bluuebunny/crossref_metadata_2025 huggingface dataset:
Outcomes after Endoscopic Dacryocystorhinostomy without Mucosal Flap Preservation
Authors: Ramakrishnan Vijay R. , Hink Eric M. , Durairaj Vikram D. , Kingdom Todd T.
Published: January 2008

Background

The purpose of this study was to evaluate outcomes of powered endoscopic dacryocystorhinostomy (DCR) without the preservation of mucosal flaps for the management of acquired nasolacrimal duct obstruction.

Methods

A retrospective review was performed of patients undergoing endoscopic DCR without mucosal flap preservation from May 2003 to October 2006 at a tertiary referral medical center. Twenty-seven procedures were performed on 20 patients with epiphora secondary to acquired nasolacrimal duct obstruction. Main outcome measures were subjective improvement in epiphora and assessment of anatomic patency based on lacrimal irrigation.

Results

Mean follow-up was 16 months. Mild intermittent postoperative epiphora or complete resolution of epiphora was noted in 100% (27/27) of procedures; complete resolution was recorded in 93% (25/27) of procedures. Eighteen patients (25 procedures) were available for lacrimal irrigation at a mean of 16 months follow-up. Anatomic patency was confirmed in 100% (25/25) of procedures.

Conclusion

Our results with endoscopic DCR are comparable with previously published outcomes. These data suggest that successfully powered DCR may be performed without the preservation of mucosal flaps.
Staphylococcal Enterotoxins A and B Enhance Rhinovirus Replication in A549 Cells
Authors: Wang Jong Hwan , Kwon Hyun-Ja , Lee Bong-Jae , Jang Yong Ju
Published: January 2008

Background

Staphylococcal enterotoxin A (SEA) and staphylococcal enterotoxin B (SEB) have been reported to be important in the pathogenesis of chronic rhinosinusitis (CRS). To elucidate the pathophysiological responses in the nasal mucosae of CRS patients associated with rhinovirus (RV) infection, we investigated the effects of SEA and SEB on RV infection in A549 cells.

Methods

Changes in expression of intercellular adhesion molecule (ICAM) 1 were assessed by flow cytometry, and effects on cytokine secretion were measured by ELISA. The changes of ICAM-1, IL-1beta, IL-6, and IL-8 mRNA were assayed by real-time polymerase chain reaction. The effect of RV replication in the cells was assessed by viral culture, followed by determination of viral titer.

Results

RV infection increased ICAM-1 expression and cytokine secretion, but the SEs did not further increase the RV-induced expression of ICAM-1, IL-1beta, IL-6, and IL-8 mRNA and protein. The SEs, however, induced dose-dependent increases in viral titer.

Conclusion

SEA and SEB enhanced rhinoviral replication in airway epithelial cells, indicating that airway epithelial cells with CRS are more favorable environments for RV infection.
The Usefulness of Computed Tomography Scans in Cystic Fibrosis Patients with Chronic Sinusitis
Authors: McMurphy Andrea Barber , Morriss Craig , Roberts Dianna B. , Friedman Ellen M.
Published: January 2008

Background

This study was performed to evaluate the usefulness of computed tomography (CT) scans of the sinuses in children with cystic fibrosis (CF) as an outcomes measurement for medical and surgically treated chronic rhinosinusitis.

Methods

Patients with CF who had sinus scans performed at the study institution from January 1999 to September 2003 were identified. The scans and any available prior scans were scored according to the Lund-MacKay system. A retrospective chart review determined if hospitalization with i.v. antibiotic therapy or operative intervention had occurred between scans and if the scans showed improvement secondary to the intervention.

Results

One hundred thirty-four patients were identified who met inclusion criteria. A total of 290 scans were reviewed, with the average number of CT scans per patient of 2.24 (range, 1–10). The average Lund-MacKay score for scans closest in time to the first sinus surgery was 14.5. (range, 7–24), and for the first postoperative scans, the score was 14.7 (8–24). There was no significant difference between the preoperative and postoperative Lund-MacKay score after initial surgery (p = 0.99) or in subsequent scans despite medical or surgical interventions (p = 0.90).

Conclusion

CT scanning of the sinuses does not appear to be useful in determining outcomes of intervention in CF patients.
Long-Term Outcome Analysis of Endoscopic Sinus Surgery for Chronic Sinusitis
Authors: Young Jonathan , Frenkiel Saul , Tewfik Marc A. , Mouadeb Debbie A.
Published: January 2008

Background

The purpose of this study was to determine long-term subjective outcome of endoscopic sinus surgery (ESS) for chronic sinusitis (CS) and to evaluate prognostic indicators for surgical treatment failure.

Methods

This is a prospective study of patients who underwent ESS for CS. Symptom assessment was performed using a visual analog scale at a pretreatment interview and then at regular intervals post-ESS for up to a 3-year period. The indicators for symptom scoring were nasal obstruction, facial pain, postnasal drip, anterior discharge, and anosmia/hyposmia.

