analysis that: (1) addresses the endogeneity problem between the contracting decision and cost efficiency, (2) differentiates between agencies that contract out only a portion of service from those that contract out all service, (3) takes into account the moderating effects of several factors on the effect of contracting on cost efficiency, and (4) uses a relatively larger set of cross-sectional time-series data constructed from the National Transit Database from 1992 to 2000. The analysis results show that the combined effects of contracting lower operating costs by $4.09 and $2.89 per vehicle hour for partial and full-contracting agencies, respectively, in the average case. These average cost savings translate into 7.8% and 5.5%, using the average operating cost per vehicle hour of $53.06. However, this improvement is not universal, because the effects of contracting on cost efficiency vary by factors such as peak-to-base ratio, agency size, the wage gap between bus operators in the public and private sectors, and agency type. [Copyright &y& Elsevier]

Abstract: Enhancing airport runway safety is a difficult problem because runway accidents are rare events. Nonetheless, investments are being directed at improving safety for US airport ground traffic control systems. This paper shows that under these circumstances it is difficult to assess and measure the added safety offered by new replacement systems. We develop a framework for introducing and sequencing system improvements to provide greater assurances in enhancing safety. This framework shows how a new method can first be introduced as a secondary system, to test and verify its efficacy prior to its adoption as a primary system. [Copyright &y& Elsevier]

The article presents a reprint of "Vehicle Emissions and Level of Service Standards: Exploratory Analysis of the Effects of Traffic Flow on Vehicle Greenhouse Gas Emissions," by Rafael Cobian and colleagues which appeared at the 88th Annual Meeting Compendium of Papers of the U.S. Transportation Research Board. It focuses on a travel demand forecasting model that quantifies level of service (LOS) policies and traffic emissions. It also suggests the most efficient operating policy in the study.

Immigrants account for a majority of recent urban population growth in the United States, and for much economic growth as well. This is expected to continue for the next several decades. The foreign-born are much more likely to use transit, carpool, walk, and bicycle, particularly in their first few years of living in the United States. These trends represent challenges and opportunities for transportation and land use planners to increase the environmental sustainability of population growth, use existing transportation systems to their maximum efficiency, and support economic development. But doing so depends on anticipating the travel demands of varying immigrant groups, and those demands in turn depend on their employment and residential location choices. The authors present the most current data available on these trends, summarize research literature, and identify the major research questions needing answers to understand how to accommodate the travel demands of immigration-driven population growth. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, we present a stochastic integer programming model for managing air traffic inbound to an airport when both the airport itself and its approach routes are subject to adverse weather. In the model, ground delay decisions are static, while those on rerouting are dynamic. The decision variables in the model are aggregate number of flights planned to arrive at various capacity constrained resources. The model does not directly assign arrival times to individual flights. Therefore, in context of Collaborative Decision Making, which is the governing philosophy of the air traffic management system of the United States, the solutions from the dynamic rerouting model can be directly fed to some resource allocation algorithm that assigns routes and release times to individual flights or to the airlines who operate them. When adverse weather blocks or severely limits capacity of terminal approach routes, rerouting flights onto other approaches yields substantial benefits by alleviating high ground delays. Our experimental results indicate that making rerouting decisions dynamically results in 10–15% delay cost reduction compared to static rerouting, and about 50% less delay cost compared to a “pure” ground holding strategy (i.e., no rerouting). In contrast to static rerouting, the dynamic rerouting capability results in making rerouting decisions that are better matched to realized weather conditions. Lower total expected delay cost is achieved by delaying the rerouting decisions for flights until they reach the divergence point between alternative routes, and hence exploiting updated information on weather while making those decisions. In cases where the airport is the main, but not the only, bottleneck, the dynamic rerouting model may assign higher ground delays so that the rerouting decisions can be deferred until more information on en route weather becomes available. [Copyright &y& Elsevier]

