bluuebunny/crossref_metadata_2025 huggingface dataset:
Estimating a Statewide Transportation Infrastructure Funding Shortfall Using Long-Range Plans of Metropolitan Planning Organizations
Authors: Bond Alexander , Kramer Jeff
Published: December 2010

The information contained in long-range plans of metropolitan planning organizations (MPOs) can be amalgamated to estimate a statewide, metropolitan, 20-year transportation infrastructure funding shortfall. This article describes the methodology used to calculate such a shortfall in Florida, with information from all 26 MPOs in the state. The cost of needed projects and the dollar amount of anticipated revenue were extracted from each MPO plan. The difference between the two figures is the shortfall from that MPO. The methodology included steps taken to normalize the data for differing plan lengths, analysis base years, and rates of inflation. The results of the study show that Florida is expected to experience a $62.5 billion shortfall over the period 2005 to 2025. This is an annualized shortfall of $3.1 billion and represents a total statewide shortfall of 42.9%. The study concluded that Florida's shortfall has been increasing since the study was first conducted in 1997. Further, the data suggest the rate of increase may be accelerating. Shortfalls were not uniform in MPOs. In fact, they were observed to be smaller in MPO regions with slower population growth rates or dedicated sources of local funding such as impact fees or fully enacted local option gas taxes. Florida's transportation leaders have found this project useful in communicating the funding circumstances in the state. A statewide shortfall can help decision makers see how dramatic the shortfalls are and direct available resources toward urban areas.
Using Aggregated Federal Data to Model Freight in a Medium-Sized Community
Authors: Anderson Michael D. , Harris Gregory A. , Harrison Kevin
Published: December 2010

In most urban areas, freight volumes are not explicitly considered in the transportation planning process. This is primarily due to the proprietary nature of freight data, causing any freight data that are released to be highly aggregated. This paper examines a multitiered methodology to utilize freight data from a federally available, highly aggregated source within an urban planning model to accurately model truck transportation. A case study is included that demonstrates the modeling methodology for a medium-sized urban area, complete with international port, and contains validation results of the freight transportation in the area.
Integrated Multiple-Criteria Decision-Making Method to Prioritize Transportation Projects
Authors: Shelton Jeffrey , Medina Michael
Published: December 2010

Prioritization of transportation projects, a process of selecting projects for funding given multiple constraints, is cumbersome and time-consuming. This study presents a simplified methodology for ranking transportation projects with an integrated multiple-criteria decision-making (MCDM) process for prioritizing transportation projects when multiple decision makers present various opinions and biases. This study applies the analytic hierarchy process (AHP) and the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) to help multiple decision makers select transportation projects in an environment where vagueness and subjectivity are replaced with numerical values and processed in an automated fashion. The AHP is used to weigh a set of criteria by pair-wise comparisons, and TOPSIS is used to obtain final project rankings. Even though AHP and TOPSIS are widely accepted MCDM methods, few transportation policy boards have used this unique, integrated approach for ranking transportation projects. The El Paso, Texas, Metropolitan Planning Organization's Transportation Improvement Plan was used as a case study for this research.
Use of Intergovernmental Networks for Establishing a Collaborative Environment in Tribal Transportation Initiatives
Authors: Martinez Rebecca M.
Published: December 2010

The transportation project environment is complex as project stakeholders most often represent multiple governments because transportation systems are owned and operated by local, state, federal, and tribal governments. Surface transportation projects concerning tribal communities introduce additional complexity to the project environment as an additional layer of institutional relationships and protocols must be recognized. To achieve success on complex transportation projects, a collaborative environment must be established among project stakeholders. One strategy is to use intergovernmental networks for transportation planning and programming to address complex issues within the intergovernmental framework. These intergovernmental networks have been used in states across the nation, and specific cases that resulted from such networks have been documented. This paper investigates the intergovernmental network as a tool for creating a collaborative environment among project stakeholders. The paper also presents best practices by profiling states that have utilized intergovernmental networks for transportation planning as well as success stories resulting from intergovernmental utilization in each state.
Do Freeway Traffic Management Strategies Exacerbate Urban Sprawl?
Authors: Zhang Lei
Published: December 2010