Results

Data analysis indicates that ESS improves symptom scoring early on, but the effects begin to dissipate over time. Anosmia/ hyposmia is the most severe symptom overall for all patient subgroups and recurs to a greater degree 3 years postoperatively in Samter's Triad sufferers (p = 0.006), asthmatic patients (p = 0.002), and those with a worse CT scan at presentation (p = 0.04). In addition, Triad sufferers who complain of nasal obstruction and anterior nasal discharge have a significant recurrence of their symptoms postoperatively (p = 0.04 and 0.001, respectively).

Conclusion

Individuals must be warned that ESS may not be a long-term solution for CS because of its chronic nature. Patients are relieved of their symptoms initially; however, these tend to recur over a 3-year period. Samter's Triad is the strongest determinant of long-term treatment failure. Asthma also is a determinant of treatment failure, which lends credence to the notion of combined airway disease. Allergy was not a strong determinant of treatment failure in our study.
The Effect of Female Hormone Manipulation on Nasal Physiology
Authors: Robinson Anne M. , Philpott Carl M. , Gaskin Julian A. , Wolstenholme Charlotte R. , Murty George E.
Published: January 2008

Background

This study was performed to establish whether the ovarian hormone beta-estradiol has any influence on nasal physiology when manipulated during in vitro fertilization treatment.

Methods

Women undergoing in vitro fertilization (IVF) treatment at the Assisted Conception Unit, Leicester Royal Infirmary, were recruited. Nasal peak inspiratory flow rate, acoustic rhinometry, anterior rhinomanometry, mucociliary clearance, olfactory thresholds, quality of life, and serum 17-beta-estradiol levels were measured at each visit. Subjects were studied at the beginning of their IVF treatment and then at one or two additional occasions while they received synthetic follicule-stimulating hormone with a final set of results taken at the end of their treatment.

Results

Results were analyzed using paired t-tests. There was no statistical difference between any of the data sets for any of the variables during the process of IVF treatment.

Conclusion

Increasing levels of beta-estradiol that occur in IVF treatment cause no significant effect on nasal physiology in contrast to the effects seen during pregnancy.
NAFTA's Shadow Hangs Over Kyoto's Implementation
Authors: Hornsby David J. , Summerlee Alastair J.S. , Woodside Kenneth B.
Published: January 2008

The Canadian government indicated recently that it will not meet its Kyoto targets but will develop a "made in Canada" solution to deal with the reduction of climate-changing greenhouse gas emissions. Canada is still legally obligated to achieve its Kyoto reduction requirements and has indicated that it will participate in the second round of Kyoto Protocol talks. However, as a co-signatory of the North American Free Trade Agreement (NAFTA), Canada may be impeded from introducing and maintaining greenhouse gas-reducing initiatives as there are elements of NAFTA which may be used to challenge or block efforts that are considered discriminatory to trade. In particular, Chapter 11 may be used as a vessel by private investors to challenge climate change measures that conflict with other NAFTA chapters. Unless these conflicts are addressed, the Canadian government will fail in its initiatives.
The Mythical Frontier, the Mexican Revolution, and the Press: An Imperial Subplot
Authors: Cronlund Anderson Mark
Published: January 2008

Abstract:

The frontier myth has served as America's secular creation story. As a result, it surfaces widely in popular culture and political discourse. It also resonates in news coverage. This paper explores how the American press framed the Mexican Revolution as a mythical frontier narrative by examining depictions of revolutionary Francisco “Pancho” Villa. The news story that emerges bears close resemblance to the frontier thesis, as articulated by historian Frederick Jackson Turner.
“Jesus, My Pal”: Reading and Religion in Middlebrow America
Authors: Smith Erin A.
Published: January 2008

Abstract:

Bruce Barton was an advertising executive and the author of a best-selling life of Christ, The Man Nobody Knows (1925). Although they were immensely popular, Barton's books are dismissed by scholars today as theologically empty justifications for consumer capitalism. Through an analysis of letters from readers, this essay argues that Barton's work was part of the “lived religion” of ordinary Christians, whatever its intellectual or theological failings. First, it filled a vacuum in advice in modern America. Second, it finessed the impersonal scale of urban life by presenting Jesus as a friend. Third, it rendered irrelevant deeply felt contradictions in Protestant America between religion and science, fundamentalism and modernism. I demonstrate a gap between intellectuals and ordinary readers that has implications for our own scholarly practices.
Conjuring Trauma: The Naudet Brothers' 9/11 Documentary
Authors: Craps Stef
Published: January 2008

Abstract:

