bluuebunny/crossref_metadata_2025 huggingface dataset:
Factors Affecting Benefits of Implementing Special Signal Timing Plans for Inclement Weather Conditions
Authors: Agbolosu-Amison Seli J. , Sadek Adel W. , Henry Brandon
Published: May 2018

Gridlock along arterial systems in cold climates is often the result of adverse weather conditions, which can render the normal signal coordination plans unsuitable as a result of changes in the traffic flow parameters. The current study aims at understanding the impact of different factors on the magnitude of the operational benefits to be expected from implementing special timing plans for inclement weather. The factors investigated include ( a) the characteristics of the signalized corridor, ( b) the type of the simulation model used in the evaluation, ( c) the level of traffic demand, and ( d) the duration of the inclement weather event. To achieve the study's objective, two signalized arterial corridors are selected as case studies, and several simulation experiments are conducted. The results show that signal retiming during inclement weather can result in significant operational benefits (as high as a 20% reduction in control delay in some cases). The results also show that the benefits appear to be greatest when traffic loads are close to capacity and tend to decrease when the available capacity is exceeded. Finally, a significant increase in the benefits is realized with the increase in the duration of the inclement weather event. In one experiment, retiming the signals resulted in a 36% reduction in control delay for a 2-h snow event as opposed to only 18% for a 1-h event.
Traveler Preference for Park-and-Ride Facilities
Authors: Bos Ilona , Van der Heijden Rob , Molin Eric , Timmermans Harry J. P.
Published: May 2018

This paper reports the main findings of a study, conducted in the Netherlands, aimed at testing whether preference functions for park-and-ride facilities, estimated from data collected in a specific Dutch region, can be generalized to a nationwide sample. Preference data in both samples were collected with hierarchical information integration. Contrast parameters were used to test the equality of a set of parameters for decision constructs that were assumed to influence the choice of park-and-ride facilities. Results suggest that the estimated preference functions for the two samples are largely the same within conventional statistical error bounds and provide empirical evidence of generalizability. In addition to the academic importance of this finding, for practitioners it means that no tailored-made research is required to assess the feasibility of such new park-and-ride facilities, especially if the results of this study are further replicated in other contexts and regions.
Latent Activities
Authors: Ettema Dick
Published: May 2018

This paper describes a discrete continuous Tobit model of activity participation and duration. The model extends existing models by accounting for multiple activities and the effect of travel time needed for activity participation on time allocation. The effect of travel time was operationalized by incorporating the travel time ratio into the time allocation procedure. The model was tested on a Dutch data set and appears to outperform less advanced models. The model provides a useful tool for assessing the effect of spatial and transportation policies on individuals’ time allocation and their ability to realize so-called latent activities.
Integrating Prospect Theory and Stackelberg Games to Model Strategic Dyad Behavior of Information Providers and Travelers
Authors: Han Qi , Dellaert Benedict G. C. , Van Raaij W. Fred , Timmermans Harry J. P.
Published: May 2018

Existing policy models of optimal guidance strategies are typically concerned with single-objective optimization based on reliable forecasts in terms of the consistency between predicted and observed aggregate activity–travel patterns. The interaction and interdependencies between policy objective and individuals have not received much attention. This paper considers how one specific activity schedule choice–-namely, the start time of an activity chosen by individual travelers under guidance information–-aggregates to form an equilibrium distribution, which in turn influences guidance generation and determines the best possible achievement of the policy objective. These choices are formalized as the outcomes of a Stackelberg game in which a traveler's behavior model is integrated with prospect theory. The properties of the model are examined by using numerical computer simulations. The results of the simulations support the face validity of the formulated model.
Joint Modeling of Advanced Travel Information Service, Habit, and Learning Impacts on Route Choice by Laboratory Simulator Experiments
Authors: Bogers Enide A. I. , Viti Francesco , Hoogendoorn Serge P.
Published: May 2018

A conceptual modeling framework is proposed, and mathematical submodels for route choice on motorways and urban networks are derived. The models convey the most relevant aspects that play a role in route choice, including learning, risk attitude under uncertainty, habit, and the impacts of advanced travel information service on route choice and learning. To gain insight into the relative importance of the different aspects and processes of route choice behavior, which support the proposed conceptual framework, the models were estimated with data from two experiments carried out with a so-called interactive travel simulator. The latter is a new research laboratory that combines the advantages of both stated preference and revealed preference research. Many relevant contributions on the aforementioned aspects that play a role in route choice can be found in the literature, but a simultaneous consideration of all is lacking. On the basis of these contributions from the literature, a conceptual framework that integrates these aspects was developed. The results from the laboratory experiments indicate that people perform best under the most elaborate information scenario and that habit and inertia together with en route information play a major role in route choice. Learning about route attributes is especially important during the first days but then plays a smaller role than the provided information and the developed habit. Finally, the way information is presented has a great impact on route choice.
Classification Taxonomy and Empirical Analysis of Work Arrangements
Authors: Yeraguntla Aswani , Bhat Chandra R.
Published: May 2018