The impact of highway capacity expansion on urban land use has been studied extensively. With the shift of transportation investment priorities from major capacity expansion projects to operational improvements, it has become increasingly important to understand the impact of transportation control measures such as traffic management and pricing on location choices. This paper explores the impact of traffic management strategies on land use patterns using the example of ramp metering. A regression-based transportation model is employed to capture changes in accessibility due to ramp metering on a highway network. A land use change indicator model then estimates how employment and residential density distributions shift in response to changing accessibility in several stylized urban areas with various initial land use patterns (e.g., monocentric and polycentric cities). Ramp metering is shown to improve accessibility in a nonuniform fashion. The resulting land use changes depend on the existing land use conditions. In monocentric cities, ramp metering exacerbates urban sprawl by encouraging residents to live further away from their workplaces, which produces avoidable excess travel. In polycentric cities with both nondominant central business districts and secondary employment centers, ramp metering actually encourages residents to relocate to areas near existing employment centers and therefore serves as an antisprawl measure. The weakest impact of ramp metering on land use is observed when an urban area has a perfect job-housing balance. Other interesting findings suggest that by making downtown areas more accessible, ramp metering may help revitalize declining city centers in congested cities and that business location decisions are not significantly affected by ramp metering.
Hedonic Analysis of Office Space Rent
Authors: Farooq Bilal , Miller Eric J. , Haider Murtaza
Published: December 2010

This paper presents the hedonic analysis of office space rent in the Greater Toronto area of Canada. The effects of accessibility, quality, location, and market conditions on rent are explored. Data indicate a high degree of spatial heterogeneity and clustering effects. Spatial analysis techniques are incorporated within the hedonic framework to capture these effects. Results indicate that access to transport infrastructure, distance from the central business district, and vacancy rate are significant in explaining variation in the rent.
Policy Evaluation in Multiagent Transport Simulations
Authors: Grether Dominik , Kickhöfer Benjamin , Nagel Kai
Published: December 2010

In democratically organized societies, the implementation of measures with regressive effects on welfare distribution tends to be complicated because of low public acceptance. The microscopic multiagent simulation approach presented in this paper can help to design better solutions in such situations. Income can be included in utility calculations for a better understanding of problems linked to acceptability. This paper shows how the approach can be used in policy evaluation when income is included in user preferences. With the MATSim framework, the implementation is tested in a simple scenario. Furthermore the approach works in a large-scale, real-world example. On the basis of a hypothetical price and speed increase of public transit, effects on the welfare distribution of the population are discussed. This approach, in contrast with applied economic policy analysis, allows choice modeling and economic evaluation to be realized consistently.
Real-Time Short-Term Traffic Speed Level Forecasting and Uncertainty Quantification Using Layered Kalman Filters
Authors: Guo Jianhua , Williams Billy M.
Published: December 2010

Short-term traffic condition forecasting has long been argued as essential for developing proactive traffic control systems that could alleviate the growing congestion in the United States. In this field, short-term traffic condition level forecasting and short-term traffic condition uncertainty forecasting play an equally important role. Past literature showed that linear stochastic time series models are promising in modeling and hence forecasting traffic condition levels and traffic conditional variance with workable performance. On the basis of this finding, an autoregressive moving average plus generalized autoregressive conditional heteroscedasticity structure was proposed for modeling the station-by-station traffic speed series. An online algorithm based on layered Kalman filter was developed for processing this structure in real time. Empirical results based on real-world station-by-station traffic speed data showed that the proposed online algorithm can generate workable short-term traffic speed level forecasts and associated prediction confidence intervals. Future work is recommended to develop and test a proactive traffic control system in a simulated environment, to refine the uncertainty modeling through a stochastic volatility model, and to extend uncertainty modeling and forecasting to link level and network level.
Defining Interalternative Error Structures for Joint Revealed Preference-Stated Preference Modeling
Authors: Yáñez María Francisca , Cherchi Elisabetta , de Dios Ortúzar Juan
Published: December 2010

Joint model estimation with revealed (RP) and stated preference (SP) data has become popular in the past few years, and it is now considered common practice. Many theoretical issues related to estimation and prediction with joint RP-SP data are far from being fully explored. Given the ample diffusion of RP-SP modeling in practice, its misuse can have severe consequences on policy analysis and evaluation of transport investments; thus, it is crucial to continue research on this problem to try to give a theoretical justification to the many relevant issues that remain uncovered. One particularly interesting issue, which has not been well explored, is the effect of partial data enrichment on the correlation structure of alternatives (i.e., when different correlation structures are revealed in the RP and SP data sets). This problem, which is often found in practice, has no trivial solution and raises new interesting theoretical questions about estimation and prediction. In this paper, theoretical and practical implications of this problem are discussed and then empirical evidence is provided, from a real case, of the errors that may creep in when these models are not applied correctly. Finally some guidelines to help fill this important gap in the proper use of RP-SP data are provided.
Review of Evidence for Temporal Transferability of Mode-Destination Models
Authors: Fox James , Hess Stephane
Published: December 2010