The events of 11 September 2001 caused a rupture not only in the normal order of things but also, and perhaps especially, in the signifying systems underwriting that order. The Naudet brothers’ remarkable 9/11 documentary, which aired on CBS on 10 March 2002 and on TV stations around the world on the first anniversary of the attacks, seeks to reinstitute the authority of the conventions and constructions of a culture whose limits the events of 11 September had painfully exposed. The film—entitled 9/11—is marked by a fundamental tension between the revelation of an abysmal crisis of meaning, on the one hand, and the desire to bring this crisis under control, on the other. The filmmakers attempt to mitigate the traumatic potential of their unique atrocity footage by sanitizing it and integrating it into a Hollywood-style coming-of-age drama tracing a probationary fire-fighter's perilous journey from innocence to experience. Thus, the focus shifts from a disorienting and overwhelming sense of loss to comforting, ideologically charged notions of heroism and community that perpetuate an idealized national self-image and come to function as a moral justification for retaliation. In its drive to obtain mastery over trauma by rendering it legible in terms of existing cultural codes, 9/11 appears to disregard what Cathy Caruth calls “the event's essential incomprehensibility, the force of its affront to understanding” (154). Yet, for all its investment in a classical realist aesthetic, the film remains haunted by a traumatic history that exceeds and breaks down accustomed habits of thought, narration, and visualization.
Internal Colonization and the Culture of Street Life in Bud Osborn's hundred block rock
Authors: Campbell Kofi
Published: January 2008

Abstract:

This paper discusses Bud Osborn's poetry collection, hundred block rock, which focuses on the lives of the homeless and disenfranchised in North America. It suggests that postcolonial theories can be fruitfully applied to the study of the North American homeless and indigent population, thereby shedding light on some of the processes through which that population is both constructed by and attempts to redefine its relationship with the hegemonic order that relegates it to a marginal position. Through a discussion of theories of internal colonization, this paper suggests that that term is more correctly applied to the world of the homeless and disenfranchised than to the groups it normally is used to describe. Through an engagement with theories of diaspora, the paper attempts to revise our understanding of this world.
New Predictive Models for Viscosity and Complex Shear Modulus of Asphalt Binders
Authors: Bari Javed , Witczak Matthew W.
Published: January 2008

The main purpose of this paper is to present the development of a set of predictive models for the viscosity and complex shear modulus of asphalt binders. The model development was aimed at overcoming the limitations of current models used in the Mechanistic-Empirical Pavement Design Guide (MEPDG), which has been developed under NCHRP Project 1-37A and refined under NCHRP Project 1-40D. A comprehensive study was completed at Arizona State University to conduct a number of asphalt binder tests and to finalize a large binder characterization database containing 8,940 data points from 41 different virgin and modified binders. This database was used to develop the new models. The first of the models developed in this study is a fully revised version of the widely known ASTM Ai-VTSi viscosity model. This new, revised model takes into account the loading frequency applied on the binder while accurately predicting the viscosity at a specific temperature and loading frequency from the Ai and VTSi values of a binder. The other two new models developed are capable of accurately predicting the dynamic shear modulus (|G*b|) and associated phase angle (δb) of the binder at a specific temperature and loading frequency from the Ai and VTSi values of the binder. The models have been found to be rational, unbiased, accurate, and statistically sound. It is hypothesized that because of mathematical structures similar to those used in the MEPDG, the models developed in this study can be incorporated easily into a future revision of the guide.
Surface Free Energy to Identify Moisture Sensitivity of Materials for Asphalt Mixes
Authors: Bhasin Amit , Little Dallas N. , Vasconcelos Kamilla L. , Masad Eyad
Published: January 2008

Conventional methods to quantify the moisture sensitivity of asphalt mixtures are based on the comparison of mechanical properties of the mix before and after a moisture-conditioning process. Although this approach consolidates the effect of material and mixture properties on moisture sensitivity, it does not identify the causes responsible for the poor or good performance of the mixture. In this study, surface free energy of asphalt binders and aggregates was used to derive energy parameters that quantify the moisture sensitivity of various combinations of materials. The moisture sensitivity of 12 asphalt mixtures carefully designed to represent a wide range of asphalt-aggregate interactions was measured in the laboratory under controlled conditions. Test results indicate that the moisture sensitivity of these mixtures correlates well with the energy parameters, which are based on the surface energy properties of the constituent materials. Incorporating the specific surface area of the aggregate into the energy parameters improved this correlation. The proposed energy parameters have the potential to serve as an effective tool by which to select material combinations that result in asphalt mixtures that are more resistant to moisture-induced damage.
Optimum Number of Superpave Gyrations Based on Project Requirements
Authors: Aguiar-Moya José P. , Prozzi Jorge A. , Tahmoressi Maghsoud
Published: January 2008