The work-related characteristics of an individual act as pegs around which other nonwork activities are scheduled on a day-to-day basis. In this paper, four dimensions of the medium- to long-range work arrangements that are important to day-to-day temporal and spatial characteristics of work patterns (and hence to day-to-day activity–travel schedules) are identified. The four dimensions are full-time versus part-time employment, teleworking or not, inflexible or flexible work schedules, and regular or alternate shifts. This paper develops a comprehensive taxonomy of work arrangements in each of these four dimensions and empirically analyses the factors affecting the work arrangement decisions along three of these dimensions.
Coordination of Transit and School Busing in Iowa
Authors: Kroeger Dennis , Andrle Steve , Hallock Peter
Published: May 2018

The 2003 Iowa General Assembly asked the Iowa Department of Transportation (DOT) to conduct a study of Iowa public policy on coordination of public transit services and school transportation. The legislature's request, contained in the transportation appropriation bill, required “a report pertaining to the efficiencies that may be gained by the coordination of transit management and maintenance systems in the areas of school transportation, public transit, and other forms of public transportation.” Such efficiencies are described. As requested by the Iowa DOT, the Center for Transportation Research and Education at Iowa State University studied these issues and prepared a report for the Office of Public Transit. A summary of the coordination activities that are taking place in Iowa between the school districts and transit agencies is presented. Furthermore, the levels of coordination and what benefits are derived from coordinating services are discussed. The objectives of the study include the following: to examine the legal basis for such coordination in Iowa; to inventory the types of coordination taking place around the state; and to highlight some of the coordination models, with a discussion of what each party believes are the benefits of the coordination as well as obstacles that have been encountered.
Transit-Based Smart Parking in the San Francisco Bay Area, California
Authors: Rodier Caroline J. , Shaheen Susan A. , Eaken Amanda M.
Published: May 2018

This paper presents early findings from an application of advanced parking technologies to increase effective parking capacity at a transit station during the first half of 2004 in the San Francisco Bay Area, California. It begins with an extensive review of the literature related to transit-based smart parking management systems to illustrate the range of system configurations and their potential travel, economic, and environmental effects. Two important conclusions from this review are that the lack of parking spaces at transit stations may be a significant constraint to transit use and that pretrip information and perhaps en route information on parking availability at transit stations may increase transit use. A survey of commuters at the Rockridge Bay Area Rapid Transit (BART) station was implemented to gain insight into parking information needs, the travel effects of a new monthly paid parking program, and the potential travel effects of a smart parking service. First, it was found that a potential market existed for a daily paid parking information service among current and new riders with relatively high incomes, high automobile availability, and variable work locations and schedules. Second, the current monthly reserved paid parking service might have increased the frequency of BART use among subscribers, but it might not have reduced net auto travel for two reasons: subscribers appear to have switched to BART for their main commute mode from carpool, bus, and bike modes; and subscribers might have increased their use of the drive-alone mode to access the BART station.
Structural Equation Modeling to Determine Passenger Loyalty toward Intercity Bus Services
Authors: Wen Chieh-Hua , Lan Lawrence W. , Cheng Hsiu-Ling
Published: May 2018

This paper investigates passenger loyalty to intercity bus services and identifies important factors influencing loyalty. The relationships between passenger loyalty and other latent factors, including satisfaction, service value, service quality, sacrifice, switching costs, attractiveness of competitors, and trust are hypothesized and tested. Factor analysis is used to extract the latent service quality factors from a large number of service quality indicators. Structural equation models are then developed to elucidate the causal relationships of passenger loyalty and the latent factors. The empirical results have confirmed the proposed hypotheses. Satisfaction has the most significant influence on passenger loyalty. Service value, switching costs, and trust have direct and positive effects on loyalty, whereas attractiveness of competitors has a direct negative effect. The indirect effect of service quality, via service value and satisfaction, on passenger loyalty is also significant. From the empirical results, managerial implications for the bus carriers are addressed.
Load Rating of Prestressed Concrete Girder Bridges
Authors: Rogers Brandy J. , Jáuregui David V.
Published: May 2018