Transportation engineering constitutes a required portion of the civil engineering curriculum at over three-fourths of undergraduate civil engineering programs in the United States. The input of practicing transportation engineers is a critical source of information in determining the content of the first course in transportation engineering. A new survey was conducted in which respondents ranked 31 potential course topics by importance. The results are compared to a similar survey conducted 20 years before to determine which topics have increased in importance, which have become less critical to cover, and which continue to remain of high priority. Topics such as traffic safety and traffic flow characteristics are of considerably higher priority today than 20 years ago, while topics such as geometric design of highways and highway capacity studies continue to be of great importance. Preparation for follow-up and graduate coursework, for the Fundamentals of Engineering and Professional Engineer examinations, and issues of local setting are also considerations in determining the content of the first course in transportation engineering. [ABSTRACT FROM AUTHOR]

Abstract: This paper studies the properties and performance of a new measure of accessibility, called the activity-based accessibility (ABA) measure, and compares it to traditional measures of accessibility, including isochrone, gravity and utility-based measures. The novel aspect of the ABA is that it measures accessibility to all activities in which an individual engages, incorporating constraints such as scheduling, and travel characteristics such as trip chaining. The ABA is generated from the day activity schedule (DAS) model system, an integrated system based on the concept of an activity pattern, which identifies the sequence and tour structure among all the activities and trips taken by an individual during a day. A byproduct is an individual’s expected maximum utility over the choices of all available activity patterns, and from this the ABA is derived. The ABA is related to the logsum accessibility measures frequently derived from destination and mode discrete choice models. The key difference is that it is generated not by examining a particular trip, but by examining all trips and activities throughout the day. A case study using data from Portland, Oregon, demonstrates the rich picture of accessibility made available by use of the ABA, and highlights differences between the ABA and more traditional measures of accessibility. The ABA is successful in (a) capturing taste heterogeneity across individuals (not possible with aggregate accessibility measures), (b) combining different types of trips into a unified measure of accessibility (not possible with trip-based measures), (c) reflecting the impact of scheduling and trip chaining on accessibility (not possible with trip-based measures), and (d) quantifying differing accessibility impacts on important segments of the population such as unemployed and zero auto households (not possible with aggregate measures, and limited with trip-based measures). [Copyright &y& Elsevier]

The Federal Aviation Administration's effort to automate air traffic control (ATC) requires that the functionality provided today be captured in future systems. We report the first quantitative naturalistic observation of paper flight progress strip interactions during operational use. Strip use was similar in a variety of situations, but some uses varied as a function of altitude, staffing, or the cooperative style used by controller teams. Design of automation should proceed by prioritizing changes based on frequency of use and importance and should ensure that an effective method of interacting with flight information is incorporated. In addition to applied relevance to the ATC domain, the results touch on several theoretical concerns relevant to dynamic environments. Actual and potential applications of this research include the establishment of a database of strip activity and an arsenal of information valuable to system designers. [ABSTRACT FROM AUTHOR]

This paper reviews the legal status of traffic calming in the US. It covers case law relating to legal authority, tort liability, and takings. It also covers damage claims against 20 localities that have been particularly active in traffic calming. [ABSTRACT FROM AUTHOR]

This paper explores impediments to context-sensitive design of main streets, and suggests ways of overcoming them. It is based on a guidebook for the New Jersey Department of Transportation titled Flexible Design of New Jersey's Main Streets. Contrary to conventional wisdom, minimum design values in the American Association of State Highway and Transportation Officials' A Policy on Geometric Design of Highways and Streets (AASHTO's 2001 Green Book) do not appear to constrain main street design. Nor do tort liability considerations in most states, primarily because of broad design immunity under state statutes and case law. From case studies conducted for this project, the real impediments to context-sensitive design appear to be: state design standards in excess of AASHTO minimums, and in excess of what is required for driver safety in low-speed environments; minimum level-of-service standards adopted for driver convenience, which may be less important on main streets than pedestrian safety and comfort; over-reliance on typical sections from state roadway design manuals, when multiple cross sections tailored to abutting land uses would be more appropriate; and reluctance to seek design exceptions for purposes of "context savings," only for purposes of cost savings. Additional impediments include application of new construction standards to 3R and reconstruction projects, even when a street's history suggests no safety problem; misclassification of streets as rural and application of rural design standards to them, when they in fact run through small urban places; misclassification of streets as arterials, when bypasses and other parallel improvements have caused main streets to function as local streets; and reluctance of state DOTs to assume maintenance responsibilities for street trees, landscaped medians and bulbouts, textured crosswalks, and similar common main street improvements. Case studies from Albuquerque, NM; Anchorage, AK; Brooklyn, CT; Saratoga... [ABSTRACT FROM AUTHOR]