One main motivation for developing travel behavior models is to use them to forecast future levels of transport demand. Given that the interest in transport planning is often in long-term forecasts, with forecast horizons of up to 30 years, it is important to consider the transferability of travel behavior models over time. The importance of model transferability has been recognized since disaggregate models were first applied in the late 1970s and early 1980s, but seems to have been largely forgotten recently, because the focus has been on the development of ever more advanced models that better explain current behavior, with a particular focus on the representation of taste heterogeneity. However, there are sufficient grounds to suspect that the model that best explains current behavior may not necessarily be the best tool for forecasting, not least because of the risk of overfitting to the base data. This paper aims to return the crucial issue of temporal transferability of travel demand models to the research agenda. First, the notion of transferability is discussed, highlighting the potential impacts of violations of the assumption of transferability, and the way transferability can be assessed is also described. Next, the most complete review of existing work investigating the temporal transferability of mode and mode-destination models to date is presented. Finally, a number of areas in which future research should be directed are identified.
Patronage Ramp-Up Analysis Model Using a Heuristic F-Test
Authors: Chang Justin S. , Chung Sung-bong , Jung Kyu-hwa , Kim Ki-min
Published: December 2010

This paper deals with a novel patronage ramp-up analysis model. The ramp-up effect represents the delay in ridership take-up during the first periods of new transport services or facilities. This influence is known as one of the external errors of transport demand forecasts, which degrades the reliability of demand studies and economic appraisal for transport schemes. Traditionally, professional judgment and regression analyses have been used to investigate this effect, but the existing methodologies suffer from the inherent limitations of being biased and arbitrary. In this paper, a heuristic F-test is suggested as an alternative framework. The model proposed is tested with road and rail schemes of South Korea. The case studies illustrate the ability of the model to find the ramp-up parameters involving the duration and the ratio of this effect. Subsequently, a numerical example of cost-benefit analysis including ridership ramp-up is provided. The experiment shows that incorporating the ramp-up effect could provide help for more cautious decision making during the appraisal. A summary and future directions of the study are also provided.
Analysis of Implicit Choice Set Generation Using a Constrained Multinomial Logit Model
Authors: Bierlaire Michel , Hurtubia Ricardo , Flötteröd Gunnar
Published: December 2010

Discrete choice models are defined conditional to the analyst's knowledge of the actual choice set. The common practice for many years has been to assume that individual-based choice sets can be deterministically generated on the basis of the choice context and characteristics of the decision maker. This assumption is not valid or not applicable in many situations, and probabilistic choice set formation procedures must be considered. The constrained multinomial logit model (CMNL) has recently been proposed as a convenient way to deal with this issue, as it is also appropriate for models with a large choice set. In this paper, how well the implicit choice set generation of the CMNL approximates the explicit choice set generation is analyzed as described in earlier research. The results based on synthetic data show that the implicit choice set generation model may be a poor approximation of the explicit model.
Implementation Framework and Development Trajectory of FEATHERS Activity-Based Simulation Platform
Authors: Bellemans Tom , Kochan Bruno , Janssens Davy , Wets Geert , Arentze Theo , Timmermans Harry
Published: December 2010

To facilitate the development of dynamic activity-based models for transport demand, the FEATHERS framework was developed. This framework suggests a four-stage development trajectory for a smooth transition from the four-step models toward static activity-based models in the short term and dynamic activity-based models in the long term. The development stages discussed in this paper range from an initial static activity-based model without traffic assignment to a dynamic activity-based model that incorporates rescheduling, learning effects, and traffic routing. To illustrate the FEATHERS framework, work that has been done on the development of static and dynamic activity-based models for Flanders (Belgium) and the Netherlands is discussed. First, the data collection is presented. Next, the four-stage activity-based model development trajectory is discussed in detail. The paper concludes with the presentation of the modular FEATHERS framework, which discusses the functionalities of the modules and how they accommodate the requirements imposed on the framework by each of the four stages.
Multiple Objectives in Travel Demand Modeling
Authors: Hollander Yaron
Published: December 2010

Traditional techniques for estimating travel demand models cannot always identify a model if the quality of the input data is poor. These techniques do not allow modelers to easily predefine types of travel behaviors that they or their clients believe cannot be true. Models estimated with the best academic practice also may occasionally fail important validation tests. These factors often lead practitioners to determine model parameters through an inefficient trial-and-error process. A multiobjective model estimation procedure is presented that overrules solutions that cannot meet either statistical or political criteria. This procedure is not intended to criticize the traditional modeling approach, but it illustrates that a more pragmatic approach is available and works efficiently. This conclusion is illustrated in the estimation of a demand model for Dublin, Ireland.
From Microsimulation to Nanosimulation
Authors: Duncan Gordon
Published: December 2010