In light of the adoption of the load and resistance factor design (LRFD) philosophy by the AASHTO Subcommittee on Bridges and Structures, research efforts are under way to facilitate the transition from load factor rating (LFR) to load and resistance factor rating (LRFR) in New Mexico. Five prestressed concrete girder bridges, courtesy of the New Mexico bridge inventory, were rated with the BRASS-GIRDER and BRASS-GIRDER (LRFD) structural software. The objectives for this study were to evaluate and verify the BRASS (bridge rating and analysis of structural systems) software, to identify the source of dissension between LFR and LRFR rating factors, and to examine any trends in the rating factors as affected by bridge geometry. The comparison of LFR and LRFR focused on both flexure and shear for the strength limit state. The LRFR method generally yielded lower rating factors for flexure, with the longer-span bridges demonstrating a larger deviation between LFR and LRFR. The live load effects were identified as the major factor contributing to the difference in flexure ratings; the dead load effects and flexural resistance had little effect. The LRFR rating factors for shear also were generally lower than those produced by LFR. The discrepancy in the shear ratings was caused by both the live load effects and shear resistance. The dead load effects contributed little to the variation in LFR and LRFR rating factors for shear. Overall, the shear ratings controlled over those based on flexure.
Analysis of Tensile Stresses in Transfer Zone of Prestressed Concrete U-Beams
Authors: Huang Dongzhou , Shahawy Mohsen
Published: May 2018

Prestressed U-beam bridges compare favorably in cost and appearance to traditional concrete I-beam bridges. Consequently, U-beam bridges are gaining in popularity and usage, especially when aesthetic issues are deemed important. U-beam bridges first appeared in Florida in 2000; however, during construction, cracks developed in the webs of the U-beams. This paper presents results of an analysis of representative cracking of U-beams and proposes a practical method for the transfer zone stirrup design. For the purpose of the analysis, the U-beam is divided into a series of finite shell-plate elements, and the prestressing tendons are simulated as a number of concentrated forces. Two different mechanical models of the U-beams are developed on the basis of the stages of construction. Analytical results show that high tensile stresses occur in the end zone of the U-beam because of the prestressing tendons and that these tensile stress must be properly considered in bridge design. The research results are applicable to the design of prestressed U-beams and similar types of prestressed girders.
Single-Lane Live Load Distribution Factor for Decked Precast, Prestressed Concrete Girder Bridges
Authors: Millam Jason L. , Ma Zhongguo (John)
Published: May 2018

The live load distribution factor equations provided by AASHTO load and resistance factor design specifications for the decked precast, prestressed concrete (DPPC) girder bridge system do not differentiate between a single-lane or a multilane loaded condition. This practice results in a single-lane load rating penalty for DPPC girder bridges. This paper determines distribution factor equations that accurately predict the distribution factor of the DPPC girder bridge system when it is subjected only to single-lane loading. Eight DPPC girder bridges were instrumented. Each bridge was loaded with a single load vehicle to simulate the single-lane loaded condition. The experimental data were used to calibrate grillage models of the DPPC girder bridge system. The calibrated grillage models were used to conduct a parametric study of the DPPC girder bridge system subjected to a single-lane loaded condition. Four new equations that describe the single-lane loaded distribution factor for both shear and moment forces of these bridges are developed in this paper.
Evaluation of Steel Girder Bridge Strengthened with Carbon Fiber–Reinforced Polymer Posttension Bars
Authors: Lee Yoon-Si , Wipf Terry J. , Phares Brent M. , Klaiber F. Wayne
Published: May 2018

This project investigated the effectiveness of carbon fiber–reinforced polymer (CFRP) composite materials to strengthen an existing, structurally deficient steel girder bridge. The bridge selected for strengthening with the CFRP posttensioning system is a three-span continuous steel stringer bridge on IA-141 approximately 1.6 mi west of Bayard, Iowa. The research program consisted of several tasks, and the main emphasis was the installation of the strengthening system and associated field testing. The bridge was instrumented to measure strain at selected critical locations and tested before installation of the posttensioning system, shortly following posttensioning, and after approximately 1 and 2 years of service to assess changes in behavior resulting from the addition of the posttensioning system and time. During the application of the posttensioning strengthening system, strain was measured to investigate the response of the bridge to the applied posttensioning forces. After the last follow-up test was completed, the posttensioning force was removed (and reapplied) to investigate any loss of posttensioning force that may have occurred during the 2-year period. In general, the installation of the posttensioning system required no special equipment or training other than access equipment, an acetylene torch to remove a portion of several diaphragms, and a hydraulic jack. A three-person crew was able to install the system in just over 1 day. On the basis of an analysis performed by using an HS-20 truck, it was found that the posttensioning strengthening system reduced the dead and live load induced moments by approximately 3% to 5%, allowing the bridge to carry additional live load.
Acousto-Ultrasonic Technology for Nondestructive Evaluation of Concrete Bridge Members Strengthened by Carbon Fiber–Reinforced Polymer
Authors: Ekenel Mahmut , Galati Nestore , Myers John J. , Nanni Antonio , Godínez Valery
Published: May 2018