The Superpave® mix design method was developed as part of the SHRP Asphalt Research Program, which extended from 1987 to 1993. The concept behind the Superpave method was that of incorporating performance, environmental conditions, load factors, and material characterization into one design and evaluation process to improve the performance of the asphalt mixtures by reducing rutting, thermal cracking, and fatigue cracking. Several years have passed since the first Superpave mixtures were laid down in numerous states, including Texas. With the introduction in the design process of rolling wheel testers, such as the Hamburg wheel tracking device (HWTD), it has often been observed that although the mixtures perform well with regard to rutting resistance, some pavement sections begin to crack relatively early. One possible reason for this occurrence is that the Superpave volumetric mix design method (Level 1) and the performance requirements for tests such as the HWTD promote asphalt mixtures with relatively low asphalt contents. The mixtures have superior rutting resistance but often sacrifice cracking performance. One way to increase the cracking resistance of Superpave asphalt mixes is to reduce the number of design gyrations (Ndesign) currently used in the Superpave gyratory compactor. This paper introduces a simple method for selecting an optimum number of gyrations based on the performance requirements of the specific project with regard to simultaneous rutting and fatigue. The objective is to produce asphalt mixes that are more resistant to fatigue cracking without compromising their already established superior rutting performance.
Examining Deficiencies in Florida Pedestrian Crash Data
Authors: Wootton Isaac A. , Spainhour Lisa K.
Published: January 2008

In Florida, the Department of Highway Safety and Motor Vehicles serves as the repository for state traffic crash data collected by law enforcement officers. These state data, which are collected on traffic crash reports, limit the type and the extent of the analysis that can be performed because of constraints and errors in the data. Florida state databases lack information from crash narratives and diagrams, which are not mined for data. In addition, crash report data are shown to contain errors. An analysis was initiated to investigate data from 318 fatal crashes involving pedestrians in which detailed traffic homicide reports and other data sources were consulted. The integrity of the state-maintained data for their accuracy and completeness was investigated. Alcohol usage, fault, speed limits, vehicle speeds, and citations were the leading data fields with errors. In the case of pedestrian alcohol test results, state database records were found to be in error more than half the time. Emphasis is given to the methods that can be used to create a quality crash data set and to highlighting the additional insights that can be gained from the homicide reports and other resources, especially for the accurate determination of fault and crash causation.
Methods to Prioritize Pedestrian High-Crash Locations and Statistical Analysis of Their Relationships
Authors: Vasudevan Vinod , Pulugurtha Srinivas S. , Nambisan Shashi S.
Published: January 2008

This paper presents a summary of various methods that can be used to identify pedestrian high-crash locations (HCLs) and statistical evaluations of the relationship between the ranking methods. The indices and methods used to identify and rank pedestrian HCLs include individual methods such as crash indices based on frequency, weighted severity factor, vehicular traffic volume, and pedestrian age group, as well as composite methods such as the sum-of-the-ranks method and the crash score method. The ranks for individual HCLs obtained by these methods may vary, as they are based on different data. There is thus a need to evaluate the statistical relationships between the results obtained by the various methods. Data for 30 pedestrian HCLs in the Las Vegas, Nevada, metropolitan area were used to illustrate the methods and conduct statistical analyses. The results indicated that the rankings based on the individual methods were strongly correlated to the rankings from the composite methods, as were the rankings between the composite methods. The results also indicated that the rankings based on individual methods were correlated among themselves, although this correlation was not as strong. Furthermore, when only the top few highest-ranked HCLs were considered, their ranks were strongly correlated, regardless of the method chosen. Although any of the methods could be used to identify pedestrian HCLs, use of the simple frequency- or weighted frequency-based methods would be adequate as a first step.
Assessing Passenger Comfort and Capacity Bottlenecks in Dutch Train Stations
Authors: Hoogendoorn Serge P. , Daamen Winnie , de Boer Arwina , Vaatstra Ilka
Published: January 2008

The performance indicator of transfer station crowdedness is one of the indicators that offers insight into the performance of the pedestrian transfer station infrastructure and the effects of adjustments (of the infrastructure, traffic demand, or the timetable) on this performance. Because the original method did not provide the expected results, this paper proposes improvements to the means of measuring and assessing this performance indicator on the basis of the levels of service defined by Fruin, complemented by the dimensions of time and frequency. The measurement plan stipulates that densities are used as the main indicator and that they can be collected by using either video or infrared sensors at a frequency of 0.1 Hz for an effective area of at least 10 m2. The modified assessment method entails the identification of Levels of Service D (comfort bottleneck) and E (capacity bottleneck) only when they last longer than 30 s. Actual bottlenecks are indicated only when these levels of service occur more than three times during a peak period and last (in sum) longer than 5 min per peak period. Further improvements to the assessment methodology relate to the use of the effective walking area, including the shy-away distances between pedestrians and obstacles, walls, and so on, rather than the observed area. Also, flow directions appear to have a considerable influence on the level of service. The paper shows the results obtained by application of the methodology to one of the measurement locations.
Model for Estimating Crossing Times at High-Occupancy Crosswalks
Authors: Golani Anais , Damti Harel
Published: January 2008