In the past 15 years microsimulation software tools have increased the ability to analyze congested traffic by modeling at the level of individual vehicles. Although this can be very detailed, it assumes that mode choice is fixed. The research presented models the people in the network, either walking or in vehicles, following each person for an entire trip through multiple modes of travel. This approach is called “nanosimulation.” The paper presents a pilot project that analyzes access to an airport by comparing multiple parking options, rail transit, drop-off, and taxi access. Generalized cost incorporating time, distance, and price is visualized for each access method and allows comparison of the total end-to-end cost of all combinations of modes in an interactive three-dimensional simulation model. The primary objective of the research presented is to prove that analysis at this level is practical and can provide insight that is not available from other methods. A historical perspective of microsimulation is presented to illustrate how seemingly impractical models that were run on a supercomputer in 1994 are now in common use on sub-$1,000 everyday computers. The paper describes the technologies, data structure, and algorithms used in the research and addresses the issues of data availability and model repeatability. The model area is described, with illustrations of the visualization. The final sections present results of the project, followed by conclusions and recommendations.
Efficient Methodology for Generating Synthetic Populations with Multiple Control Levels
Authors: Auld Joshua , Mohammadian Abolfazl
Published: December 2010

This paper details a new methodology for controlling attributes on multiple analysis levels in a population synthesis program. The methodology determines how household- and person-level characteristics can jointly be used as controls when populations are synthesized as well as how other multiple-level synthetic populations, such as firm and employee or household and vehicle, can be estimated. The use of multilevel controls is implemented through a new technique involving the estimation of household selection probabilities on the basis of the probability of observing each household, given the required person-level characteristics in each analysis zone. The new procedure is a quick and efficient method for generating synthetic populations that can accurately replicate desired person-level characteristics.
Integrating an Activity-Based Travel Demand Model with Dynamic Traffic Assignment and Emission Models
Authors: Hao Jiang Yang , Hatzopoulou Marianne , Miller Eric J.
Published: December 2010

Microsimulation is becoming more popular in transportation research. This research explores the potential of microsimulation by integrating an existing activity-based travel demand model, TASHA, with a dynamic agent-based traffic simulation model, MATSim. Differences in model precisions from the two models are resolved through a series of data conversions, and the models are able to form an iterative process similar to previous modeling frameworks using TASHA and static assignment using Emme/2. The resulting model is then used for light-duty vehicle emission modeling where the traditional average-speed modeling approach is improved by exploiting agent-based traffic simulation results. This improved method of emission modeling is more sensitive to the effect of congestion, and the linkage between individual vehicles and link emissions is preserved. The results have demonstrated the advantages of the microsimulation approach over conventional methodologies that rely heavily on temporal or spatial aggregation. The framework can be improved by further enhancing the sensitivity of TASHA to travel time.
Integrated Bilevel Model to Explore Interaction between Land Use Allocation and Transportation
Authors: Zhao Liyuan , Peng Zhong-Ren
Published: December 2010

The purpose of this paper is to develop a bilevel integrated dynamic model—a combination of an upper land use allocation model and a lower transportation model—to quantify the interaction between different land use allocation strategies and the transportation system. To manage the dynamic land use change in spatial and temporal dimensions, the upper-level model uses cellular automata to capture the spatial attributes of land use change, whereas the bid–rent agent model focuses on household location choice behavior. The cell-based land allocation strategy and residential location choice generated in the upper-level model are fed into the lower-level model to reflect new transportation demand, travel cost, and transportation accessibility. Then, the travel cost and transportation accessibility produced in the lower-level model are fed back into the upper-level model. To optimize land use allocation strategy, a combination of a genetic algorithm and a Frank–Wolfe algorithm is used to minimize transportation system costs. Numeric analysis of a fictitious urban area showed that the optimal land allocation with the bilevel model significantly enhanced transportation efficiency and reduced the system cost of transportation by 30.8% to 90.2%.
Internet Access
Authors: Smith Colin , Spitz Greg
Published: December 2010