Carbon fiber–reinforced polymer (CFRP) composites have been used in a wide range of application areas in bridge rehabilitations because these materials are less affected by corrosive environmental conditions, are known to provide longer life, and require less maintenance. However, the quality control and quality assessment of these new rehabilitation systems should be further improved and standardized. A recent rehabilitation project that used CFRP laminates was done on a bridge in Dallas County, Missouri, by the Missouri Department of Transportation and the Center for Infrastructure Engineering Studies at the University of Missouri–Rolla. The acousto-ultrasonic nondestructive testing technology was performed to detect and image surface defects in the form of delaminations. These were intentionally formed at the CFRP sheet–concrete interface to investigate the ability of this technique. Acousto-ultrasonic nondestructive testing has shown the ability to detect and image the delaminations between CFRP sheet and concrete substrate.
Establishment of the Precision of a Rapid-Angle Measurement Device for Superpave Gyratory Compactors
Authors: Hall Kevin D. , Easley Tamara
Published: May 2018

Superpave® hot-mix asphalt (HMA) specimens are compacted in the laboratory with the Superpave gyratory compactor (SGC) through pressure and an applied angle of gyration. The original compaction specification for the SGC requires the angle of gyration to be 22 ± 0.35 mrad (1.25 ± 0.02 degrees), measured externally to the compaction mold. Questions concerning the ability of different compactors to produce HMA specimens of the same mix with the same density led to the development of the dynamic angle validation (DAV) kit, which measures the angle of gyration internally (on the inside of the mold). The DAV procedure requires the use of HMA to measure the internal angle of gyration. Because of practical limitations of performing measurements with HMA and questions concerning the “proper” HMA mix to use in the measurements, a device–-the rapid-angle measurement (RAM)–-was introduced to simulate effectively the load placed on the SGC by an HMA specimen. An interlaboratory study was conducted in accordance with ASTM E691-99 to establish the precision of the internal angle measurement provided by the RAM. A total of 11 RAM units and five SGC models were included in the study. On the basis of the study data, estimates were developed of both repeatability (within lab) and reproducibility (between lab) for the RAM device for all five SGC models. It is recommended that all devices with the reported ability to measure internal angle of gyration be subjected to a similar interlaboratory study to compare devices on an equal basis.
Evaluation of Two Compaction Levels for Designing Stone Matrix Asphalt
Authors: Xie Hongbin , Watson Donald E. , Brown E. Ray
Published: May 2018

Current stone matrix asphalt (SMA) design guidelines list two compaction options to design SMA, 50 blows Marshall or 100 gyrations with the Superpave® gyratory compactor (SGC). However, some states have found that 100 gyrations with the SGC is excessive for their materials. In this study a lower compaction level of 65 gyrations was used to compare with the standard 100 gyrations to design SMA mixtures. Results showed that mixtures designed by 65 gyrations had an average of 0.7% higher optimum asphalt content and 1.5% higher voids in mineral aggregate (VMA) than those designed by 100 gyrations. All mixtures designed by 65 gyrations met the minimum asphalt content and VMA requirements for SMA, whereas only eight of 15 mixtures designed by 100 gyrations met those two requirements. Compaction at 100 gyrations resulted in an additional 0.62% average aggregate breakdown at the critical sieve as compared with 65 gyrations. SMA mixtures designed by 65 gyrations and 100 gyrations had an average asphalt pavement analyzer rut depth of 3.9 mm and 3.1 mm, respectively. Thirteen of 15 mixtures designed by 65 gyrations performed well if 5.0 mm was set as the maximum allowed rut depth. On the basis of this study, 65 gyrations can be used to design a more durable SMA mixture, while still maintaining the good rutting resistance that SMA mixtures are noted for. The successful design by 65 gyrations for all five aggregates in this study indicates that a lower design compaction level may allow the use of more aggregate sources for SMA mixtures.
Experimental Investigation of Anisotropy in Asphalt Concrete
Authors: Underwood Shane , Heidari A. Homayoun , Guddati Murthy , Kim Y. Richard
Published: May 2018

Accurate multiaxial characterization of asphalt concrete requires a thorough understanding of its anisotropic behavior. For that purpose a study has been conducted to examine the anisotropic properties of asphalt concrete in the linear viscoelastic range, with growing damage, and during volumetric deformation. Tests were conducted on specimens cored in the vertical and horizontal directions from gyratory-compacted specimens. Anisotropy was found to have no effect on the linear viscoelastic properties of the material. This finding is supported by subsequent results from monotonic constant crosshead rate uniaxial tension and uniaxial compression tests. It was also found that anisotropy contributes greatly to the behavior of asphalt concrete in compression, but shows little, if any, effect on tensile properties. In addition, the strong dependence of anisotropy on temperature and strain rate is presented. Finally, promising results from a simplified method of extracting the anisotropic behavior of asphalt concrete with the use of the hydrostatic test are also introduced.
Influence of Changes in Level on Passenger Route Choice in Railway Stations
Authors: Daamen Winnie , Bovy Piet H. L. , Hoogendoorn Serge P.
Published: May 2018