This paper proposes a model for the estimation of crossing times. The model includes all elements that comprise the crossing time of a pedestrian platoon [start-up time, walking speed, and pedestrian headways (lag)] as a function of the size of the dominant platoon and the opposite platoon separately. The model describes the behavior of groups of pedestrians and not individuals. The proposed model is an adaptation of existing models and is calibrated according to data extracted from a video survey of crosswalks in three major metropolitan areas in Israel. This work was sponsored by the Tel Aviv Metropolitan Mass Transit System, the government company responsible for developing a mass transit system in metropolitan Tel Aviv under the mandate of the Israeli Ministry of Transport. The project developed level-of-service measures for crosswalks and applied it to the planned crosswalks in the vicinity of proposed light rail stations. One of the criteria for these measures is the ratio between the duration of time allotted for the pedestrian movements (pedestrian green light) and the time required for the pedestrian platoon to cross the street. The model described in this paper allows the calculation of that ratio.
Ultrathin Bonded Wearing Course as Pavement Preservation Treatment for Jointed Concrete Pavements
Authors: Corley-Lay Judith B. , Mastin Jeffery Neil
Published: January 2008

Use of an ultrathin bonded wearing course (UTBWC) is reported on as a pavement preservation strategy for jointed plain concrete pavements. This strategy has been used in North Carolina on both urban and rural sections. One of the benefits of the UTBWC is that the elevation change is small, typically 5/8 in. Expenses associated with thick overlays—such as adjustments to signs, guardrails, bridge clearances, and shoulders—are minimized. The effectiveness of the UTBWC in improving ride quality and extending pavement life is evaluated for five projects. North Carolina performs pavement condition surveys every year on the Interstate system and every other year on other systems. On jointed concrete pavements, a sample of 39 to 41 slabs is used for the first 0.1 mi of each mile. Asphalt-surfaced roadways are evaluated by using 100% coverage in a windshield survey. Application of the ultrathin bonded overlays resulted in a dramatic bump in the pavement condition ratings (PCRs). The rate of decline of the PCR after resurfacing with UTBWC is between 0.8 and 3.0 points per year on the basis of two sites. Most decline in PCR to date is associated with reflection cracking, which appears but does not degrade rapidly. Faulting ultimately results in decreased ride quality over time as indicated by increases in international roughness index (IRI). The rate of increase in IRI ranged from 0.5 to 2.1 points per year. On the basis of North Carolina's experience with UTBWC on poor-quality jointed portland cement concrete, a life of 6 to 10 years is attainable and is supported by the projections of performance curves from two of the sites.
Stripping Detection in Asphalt Pavements with Seismic Methods
Authors: Celaya Manuel , Nazarian Soheil
Published: January 2008

Stripping of hot-mix asphalt pavements has been a significant problem for many transportation agencies. The detection of stripping has been carried out by using either visual observation or laboratory strength tests of cores retrieved from the field. Ground-penetrating radar also has been used for this purpose. Seismic methods are presented here as a nondestructive tool to detect the extent of stripping. Seismic tests are beneficial because they are rapid to perform and nondestructive and because the material is tested in its natural state. The portable seismic property analyzer (PSPA) is an example of a device that uses two methods of analysis to detect stripping: ultrasonic surface wave (USW) and impact echo (IE). PSPA results and field cores retrieved (ground-truth data) from two sites were compared. PSPA, with the standard receiver spacing of 6 in., correlated well with cores when they were located in the first 10 in. of the asphalt layer (shallow). For deeper stripping, longer spacing between the receivers should be used. From the two methods of analysis, the USW method was found to be more effective than the IE in visualizing the extent and depth of low-quality layers in terms of asphalt stiffness.
Effects of Slab Temperature Profiles on Use of Falling Weight Deflectometer Data to Monitor Joint Performance and Detect Voids
Authors: Vandenbossche Julie M.
Published: January 2008

The primary objective of this research effort is to determine if temperature gradients affect the ability to use falling weight deflectometer (FWD) testing to monitor pavement joint performance and detect voids under the corners of the slab. A field investigation was performed at the Minnesota Road Research System test facility to meet this objective. It was found that gradients can have an effect on the results of FWD testing for rigid pavements. Although the load transfer efficiencies measured for doweled slabs were not found to be affected by slab temperature or temperature gradients (even when poor joint performance was exhibited), load transfer efficiencies measured for the undoweled slabs were greatly influenced by the presence of a gradient. There even appears to be a higher correlation between the gradient present at the time of testing and the average temperature of the slab for the pavement designs and environmental conditions included in this study. Gradients present at the time of testing also affect the ability to detect voids beneath the slab. Large positive gradients produced negative void parameters (indicating that a void was not present), whereas large negative gradients produced large positive void parameters (indicating that a void was present). This study found that loss of support under the slab could be identified even when the joints were locked if gradients were not present. On the basis of these findings, it is important to determine the complete temperature profile throughout the depth of the slab at the time of testing so that this information can be considered when the deflection data are interpreted.
Noninvasive Measurement of Three-Dimensional Permanent Strains in Asphalt Concrete with X-Ray Tomography Imaging
Authors: Wang Yongping , Wang Linbing , Harman Tom , Li Qingbin
Published: January 2008