Travel surveys can reach potential survey respondents in many ways, including intercepting them at activity centers or on transit vehicles and contacting them by telephone, mail, or online. The selection of a survey recruitment approach should consider whether the population from which a sample is drawn is fully covered in order to avoid coverage error. This paper presents two case studies that review data collected in travel surveys in metropolitan areas in the United States to identify coverage error, specifically whether lack of Internet access by a segment of the population leads to coverage error. The first case study analyzes data from several road pricing surveys to quantify differences between those who have and do not have Internet access. The second case study analyzes data from two transit origin–destination surveys in which respondents were invited to provide contact details for additional market research. This paper compares the overall sample with those willing to be surveyed in the future by telephone and those willing to receive a future survey invitation by e-mail. Both case studies find that the samples with access to the Internet are similar to the larger full samples that include those without Internet access and therefore that the coverage error found in the Internet-only samples is small. The results suggest that, for surveys of general populations of drivers or transit riders, surveying only those with Internet access does not introduce significant coverage error into travel survey samples.
Estimating Price Elasticities of Ferry Demand
Authors: Adler Thomas , Dehghani Youssef , Gihring Celine
Published: December 2010

Washington State Ferries operates what is by far the largest ferry system in the United States. The ferry routes serve as the primary transportation link to several islands in Puget Sound. Customers include a mixture of commuters, nonwork travelers, and tourists who use the ferries as walk-on or drive-on passengers. The system experiences seasonal and time-of-day peaks that result in some routes operating at capacity for drive-on customers. As part of a recently completed long-range planning effort, Washington State Ferries in association with the state's transportation commission wanted to evaluate the impact of changes in fare policies—in particular, to analyze the effects of charging different fares at different times of day. Fare levels have changed several times over the past several years. The resulting elasticities corresponding to these fare increases were calculated and provide a reasonable foundation for estimating the effects of future fare changes. However, the elasticities do not reflect the effects of charging different fares by time of day. To estimate those elasticities, a stated preference survey was designed and administered to current drive-on customers. Data from the survey were used to estimate both segment-level discrete choice models for choice of alternative drive-on sailings, walk-on, or shifting to an alternative route or mode. Hierarchical Bayes estimation was used to develop models that reflect random heterogeneity in preferences and those models were used in a simulation model to estimate time-of-day fare elasticities. This paper describes the resulting fare elasticities and their implications for fare policy.
Intelligent Transportation System as Evaluation Tool in a Regional Demand Modeling Environment
Authors: Xiao Yan , Hadi Mohammed , Ozen Halit , Mysore Vidya
Published: December 2010

A number of tools have been developed to support the evaluation of intelligent transportation system (ITS) alternatives. However, the methodologies and some associated parameters in these tools were developed and selected before widespread deployments of ITSs. Significant experience gained with ITS in recent years warrants a new assessment of the evaluation methodologies and parameters of these systems. There are also advantages to incorporating the evaluation of ITS deployments as part of existing regional demand forecasting modeling environments rather than using external tools to perform this functionality. This paper discusses the development and implementation of a tool and methodologies to estimate the benefits and costs of these systems as part of a travel demand forecasting modeling environment. It also presents an application of the developed tool to evaluate two of the most widely deployed types of ITS: incident management and advanced traveler information systems. Case study results indicate that the methodologies developed in this study can be used to assess ITS deployments.
Applying Benefit–Cost Analysis for Airport Improvements
Authors: Landau Steven , Weisbrod Glen , Alstadt Brian
Published: December 2010

Benefit–cost analysis (BCA) is widely used for airport investment analysis, for both ranking of alternatives and funding decisions. Although the technique is theoretically straightforward, its application can become complicated by a series of factors that are particularly problematic for aviation applications. For one, the requirement for ground access makes air travel intrinsically multimodal. In addition, the speed of air travel attracts classes of users and dependent parties with particular speed sensitivities and delay consequences. When BCA is applied to airport project proposals, it can raise issues of how to handle competing modes and intermodal interactions, and the definition of the real users and beneficiaries of airport improvements. To examine these issues, the authors compared benefit–cost guidance for airports with counterpart guidance for other travel modes and conducted a review of the current state of practice of benefit–cost studies for airport improvements. The findings point to challenges for improving methods of airport BCA.
Impact of Airport Noise on Property Values
Authors: Chalermpong Saksith
Published: December 2010