In assessing the design of a public transfer station, it is important to be able to predict the routes taken by passengers. Most simulation tools use simple route choice models that take into account only the shortest walking distance or walking time between a passenger's origin and destination. To improve this type of route choice model, other factors affecting passenger route choice need to be identified. Also, the way these factors influence route choice behavior needs to be determined to indicate how each factor is valued. In this research, route choice data have been collected in two Dutch train stations by following passengers through the facility from their origins to their destinations. These data have been used to estimate extended route choice models. The focus is on the influences of level changes in walking routes on passenger route choice behavior. It appears that ways of bridging level changes (ramps, stairs, escalators) each have a significant and different impact on the attractiveness of a route to a traveler.
Impacts of Rail Transit on the Performance of a Transportation System
Authors: Litman Todd
Published: May 2018

This paper summarizes research on the effects of rail transit on the performance of transportation systems in major U.S. cities. It summarizes results from the study Rail Transit In America: Comprehensive Evaluation of Benefits, which evaluates rail transit benefits on the basis of comparison of transportation system performance in major U.S. cities. It finds that cities with larger, well-established rail systems have significantly higher per capita transit ridership, lower average per capita vehicle ownership and mileage, less traffic congestion, lower traffic death rates, and lower consumer transportation expenditures than otherwise comparable cities. These findings indicate that rail transit systems can provide a variety of economic, social, and environmental benefits and that benefits tend to increase as a system expands and matures.
Improving Inner-City Mobility with Commuter Rail Service
Authors: Nelson David , Duse-Anthony Yawa , Friemann Scott
Published: May 2018

Public transportation is critical for mobility in most large cities in the United States. In Boston and eastern Massachusetts, the Massachusetts Bay Transportation Authority (MBTA) offers subway, bus, ferry, and commuter rail service to provide options to personal automobile use and thereby reduce highway congestion, improve air quality, and reduce energy consumption. In recent years, scholarly research has suggested that railroads in the city represent an overlooked rail transit opportunity for inner-city mobility. The MBTA's Fairmount Commuter Rail Line passes through some of the most densely populated neighborhoods in the region, yet residents seldom use the line for travel. Instead, Fairmount corridor residents tend to use private automobiles and the overcrowded bus and rapid transit network to travel to downtown Boston. This report documents the methods, findings, and recommendations of a 14-month planning study to investigate strategies that would increase the attractiveness and utility of MBTA services on this underutilized line. The paper then suggests where and how the findings of the Fairmount project might be applied for other inner-city corridors.
Development and Evaluation of Aggregate Destination Choice Models for Trip Distribution in Florida
Authors: Chow Lee-Fang , Zhao Fang , Li Min-Tang , Li Shi-Chiang
Published: May 2018

Discrete choice modeling techniques have been used to model simultaneously the effects of land use and socioeconomic and demographic characteristics on travel behavior. To evaluate the performance of destination choice models with aggregate alternatives at the level of the travel analysis zone in allocating trips between zone pairs, this study developed three sets of home-based work models by using data collected from Broward, Palm Beach, and Volusia Counties in Florida. An objective for this study was to identify the benefit of destination choice models to urban areas of different sizes and characteristics. The spatial distribution patterns from the models were compared with those obtained from gravity models. The results from this study show that all urban areas benefited from destination choice models regardless of the urban size.
Attitudes and Behavioral Responses to Measures to Deal with Workplace Parking
Authors: Farrell Séona , O'Mahony Margaret , Caulfield Brian
Published: May 2018

The relationship between high levels of car usage and the failure to charge car users the true costs of driving is well documented. One of these costs is the cost of parking; of particular concern is the failure of employers to charge employees this cost. This paper aims to investigate employees’ attitudes and potential travel behavior responses to measures selected to deal with parking in the workplace. A survey of university employees examined the employees’ responses to the removal of free car parking spaces, to parking cash-out policies, and to workplace parking charges. The results tend to support related research indicating that cash-out schemes are more popular if they are flexible. An analysis of the data examines the impact of a number of variables on the results; differences in responses by gender, age group, and income are observed. Altogether, 28% of respondents indicated that they would continue to drive to work if a € 5 daily charge was applied, and a similar number said that they would use public transport on some days. In response to a parking cash-out scheme, 66% of respondents indicated that they would continue to drive to work. Individuals’ preferred cash-out method was to give up their car parking space on a daily basis.
Quality Control Procedures for Underwater Inspections
Authors: Rowe Jeffrey B.
Published: May 2018