Increased peak period congestion causes the peak to spread. The travel time impact of congestion is mitigated for some travelers, but the inconvenience of traveling at a less preferred time also has a cost. Alternatively, increases in highway supply narrow the peak. This reduces the travel time savings, but it generates a benefit for those traveling closer to their preferred times. This benefit from roadway supply increases has been ignored in practical applications, largely due to the difficulty of quantifying the effect. This paper reports on an attempt to quantify the peak narrowing effect of increased highway supply. For the morning commute, the model estimates that each 1% increase in lane-miles per thousand population results in workers departing from home about 0.06-0.09% closer to the peak time.

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Historically, there has been considerable debate over appropriate methods for determining optimum investment in inland waterway navigation. Recent controversy has centered on a U.S. Army Corps of Engineers' study into the need for additional lock capacity at selected Upper Mississippi and Illinois Waterway locks. In this paper, we illustrate the use of spatial grain models (quadratic programming models) for estimating benefits from inland waterway navigation improvements. The illustrated methodology would appear to circumvent some of the recent criticism directed at the U.S. Army Corps of Engineers' study. [ABSTRACT FROM AUTHOR]

Behind all debates over the adequacy of highway revenues lies the tricky issue of how much money states and the federal government ought to spend on highways. States and the federal government have historically tried to determine revenue needs with technical reports known as "needs assessments." These studies usually conclude with a dollar figure that represents the revenue required to bring all roads up to some set of maintenance and performance standards. Even though a great deal of careful technical analysis can go into needs analyses, most do not actually address the question of what total level of spending would be best. Needs assessments typically identify how much money would be required to meet certain standards or to build desired lists of projects, but generally do not address whether or not such standards or lists are optimal. Drawing on examples from California, this paper reviews the evolution of both highway needs studies and fluctuations in highway funding over the past half century. We find, despite efforts to increase the rigor of highway needs analyses, needs studies are often simply "wish lists" of locally popular projects. In particular, cost-benefit analyses have long been proposed to improve the quality and rigor of needs assessments, but have been very slow to be adopted. While a costbenefit approach to assessing highway needs would inevitably create winners and losers relative to current, engineering and ad hoc-oriented methods of assessing needs, such analyses would provide invaluable information to decision-makers in determining how to spend limited transportation resources most effectively and efficiently. [ABSTRACT FROM AUTHOR]

Features a study which described a novel traffic control system at two-lane freeway work zone entries developed by the Indiana Department of Transportation and Purdue University in West Lafayette. Brief explanation of the Indiana Lane Merge System (ILMS); Presentation of research results prior to implementation; Guidelines for the setting of the system; Implications of the study.

Accurate predictions of highway accident frequency may help traffic engineers design and test solutions for the improvement of highway safety. However, accident frequency prediction is by no means an easy task due to the large number of factors affecting accident occurrence and the complicated interactions among them. Many studies have been conducted to uncover the relationship between the roadway environment and corresponding accident frequencies. These studies used statistical approaches such as linear regression analysis. The actual relationship between the roadway environment and corresponding accident frequencies has not been approximated with an acceptable certainty because it usually coincided with the mathematical models assumed by the researchers. This paper describes an application of a machine learning method, instance-based learning (IBL), to highway accident frequency predictions. We developed an IBL system and applied this system to highway accident frequency predictions. The data set used contains accident data from the main Utah highways for a 5-year period (19881992). Experimental results show that the IBL method is applicable to highway accident predictions and compared favorably with linear regression analysis and neural networks. [ABSTRACT FROM AUTHOR]