The impact of airport noise on home prices has received much attention in North America, where many hedonic price studies have been performed to examine the issue. In developing countries, however, extremely limited academic work on this topic has been conducted. The recent opening of Suvarnabhumi Airport in Bangkok, Thailand, presented a unique opportunity to address this research gap. In this paper, sales data of new homes near the airport that were sold between 2002 and 2008 are used to examine both the anticipatory effect and actual effects of airport noise on home prices. On the basis of this data set, hedonic price models are estimated and subjected to various diagnostic tests, including those for heteroscedasticity and spatial autocorrelation. The results show no anticipatory effects of airport noise on prices before the beginning of airport operations in 2006. More important, prices of new properties sold after 2006 are 19.15% lower in the most severely affected area and 8.55% lower in moderately affected areas. These estimates imply a noise depreciation index of 2.12% per decibel, which is in the high range of values found in the literature and implies that the potential benefits of a noise reduction program at Suvarnabhumi Airport might be substantial.
Mitigation of Aviation Emissions of Carbon Dioxide
Authors: Dray Lynnette , Evans Antony , Reynolds Tom , Schäfer Andreas
Published: December 2010

This paper investigates the interaction between economic, technological, and operational measures intended to reduce air transport-related emissions of carbon dioxide (CO2). In particular, the introduction of aviation to the European Union Emissions Trading Scheme (ETS) in 2012 may prompt increased uptake of presently available options for emission reduction (e.g., retrofitting winglets, expanding maintenance programs) by airlines operating in Europe. Carbon prices may also determine the use of options currently under development [e.g., open-rotor engines, second-generation biofuels, and improved air traffic management (ATM)]. The results of a several studies analyzing airline costs and emission reductions that are possible from different mitigation options are applied to a systems model of European aviation. With a set of nine scenarios (three internally consistent projections for future population, gross domestic product, oil and carbon prices, each run with three policy cases), technology uptake and the resulting effect on fuel life cycle CO2 emissions with and without an ETS are analyzed. Some options are rapidly taken up under all scenarios (e.g., improved ATM), others are taken up more slowly by specific aircraft classes depending on the scenario (e.g., biofuels), and others have negligible impact in the cases studied. High uptake of one mitigation option may also reduce the uptake of other options. European aviation fuel life cycle emissions could be reduced below 2005 levels before 2050 if cellulosic biomass fuels are made available by 2020. However, the land use requirements in this scenario may limit its practicality at currently projected cellulosic biomass yields.
Aircraft Traffic Analysis for Forecasting
Authors: Cripwell J. Paul
Published: December 2010

Analysis of historical air traffic is used to determine trends that will assist in traffic forecasting. This process begins with externally supplied forecasts that use econometrics as a base to produce passengers and movements as an output, which is then refined through the results of traffic analysis. The paper begins by defining the service charge structure for Nav Canada and defines two main service charges, one related to departures from Canadian airports and one related to the distance traveled by these flights. From the defined markets, domestic, transborder, south, Atlantic, and Pacific monthly growth rates are examined for potential trends. Although frequency may be a primary driver underlying much of the growth, the service charge structure includes the components of aircraft size (weight) and distance, factors that are not included in external forecasts. The paper presents the growth rates of all three components (frequency, aircraft size, and distance) within these markets to identify potential areas for further analysis and then examines the domestic market in more detail to determine the causes of traffic changes and their impact on a forecast on a month-by-month basis. This analysis also reveals further questions and identifies the need for additional analytical techniques.
Validation of Runway Capacity Models
Authors: Kim Amy , Hansen Mark
Published: December 2010

Many runway capacity estimation models are available today, and developers usually claim that their models have been validated. However, information about the validation process is often limited, and different models are validated at differing levels of complexity. This paper proposes two validation methodologies for use in testing model predictions against reality. It demonstrates the two methodologies on two models [the airfield capacity model (ACM) and the runway simulator (rS)] and two airports (San Francisco International and Los Angeles International in California). The results indicate that when arrivals and departures are considered separately, both ACM and rS tend to overpredict capacities under good visibility conditions and to predict larger ranges of capacity values than are seen empirically. However, when considering total operations (arrivals and departures together), the results show that both models failed to provide good estimates of total throughput at both airports. Overall, arrival and departure capacity estimates from rS typically reflect empirical capacities better than those from ACM.
Statistical Characteristics of Aircraft Arrival Tracks
Authors: Shortle John F. , Zhang Yimin , Wang Juan
Published: December 2010

The statistical characterization of flight tracks is a critical component of safety analysis models. This paper presents an analysis of multilateration data that uses an extension of an algorithm. Key results are as follows: the separation distribution does not appear to change much at different points along the approach path. The left tail of separation (corresponding to the smallest separation values) decays faster than a normal distribution. This is positive from a safety perspective. If this behavior is extrapolated beyond the observed data, one can conjecture that smaller separations have probabilities that rapidly decay to effectively zero. Lateral positions near the threshold do not appear to be heavy tailed, either. Finally, estimates of the final approach separation variability are consistent with previously published results.
Incorporating Risk of Failure into Maintenance Management of Cracks in Runway Pavements
Authors: Pasindu H. R. , Fwa T. F.
Published: December 2010