For more than 20 years, the FHWA has required that underwater inspection of bridges be performed at least every 5 years. Over that period, departments of transportation and other bridge owners have either developed in-house underwater inspection teams or hired outside consultants to perform this work. Ensuring that the inspections are conducted properly and accurately is critical. To this end, several policies and procedures can be implemented as quality control measures in an underwater inspection program. Selecting a properly trained inspection team, ensuring proper preparation before diving operations, conducting independent inspections, and looking at deterioration trends are several ways to ensure quality in underwater inspections.
Investigation of Bonding Condition in Concrete Overlay by Laboratory Testing, Finite Element Modeling, and Field Evaluation
Authors: Nishiyama Taizo , Lee Hosin (David) , Bhatti M. Asghar
Published: May 2018

To evaluate the effect of bonded versus unbonded condition in concrete overlay structure, a field evaluation, laboratory experiment, and 3-D finite element analysis (FEA) model were carried out. First, a field evaluation of bonded and unbonded pavement test sections in Iowa was performed. Cores were extracted from existing pavements and tested for their bond strengths with shear testing equipment. The bond strength between an overlay and the existing pavement gradually increased over time, regardless of the initial bond strength. In some cases, an insufficient bond shear strength at the interface between the concrete overlay and the existing pavement seemed to have contributed to increased distress on the overlay surface. Second, a laboratory experiment was conducted to investigate an effect of bonding in pavement structure. Concrete cylinder specimens that were one-half regular concrete and one-half polymer concrete were fabricated, and their indirect tensile strength was measured at the bonding interface. The experiment results indicated that polymer concrete samples exhibited higher indirect tensile strength than regular concrete samples at the interface. Finally, a 3-D FEA model using eight-node solid elements and a spring element was developed to quantify the bonding level. This model can simulate various bond levels from fully bonded to unbonded by a change of the stiffness of the spring element. The most appropriate spring stiffness was identified for different bonding conditions of overlaid pavements. A parametric study was conducted with spring stiffness changed to develop a matrix that can be used to quantify different levels of bonding. This matrix can help pavement engineers select the most appropriate spring stiffness for a given bonding condition and overlay thickness.
Integrated Field and Office Tools for Bridge Management
Authors: Adams Teresa M. , Juni Emil , Siddiqui Mohsin Khalid , Dzienkowski James E.
Published: May 2018

The Wisconsin Department of Transportation's (WisDOT) Bureau of Structures Data Consolidation Project brings together all bridge-related data into a single data warehouse, the Highway Structures Information System (HSIS), which includes inventory, inspection and maintenance records, and maintenance costs. With the new HSIS, WisDOT's interactive bridge inspection forms and data procedures became incompatible. This conflict presented a timely opportunity to investigate alternative data collection tools that would be practicable in the field. This paper investigates the use of alternative field data collection technologies for bridge inspectors. The participation of bridge inspectors in identifying functional requirements led to an assembly of field tools that included the tablet PC with a shoulder carrying case, a noise-canceling headset microphone, and a tethered pen. Bridge inspectors from six districts volunteered to train on the handwriting and speech recognition technologies and then to test the tools in the field. This paper presents the tool selection process, the technology choices assessed, the training of inspectors, the evaluation of the technology adoption, and the economic benefits of the new technology.
Potential Use of Inventory Theory to Bundle Interventions in Bridge Management Systems
Authors: Adey Bryan Tyrone , Hajdin Rade
Published: May 2018

Before an optimal bridge management strategy can be determined in existing bridge management systems, there must first be a determination of the type and schedule of interventions to be performed on each element of the bridge to achieve a minimal-cost long-term steady state. Once these element-level strategies are known, they are grouped together, or bundled, to develop a management strategy for the bridge. This is currently done with a set of agency rules without regard to whether the bundle of interventions is optimal. Interventions are bundled because it is not desirable to perform interventions on the same bridge in successive years, principally because of user costs. The work discussed here uses inventory theory to bundle interventions on bridges optimally with multiple elements. Two examples are presented. Example 1 shows how a basic joint replenishment model can be used on a multielement bridge to determine optimal management strategies when interventions are bundled and a single-stage policy is used. Example 2 shows how a joint replenishment model with quantity discounts can be used to alleviate some of the problems with a basic joint replenishment model. The optimal management strategy determined in Example 2 is compared with the optimal management strategy determined when interventions are not bundled. Direction for future work is given.
Selecting Preventive Maintenance Treatments in Texas
Authors: Chang Jia-Ruey , Chen Dar-Hao , Hung Ching-Tsung
Published: May 2018