Because of the stiffness differences between aggregates and mastics, permanent deformation of asphalt concrete is localized mainly in the soft mastics. Therefore, studies on the microresponse of the aggregates and mastics could provide a better understanding of the macrobehavior of asphalt concrete. A method is presented to measure the deformations in the mastics; this was correlated with the permanent deformation resulting from the asphalt pavement analyzer test. An automated procedure with tomography images to reconstruct three-dimensional particles was developed. The translations of the particles can be obtained from the coordinate differences of the mass centers before and after testing. The microstrains in the mastics and macrostrains in the mixture can be calculated on the basis of particle translations. The procedures described have significance for future study on how the aggregated shape, size, and arrangement affect the macroresponse of the mixture in three dimensions and how the relative stiffness of aggregates and mastics affects rutting potential.
Development of Control Strategy for Intermodal Connection Protection of Timed-Transfer Transit Routes
Authors: Chung Eui-Hwan , Shalaby Amer
Published: January 2008

Intermodal transfer time is one of the most significant components of transit travel from the perspective of passengers. Even in a well-coordinated transit network, operational control is necessary to maintain the coordinated transfers that may be disrupted because of unexpected delays of transit vehicles. Connection protection (CP) involves holding a transit unit to wait for another transit unit that is planned to provide a timed transfer but has been delayed. This study proposes a strategy for CP that predicts how the controlled transit unit affects the waiting times of related passengers and determines whether the unit should be held to preserve the connection based on passenger waiting times. The strategy is evaluated with a developed simulator that models transfers from a commuter rail line in the city of Brampton, Canada, to a local bus route. The proposed strategy is compared with two extreme strategies: holding the bus until the train's arrival and operating it without any holding. Results show that the proposed strategy improves transfer efficiency and reduces the waiting times of affected passengers.
Value of Punctuality on Suburban Trains to and from Paris
Authors: Kroes Eric , Kouwenhoven Marco , Duchateau Hugues , Debrincat Laurence , Goldberg Jonathan
Published: January 2008

The research project under discussion aimed to provide an operational methodology to assess the perceived benefits of investments to improve punctuality of suburban rail services to and from Paris. A literature review, train surveys and counts, and a stated preference (trade-off) experiment have been conducted to obtain values of reliability. Also, a simple tool was developed to quantify the benefits of specific projects. This was applied in a case study to the Réseau Express Régional (RER) B Nord+ punctuality improvement project. The research indicated that an improvement in punctuality, expressed as a 5% reduction in the number of trains delayed 5 to 15 min, was worth about 4.6 min of travel time for commuters and students. Comfort appeared to be important, with a particularly clear dislike of standing in crowded trains. Information was also valued as worthwhile: explicit information about the duration of delays (in addition to information about the cause of delays) was valued similarly as a 10-min reduction in travel time. The RER B Nord+ case study indicated that total annual benefits of about €10 million were expected, beyond the €31 million benefits due to travel time savings (€1 = US$1.34 in 2007).
Development of Crash Energy Management Specification for Passenger Rail Equipment
Authors: Strang Jo , Hynes Ron , Peacock Tom , Lydon Bill , Woodbury Cliff , Stastny Jeff , Tyrell David
Published: January 2008

At the time of the Glendale, California, commuter train incident on January 26, 2005, in which 11 occupants were fatally injured, Metrolink (Southern California Regional Rail Authority) was preparing to purchase new equipment. As part of its response to the incident, Metrolink decided to apply results of FRA's research into passenger train crashworthiness in this procurement. Research focuses on the activities of the federal government and rail industry conducted in response to Metrolink's decision. In coordination with APTA and seeking support in developing a specification for crash energy management (CEM) features, Metrolink approached FRA and FTA. FRA, FTA, and APTA decided to form an ad hoc CEM Working Group. A broad-level work plan was then developed. The working group would include participants from the rail industry and government agencies. The plan included a technology transfer symposium to initiate the effort and four meetings. Following this plan, a detailed technical specification was developed in slightly more than 4 months. The research used to develop the specification and an overview of the specification are summarized. Current practice requires that passenger rail equipment be able to support large loads without permanent deformation but does not consider how cars behave when overloaded. CEM prescribes that car structures crush in a controlled manner and absorb energy. CEM can significantly improve crashworthiness: a cab car-led train with CEM features is more crashworthy than a conventional locomotive-led train. This specification is a guide to CEM technology.
Air Travel Consumer Protection
Authors: Sherry Lance , Wang Danyi , Donohue George
Published: January 2008