To ensure safe runway operations and make the best use of maintenance funds, cracks in runway pavements should be repaired according to severity and maintenance needs. In traditional pavement maintenance management, priority of crack repair is determined by crack width, length, density, extent, and sometimes location. However, this basis for prioritization is not entirely satisfactory because it does not consider aircraft operational characteristics and may not assign priority correctly. One possible improvement is to apply the concept of failure risk in analyzing runway pavement cracks and to assign higher priority to cracks with higher risk of failure or interference with safe aircraft operations. This paper illustrates how this concept can be incorporated into maintenance management of cracks in runway pavements by employing structural analysis that uses a mechanistic approach. In addition to the dimensions and characteristics of cracks mentioned earlier, crack depth, aircraft loading, and operational characteristics have to be considered. In the analysis of failure risk, the proposed methodology considers frequency of different aircraft types and statistical distributions of their wheel loadings during landings and takeoffs, touchdown points, and lateral wanders. For each crack with known dimensions and location, the stresses and strains under load are computed by using finite element analysis. The crack's failure risk is expressed by means of Miner's rule, which in turn forms the basis for maintenance prioritization. The detailed steps of the proposed methodology are described in this paper, and a numerical example is presented to demonstrate the application of the methodology.
Performance of New Materials for Aircraft Arrestor Beds
Authors: Santagata Ezio , Bassani Marco , Sacchi Emanuele
Published: December 2010

The design and the construction of currently employed aircraft arrestor beds require the presence of soft ground in which an aircraft in overrun decelerates as a result of drag forces acting on its landing gear. During this interaction, the wheels crush or displace the material until the airplane is completely stopped. The arresting systems are of special importance for those airports that do not have a safety area of the length required by international regulations. In the recent past, several materials with the capability for high energy absorption have been proposed, but most of them have been rejected so that some secondary effects—such as dust production during overrun, which leads to engine failure; short durability to environmental conditions; and limited mobility for rescue vehicles—can be reduced. This paper describes an experimental investigation performed on new materials by employing innovative testing protocols. Four materials of low density and low compressive strength—such as cellular mortar, cellular mortar with expanded polystyrene, and expanded clay pellets with bitumen and cement binder—have been considered. Quasi-static tests have been performed to define elastic–plastic transition points, and impact tests have been considered to assess the amount of energy that can be absorbed under the gears during the collapsing phase. Performance indicators of these new materials have been highlighted and compared with traditional indexes normally used for the characterization of existing arrestor beds.
Impact of Congestion on Taxi Times, Fuel Burn, and Emissions at Major Airports
Authors: Simaiakis Ioannis , Balakrishnan Hamsa
Published: December 2010

Taxiing aircraft contribute significantly to fuel burn and emissions at airports. This paper provides a comprehensive assessment of the impact of surface congestion on taxi times, fuel burn, and emissions through analysis of the departing traffic data from four major U.S. airports. Several metrics based on airport throughput and taxi-out times are introduced and studied, including one that considers the number of flights that encounter a congested airport, a second metric that compares the observed taxi-out times with the unimpeded ones, and a third that evaluates them in conjunction with the airport throughput.
Quantifying Metrics of External Airport Risk Exposure in Vicinity of Public Use, Nontowered Airports
Authors: Salmon Christian M. , Motevalli Vahid , Harrald John , Van Dorp Johan René
Published: December 2010

This paper presents research conducted in modeling specific exposure metrics of communities in the vicinity of public use, nontowered airports to aviation accidents that result in crash sites outside the immediate confines of a runway (termed external airport risk). Two exposure metrics are explored: a relative exposure (termed crash hazard), defined as the probability that a crash site will be located in a specific area if a crash were to occur at an airport, and an absolute exposure (termed crash risk), defined as the expected number of crashes per year within any defined area. Results of this research are presented as a series of choro-pleth maps that define boundaries as contours, within which these metrics exceed some defined threshold. A specific application of this research is presented within the context of a model airport.
Exploring the Pilot Reliability Certification Program and Changing Attitudes on Reducing Pilot Errors
Authors: Boedigheimer Dan
Published: December 2010