Although the cost-effectiveness of preventive maintenance (PM) treatments for pavement is important, literature addressing this issue is limited. Even under the well-controlled FHWA long-term pavement performance (LTPP) study, incomplete data and sections exist. Criteria for selecting PM treatments often conflict and have to be compromised. The multiple criteria decision-making (MCDM) method is one of numerous approaches available for resolving variations of results. The technique for order preference by similarity to ideal solution (TOPSIS), an MCDM method, was used to analyze successfully all 14 specific pavement study (SPS)-3 sites in Texas. The distress score (DS), international roughness index (IRI), and treatment costs were used as criteria to determine the cost-effectiveness of various PM treatments (thin overlay, slurry seal, crack seal, and chip seal). With TOPSIS, the cost-effectiveness of these treatments can be quantified, with variations caused by subjective judgment thus minimized. When all criteria were considered, the most and least cost-effective methods were chip seal and slurry seal, respectively. When cost was not considered, the most and least effective methods were chip seal and crack seal, respectively. The chip seals performed the best. Chip seals had the most forgiving qualities of all the methods, and they yielded no reflection of the cracking that preceded the treatment applications. The evaluation based on TOPSIS provides a viable option for engineers determining the best PM treatments for pavement in need of maintenance.
Variations in Composition and Rheology of Bituminous Crack Sealants for Pavement Maintenance
Authors: Masson J.-F. , Collins Peter , Bundalo-Perc Sladana , Woods John R. , Al-Qadi Imad
Published: May 2018

Bituminous crack sealants are used for the preventive maintenance of asphalt concrete pavements. The selection of a durable sealant can be difficult, however, mainly because of the lack of correlation between standard sealant specifications and field performance. Hence, an approved list of materials based on past performance is sometimes used to select sealants. However, sealant durability and performance vary over time. To investigate the effect of sealant lot variation on sealant properties, six lots of two sealants from different suppliers were analyzed for filler and polymer contents and rheological response. It was found that the difference in composition and rheology between lots can be similar to that between sealants produced by different manufacturers. Hence, sealant lot-to-lot variation can partly explain the variation in the field performance of sealants. Therefore, lists of approved products drawn from the field performance of past years are ineffective in the selection of sealants for future maintenance. The application of segregated sealants was also investigated, including assessing the effect of melter stirring on sealant homogeneity and measuring the segregation of sealant upon cooling. It was found that sealants do not segregate after their application and subsequent cooling and that a rapid circumferential stirring of 25 revolutions per minute in the heating kettle allowed for the remixing of a segregated sealant.
Nonstationary Kalman Filter for Estimation of Accurate and Consistent Car-Following Data
Authors: Punzo Vincenzo , Formisano Domenico Josto , Torrieri Vincenzo
Published: May 2018

Difficulty in obtaining accurate car-following data has traditionally been regarded as a considerable drawback in understanding real phenomena and has affected the development and validation of traffic microsimulation models. Recent advancements in digital technology have opened up new horizons in the conduct of research in this field. Despite the high degrees of precision of these techniques, estimation of time series data of speeds and accelerations from positions with the required accuracy is still a demanding task. The core of the problem is filtering the noisy trajectory data for each vehicle without altering platoon data consistency; i.e., the speeds and accelerations of following vehicles must be estimated so that the resulting intervehicle spacings are equal to the real one. Otherwise, negative spacings can also easily occur. The task was achieved in this study by considering vehicles of a platoon as a sole dynamic system and reducing several estimation problems to a single consistent one. This process was accomplished by means of a nonstationary Kalman filter that used measurements and time-varying error information from differential Global Positioning System devices. The Kalman filter was fruitfully applied here to estimation of the speed of the whole platoon by including intervehicle spacings as additional measurements (assumed to be reference measurements). The closed solution of an optimization problem that ensures strict observation of the true intervehicle spacings concludes the estimation process. The stationary counterpart of the devised filter is suitable for application to position data, regardless of the data collection technique used, e.g., video cameras.
Development of Multiregime Speed–Density Relationships by Cluster Analysis
Authors: Sun Lu , Zhou Jie
Published: May 2018

Empirical speed–density relationships are important not only because of the central role that they play in macroscopic traffic flow theory but also because of their connection to car-following models, which are essential components of microscopic traffic simulation. Multiregime traffic speed– density relationships are more plausible than single-regime models for representing traffic flow over the entire range of density. However, a major difficulty associated with multiregime models is that the breakpoints of regimes are determined in an ad hoc and subjective manner. This paper proposes the use of cluster analysis as a natural tool for the segmentation of speed–density data. After data segmentation, regression analysis can be used to fit each data subset individually. Numerical examples with three real traffic data sets are presented to illustrate such an approach. Using cluster analysis, modelers have the flexibility to specify the number of regimes. It is shown that the K-means algorithm (where K represents the number of clusters) with original (nonstandardized) data works well for this purpose and can be conveniently used in practice.
Start-Up Delays of Queued Vehicles
Authors: Long Gary
Published: May 2018