The raison d'être for the national air transportation system (ATS) is the movement of passengers and cargo. Thus, passenger trip time performance is positively correlated with passenger satisfaction, airfare elasticity, and airline profits. Regulatory consumer information available to airline passengers provides measures of trip performance by using the percentage of on-time flights or on-time percentage (OTP) (e.g., 15-OTP metric). Researchers have shown that these flight-based metrics are poor proxies for passenger trip time performance. First, these metrics do not include the trip delays accrued by passengers rebooked because of canceled flights (which account for 40% of the overall passenger trip delays). Second, the metrics do not quantify the magnitude of the delay (only the likelihood) and thus fail to provide the consumer with a useful assessment of the impact of a delay (such as missed connections on next mode of transportation). A new consumer protection metric, expected value of passenger trip delay (EV-PTD), is described; it accounts for (a) canceled flights and (b) both the probability of delay and the magnitude of the delay. The EV-PTD for all 1,030 routes between 35 Operational Evolution Plan airports in 2005 ranged from 11.5 min (best) to 155 min (worst). The average route EV-PTD was 35 min. By treating passenger trip delay as a random variable it can be shown that the transportation process is not a fair game and that passengers and service providers (e.g., airlines, air traffic control, airports) cannot beat the system until the variance is significantly reduced. The implications of these results and the use of the EV-PTD metric by consumers for purchasing tickets and for consumer protection are discussed.
Modeling Joint Choice of Airline Itinerary and Fare Product
Authors: Carrier Emmanuel
Published: January 2008

The rapid expansion of low-cost airlines and the development of online distribution of airline tickets have put pressure on the pricing and revenue management strategy of network airlines and have substantially modified the airline passenger choice environment, especially in short-haul markets. To analyze the choice behavior of airline passengers, a unique data set is being developed. Passenger booking data are combined with fare class availability data collected daily for a 90-day booking period, and fare rules are applied to reconstruct the passenger choice set and determine which fare products were available at the time of the booking on nonstop itineraries in select business-oriented European short-haul markets. Estimation results from a multinomial logit model of the joint choice of airline itinerary and fare product show that outbound passengers tend to prefer early morning and late afternoon flight departures that allow them to conduct their business activities either before or after their trips. In addition, a significant proportion of passengers traveling during the week tends to prefer higher-priced fully flexible fare products to cheaper nonflexible options; this preference shows the revenue potential of a multiproduct pricing strategy in markets affected by the presence of low-cost competition. This study illustrates how such models may be used to support airline decision making in scheduling, pricing, and revenue management.
Design of Product Recovery Networks under Uncertainty
Authors: Lee Der-Horng , Dong Meng , Bian Wen , Tseng Yuan-Jye
Published: January 2008

The design of product recovery networks has received growing attention in the past decades. Because of the number of processing activities involved and the variability in the value of the components, these problems present a high level of uncertainty. This paper proposes a stochastic programming-based approach in which a deterministic model for product recovery network design can be extended to account for uncertainties explicitly. Because almost all existing approaches for solving such problems are either restricted to deterministic situations or can deal only with a modest number of scenarios for the uncertain problem parameters, a solution approach integrating a recently proposed sampling method with an acceleration strategy is developed. A computational study involving a large-scale product recovery network is presented to demonstrate the significance of the developed stochastic model as well as the efficiency of the proposed solution approach.
Evaluation of Delivery Consolidation in U.S. Urban Areas with Logistics Cost Analysis
Authors: Kawamura Kazuya , Lu Yandan
Published: January 2008

One of the most promising strategies for reducing truck traffic in urban centers is the consolidation of consignments through cooperation and coordination among multiple businesses. However, various factors—including existing infrastructure systems, institutional and regulatory environments, socioeconomic and geographical characteristics, political climates, past and future changes in logistics and supply chain management, and market forces—will determine whether such a strategy can be adopted and function effectively in the United States. In this paper, the cost-effectiveness of a common type of consolidation scheme used in foreign countries is examined against the peddle-run system commonly used in the United States. The analysis results indicate that the current U.S. distribution system has substantial cost advantages. Demographic factors, population density, and urban area size, while having some effect on the logistics cost under the consolidation system, do not reverse the cost advantage of the peddle-run system within the range tested. The advantage of the peddle-run system will not be overcome without drastic policy changes, the imposition of truck size and weight restrictions, or investments in public terminals.
Estimating Truck Trip Origin–Destination with Commodity-Based and Empty Trip Models
Authors: Raothanachonkun Pairoj , Sano Kazushi , Wisetjindawat Wisinee , Matsumoto Shoji
Published: January 2008

This study estimates origin–destination (O-D) matrices of light and heavy trucks on the basis of the flow of commodities in the Tokyo metropolitan area. The truck O-D matrix is generally determined by either vehicle trip-based or commodity-based approaches, although the former cannot distinguish between loaded and empty trips and does not characterize the shipments. Three major concepts are proposed in this study. First, the truck trip O-D is estimated on the basis of the commodity approach because it can utilize the characteristics of the shipments. Second, the main contribution of the model is its ability to estimate both loaded and empty trips by modeling the truck movements as round trips and trip chains. The O-D of truck movement, particularly the movement of loaded trips in round trips or zero-order trip chains, is similar to that of the commodity flows. However, both movements have relatively different O-D when the loaded trips travel from one origin to many destinations or are part of an nth-order trip chain. Finally, the trip chain is modeled on the basis of characteristics such as average payload, adjacent zones, and the commodity O-D providing the most attractive zones traveled by trucks. The performance of the model is demonstrated by using the mean square error between the estimated and observed truck O-D matrices. The model concept is then applied to lightweight products obtained from the food industry. The proposed concept enhances the trip chain behavior and provides better results than the model without trip chain behavior.
Integrated Origin–Destination Synthesis Model for Freight with Commodity-Based and Empty Trip Models
Authors: Holguín-Veras José , Patil Gopal R.
Published: January 2008