The greatest opportunity to improve aviation safety is to focus on reducing human errors in the cockpit. This research evaluated whether there was knowledge gain and difference in attitudes toward reducing human error in the cockpit after implementation of the Pilot Reliability Certification (PRC) program at Federal Aviation Regulation (FAR) 135 air carriers and FAR 91 corporate flight departments. The program is a human factors training curriculum focused on personal vulnerabilities to human error and countermeasures in support of aviation safety. Three levels of measurement were used: reactions to training, a knowledge test, and a modified version of the cockpit management attitudes questionnaire to assess attitude change. A mixed-method approach was used with quantitative data to measure knowledge gain and attitude change along with qualitative data to explore pilot reactions to the training. A quasi-experimental group (n = 41) that completed the 2-day course was compared with a control group (n = 62). The control group showed no significant improvement in attitude related to crew resource management skills or the PRC objectives. The quasi-experimental group had significantly improved attitudes and knowledge gain. Reaction to training was positive, with pilots citing a strengthened human factors knowledge base as the greatest benefit. They thought that the training differed from previous human factors training by being more detailed and in depth. After taking the course, pilots said that they would be more conscious of evaluating themselves, their flying partners, and their attitudes.
Washington State Department of Transportation Plan for Accelerated Bridge Construction
Authors: Khaleghi Bijan
Published: December 2010

The need for accelerated bridge construction (ABC) arises from the increases in traffic congestion over the past few decades and the corresponding costs and safety issues manifest in many forms, including exposure of workers to traffic hazards and waste of time caused by delays. Prefabricated bridge components are in increasing demand for ABC. Precasting eliminates the need to form, cast, and cure concrete in the work zones, making bridge construction safer and improving quality and durability. Precast bridges consisting of pretensioned girders, post-tensioned spliced girders, trapezoidal open-box girders, and other types of superstructure members are often used for ABC; however, bridge engineers are concerned about the durability and performance of bridges made of precast members in areas of high and moderate seismicity. Starting in 2008, the Washington State Department of Transportation (DOT) initiated a practice development and implementation for ABC. Washington State DOT has established a task force headed by an ABC advisory committee to develop standards, guidelines, and key policies for implementing structure design for ABC.
One-Weekend Job
Authors: Ardani Ahmad A. , (Shana) Lindsey Rukhsana , Mallela Jagannath
Published: December 2010

As part of a national initiative sponsored by FHWA under the Highways for LIFE program, the Utah Department of Transportation (DOT) was awarded a $1 million grant to demonstrate the use of proven, innovative technologies for accelerated bridge removal and replacement. This report documents accelerated bridge construction (ABC) techniques used to remove and replace the 4500 South Bridge on State Route 266 over Interstate 215 in Salt Lake City during a weekend. It includes construction details of the bridge superstructure built offsite on temporary abutments and prefabricated and cast-in-place bridge components and substructure built under the existing bridge without interfering with traffic flow. It also discusses use of a self-propelled modular transporter (SPMT) to remove the old bridge and to replace it with a new one. With conventional construction, the impact of this project on the traveling public was estimated at 120 days, but with accelerated construction techniques the impact was reduced to a single weekend for I-215 and 10 days for State Route 266. Using an SPMT and other ABC techniques added about $0.81 million to the initial construction cost of the project. However, a more comprehensive economic analysis including user cost savings shows that the project saved road users about $3.24 million (or about 36% of the total project costs). Because of the success of this project, the Utah DOT has decided to use ABC techniques more routinely in future projects and has set a goal of making ABC standard practice for all bridges by 2010.
Induced Stresses from Lifting and Moving Highway Bridges with Self-Propelled Modular Transporters
Authors: Rosvall Erik S. , Halling Marvin W. , Lindsey Rukhsana
Published: December 2010

This study discusses five bridges on I-80 in Utah that were replaced in the summer of 2008 by using accelerated bridge construction methods. Each superstructure was built off site and moved into place with self-propelled modular transporters. The bridges were instrumented and monitored during the moving process to investigate the effects of moving an entire superstructure into place. Collected data were analyzed to find the level of stress each superstructure experienced during lifting, moving, and placement of each bridge. Support conditions for these bridges changed considerably. During construction and when permanently placed, they were simply supported structures. During transport, the lift points were in the interior of the bridges, resulting in cantilevered ends and considerable stress reversals in the entire bridge. A two-dimensional analysis was done using the dead load of the structure to find the initial stresses in the superstructure when supported on temporary abutments. The measured change in stress resulting from lifting was compared with calculations. The difference between the two stresses was defined as the lifting stress in the superstructure. Dynamic stresses incurred as a result of bridge movement are determined and compared with recommendations.