Start-up delays of queued vehicles have been studied in past research for evaluation of their impacts on saturation flow rates at downstream traffic signals. A more crucial issue, however, can be the effect of start-up delays of queued vehicles at upstream locations where queued vehicles back up from a traffic signal across a railroad crossing. The relationship between queue start-up delays and track clearance times is important in establishing traffic signal preemption settings. This paper presents models that are developed for prediction of the expected maximum time required to mobilize a queue of any length. The models consider not only the average delay times but also the limiting delay times that are expected to accommodate high proportions of queues. For design convenience, queue lengths are converted into distance from the leading edge of a queue rather than being described only by the number of vehicles in a queue. Because the variations in start-up times, in addition to the average times reported in the literature, are needed, two sets of field studies were used to obtain data for model calibration and to investigate various traffic operation effects. Other factors that might be expected to influence queue start-up times are also analyzed.
Variation in Freeway Lane Use Patterns with Volume, Time of Day, and Location
Authors: Amin Mohammad R. , Banks James H.
Published: May 2018

Lane flow data for five extended freeway segments in the San Diego, California, area were used to examine the effects of freeway and ramp volumes on lane flow distributions and to explore the extent to which these relationships vary by time and location. The proportion of the flow using particular lanes varies significantly with the freeway volume but not with the on-ramp volume. Relationships between freeway volume and the proportion of flow in particular lanes vary significantly by time of day, with flows in different lanes more nearly equal in midday periods than before the morning peak period or after the evening peak period. Such relationships are relatively similar for different days at the same location and different locations within the same extended freeway section but are quite dissimilar for different sections. As a general rule, the proportion of flow in the median lane increases with increasing volume and is greater than that for other lanes in congested flow and high-volume uncongested flow; however, in some cases it increases continuously with increasing volume, and in others it increases up to a point and then decreases. The major implications for behavioral theories of traffic flow are that lane use behavior varies with driver population characteristics and that in making lane use decisions, drivers are sensitive to both speed and vehicle spacing.
Lane-Changing Model with Explicit Target Lane Choice
Authors: Toledo Tomer , Choudhury Charisma F. , Ben-Akiva Moshe E.
Published: May 2018

The lane-changing model is an important component of microscopic traffic simulation tools. With the increasing popularity of these tools, a number of lane-changing models have been proposed and implemented in various simulators in recent years. Most of these models are based on the assumption that drivers evaluate the current and adjacent lanes and choose a direction of change (or no change) on the basis of the utilities of these lanes only. The lane choice set is therefore dictated by the current position of the vehicle and in multilane facilities would be restricted to a subset of the available lanes. Thus, existing models lack an explicit tactical choice of a target lane and therefore cannot explain a sequence of lane changes from the current lane to this lane. In this paper, a generalized lane-changing model that explicitly incorporates the choice of target lane is presented. The target lane is the lane that the driver perceives to be the best when a wide range of factors and goals are taken into account. The immediate direction in which a driver changes lanes is determined by the target lane choice. All parameters of the model were jointly estimated with detailed vehicle trajectory data. The model was validated and compared with an existing lane-changing model with the use of a microscopic traffic simulator. The results indicate that the proposed model performs significantly better than the previous model.
Calibration of Distributions of Commercial Motor Vehicles in CORSIM
Authors: Schultz Grant G. , Rilett Laurence R.
Published: May 2018

One of the most critical aspects of effective microscopic traffic simulation models is proper calibration for accurate replication of both supply and demand characteristics, as well as their interaction. Recent research has begun automating the calibration process by using intelligent transportation system data. This research, however, has targeted automobile traffic and has not generally included commercial motor vehicle (CMV) impacts. Because CMVs are a significant part of the traffic stream and tend to have a disproportionate effect on the transportation system, it is theorized that these vehicles should be included in the calibration process. The objective of this research, therefore, is ( a) to outline calibration parameters and network properties available (including site-specific vehicle distributions with weigh-in-motion and automatic vehicle classification data) for a freeway simulation of both passenger cars and CMVs and ( b) to apply these parameters and network properties on an urban freeway system in Texas by using the microscopic traffic simulation model CORSIM and an auto-mated genetic algorithm calibration methodology. The results of the analysis indicate that the overall calibration measurably improves the ability of the model to replicate observed conditions. The results for this corridor, however, do not support the need to include maximum nonemergency deceleration rates in the calibration process. The inclusion of site-specific vehicle distributions, however, was observed to provide a more accurate representation of vehicle composition and overall network results. This methodology has not been explored previously and provides a strong base for evaluating the impacts of CMVs on the transportation network by the use of microscopic traffic simulation models.