Origin–destination (O-D) synthesis techniques offer the potential of producing estimates of freight O-D matrices by using secondary sources such as traffic counts, bypassing the need for expensive data collection efforts. In the case described in this paper, this promise is particularly important because of the significant cost associated with conducting surveys to obtain O-D patterns of freight movements and because of the reluctance of freight providers to provide information they consider commercially sensitive. The paper proposes an integrated O-D synthesis model that combines a commodity-based model to estimate loaded truck trips with a complementary model of empty trips. This integration is important because explicit modeling of empty trips—which account for 30% to 40% of total truck trips—is required to avoid significant errors in the estimation of directional traffic. The proposed model is applied to a case study for which both the actual O-D matrix and traffic counts are known. Two objective functions are considered for the proposed model based on two scenarios: (a) only total link traffic is known and (b) only the split of loaded and empty link traffic is known. With data from a case study, it was found that the proposed model performs significantly better than an alternative formulation that does not consider an empty trip model. In addition, it is observed that the added information in terms of observed empty trips improves the O-D estimates. The model was found to produce reasonable estimates of the true parameters of the underlying models.
Shipper Preferences Suggest Strong Mistrust of Rail
Authors: Patterson Zachary , Ewing Gordon O. , Haider Murtaza
Published: January 2008

The Quebec City–Windsor corridor is the busiest and most important trade and transportation corridor in Canada. The transportation sector is the second-largest contributor to greenhouse gas emissions in the country. Governments around the world, including Canada's, are considering increasing mode share by rail as a way of reducing transportation emissions. To understand whether freight mode shift is a realistic means of reducing transportation emissions, an analytical model is needed that can predict the effect of government policy on mode split. This paper presents the findings of the first such model developed for the Quebec City–Windsor Corridor. The model itself is a stated preference carrier choice model of shippers in this busy route. The model was developed by using the results of a stated preference survey undertaken in fall 2005. The survey was designed explicitly to evaluate shipper preferences for the carriage of intercity consignments, particularly their preferences for carriers that contract the services of rail companies to carry these shipments via rail. The results of the study (a) show that shippers are mistrustful of using rail to move their consignments and (b) suggest that increasing rail's share of freight transport faces tremendous challenges.
Traffic Safety and Safe Routes to Schools
Authors: Dumbaugh Eric , Frank Lawrence
Published: January 2008

Safe Routes to Schools programs are an increasingly popular means of addressing parental concerns about traffic safety and encouraging parents to permit their children to walk and bicycle to school. While there has been a good deal of recent research examining the health and physical activity benefits associated with these programs, there has been little systematic examination of the effects these programs may have on the actual safety of child pedestrians. This paper summarizes the existing empirical evidence on the behaviors known to lead to crashes involving child pedestrians, as well as the effects that 10 safety countermeasures commonly incorporated into Safe Routes to Schools programs have on both the incidence of crashes involving child pedestrians and the behaviors known to result in such crashes. The paper finds that many safety benefits associated with these countermeasures are assumed rather than known and that there are substantial gaps in the existing knowledge about the specific safety effects of the components of Safe Routes to Schools programs. It concludes by identifying opportunity areas for future research on this important topic.
Revealed Parking Choices and the Value of Time
Authors: Harmatuck Donald J.
Published: January 2008

This study uses 2005–2006 University of Wisconsin–Madison (UW–Madison) parking applications to model lot choice in terms of parking prices and walking distances and to determine how parkers value their walking times. UW–Madison employees apply for annual lot parking permits each year by ranking as many as four lots; the employees know that the highest ranked lot with available space will be offered to them. Parking choices are modeled as functions of walking distances, lot prices, and department priority indexes that reflect income, seniority, and status. The sample consists of 4,032 employees who work in 150 campus buildings and park in more than 60 lots. Lot prices vary from $435 to $1,025 per year, and walking distances from workplaces to lots range from a few feet to nearly 2 mi. The results are consistent across specifications. The estimated values of walking time vary from less than $4/h for low-status employees parking in low-priced lots to more than $30/h for high-status employees in high-priced lots. Choice is relatively inelastic regarding distance and more elastic regarding price. Choice models are used to estimate the effects of two price changes: ( a) a single $650 annual lot price and ( b) a $250 increase for all prices.