bluuebunny/crossref_metadata_2025 huggingface dataset:
Constitutive Relations for Asphalt Concrete Under High Rates of Loading
Authors: Seibi Abdennour C. , Sharma Mangalore G. , Ali Galal A. , Kenis William J.
Published: April 2007

A main characteristic of asphalt concrete (AC) is its tendency to behave elastically and viscoplastically during cold and hot seasons, respectively. An understanding of the mechanical behavior of AC under various loading conditions is crucial to a more rational design of flexible pavements and requires more elaborate and comprehensive constitutive relations for AC. AC behavior under high rates of loading was experimentally studied using uniaxial, triaxial compression, and pavement simulation tests. The loading matrix followed in the testing program consisted of 0.05-, 0.1-, and 0.2-s loading durations; three stress levels of 207, 414, and 827 kPa; and three temperatures of 24°C, 35°C, and 41°C. The experimental results indicated that AC materials display an elastic-viscoplastic response under uniaxial stress pulses. The viscoplastic response was characterized by the rate dependency of the plastic response and was found to be linearly strain hardening. The results revealed that the yielding point is dependent on the strain rate and temperature and increases as both variables increase. The developed model uses a yield criterion based on the loading function defined by Drucker-Prager. The uniaxial material properties were calibrated to field conditions from the pavement simulation test data through an optimization process that involved iterative calls between finite element results and the optimum parameters, which were obtained using ABAQUS and CONMIN, respectively. This analysis resulted in the development of a generalized elastic-viscoplastic constitutive relation for AC.
Fatigue and Permanent Deformation Models for Polymer-Modified Asphalt Mixtures
Authors: Khattak Mohammad J. , Baladi Gilbert Y.
Published: April 2007

For the past 2 decades, significant research has been conducted on polymer-modified asphalt (PMA) mixtures. Polymers can successfully improve the performance of asphalt pavements at low, intermediate, and high temperatures by increasing mixture resistance to fatigue cracking, thermal cracking, and permanent deformation. Most of the research has been concentrated on the characterization and relative comparison of neat and PMA mixtures, and little work has been done toward the development of fatigue and permanent deformation models for PMA mixtures. A 3-year study that was sponsored by the Michigan Department of Transportation was conducted at Michigan State University to characterize PMA mixtures. It was found that the rheological and engineering properties of PMA mixtures largely depend on the polymer type and content. The improvements in the fatigue lives and resistance to permanent deformation are mainly due to the improvements in the rheological properties of the binders. Fatigue life and permanent deformation models were developed. These models show that the laboratory fatigue life and permanent deformation are strongly related to the rheological properties of binders and the engineering properties of PMA mixtures.
Gradation Effects on Hot-Mix Asphalt Performance
Authors: Hand Adam J. , Stiady James L. , White Thomas D. , Noureldin A. Samy , Galal Khaled
Published: April 2007

The effect of gradation on hot-mix asphalt (HMA) performance has long been a contentious issue. One objective of the National Pooled Fund Study No. 176 was to evaluate the impact of gradation on the rutting performance of HMA. To this end, 21 Superpave mixtures were designed that used a range of materials, nominal maximum size aggregates, and gradations typical of those used throughout the United States. Tests that included both laboratory and prototype-scale loading were used to evaluate the permanent deformation characteristics of the mixtures. Analysis of the data revealed that adequate performance could be obtained with mixture gradations plotting above (ARZ), through (TRZ), and below (BRZ) the restricted zone. Laboratory tests suggested that ARZ and TRZ gradations might provide better deformation resistance than BRZ gradations. However, prototype-scale accelerated pavement testing did not show any clear trends in performance relative to gradation alone with respect to the restricted zone. This means that the restricted zone alone is not adequate to characterize gradation to ensure acceptable rutting performance and should therefore be omitted from Superpave specifications.
Transferability of Transportation Planning Data
Authors: Wilmot Chester G. , Stopher Peter R.
Published: April 2007

The transferability of transportation planning data used to estimate travel-demand models is investigated. It is noted that several traveldemand models can be estimated by using aggregate data, such as trip rates, mode shares, and trip-length frequency distributions. Aggregate data of this type were extracted from the National Personal Transportation Survey of 1995 (NPTS 95) and the North Central Texas Council of Governments Survey of 1996 and compared with those from the Baton Rouge Personal Transportation Survey conducted in 1997. The measures were similar in certain cases and dissimilar in others. Bayesian updating was used to update values from the NPTS 95 survey with values from a small survey conducted in Baton Rouge in 1998. Transferability was marginally improved, although it is expected that the improvement would have been more pronounced if a larger sample of approximately 500 households were available. A panel of 500 households surveyed on an annual basis and used to update transferred data from a variety of sources appears to present a more cost-effective solution to the provision of urban transportation planning data for model estimation than a periodic full travel survey.
Reducing Respondent Burden, Information Processing Effort, and Incomprehensibility in Stated-Preference Surveys: Principles and Properties of the Pairwise Design Strategy
Authors: Wang Donggen , Li Jiukun , Timmermans Harry
Published: April 2007

The validity of stated-preference and choice models is strongly influenced by the ability of the respondents to capture and understand the experimental task, which in turn is a function of the complexity of the attribute profiles and the degree to which the respondents can relate to the choice options. Several measures on respondent burden, information processing effort, and incomprehensibility of stated-preference experiments are developed. The applicability of the measures is demonstrated in a comparison of the pairwise approach with traditional design strategies.
Development of a Prototype Time-Use Diary and Application in Baton Rouge, Louisiana
Authors: Stopher Peter R. , Wilmot Chester G.
Published: April 2007

Over the last 10 years, household travel surveys have evolved from travel or trip diaries to activity diaries and then to time-use diaries. In all previous diaries, whether trip, activity, or time-use, successive trips or activities have been collected in sequence and were assigned a sequence number, beginning with 1. In current research, a time-use diary was developed that collects data on both in-home and out-of-home activities, treats travel as another activity, but gets away from sequential numbering of activities through the day. The new time-use diary is designed to have respondents record their activities by indicating start and end times in a 24-h diary format, similar to ones used in sociological time-use research. The development of the survey instrument through testing and a focus group is described, and a description of the final diary format is provided. Also described are the results of a pilot and main survey in which households were recruited by telephone and then sent diaries in the mail. Completed diaries were returned by mail, with a number of reminder telephone calls made to increase the response rate. The pilot and main survey data are analyzed to show the detail of the activities obtained and the completeness of information that this format of diary produces. The results of this small sample survey are compared with those of a conventional travel diary survey, carried out in Baton Rouge about 2 years earlier, by using telephone recruitment, diary mail out, and computer-aided telephone interview retrieval of diary data. Results, such as the number of trips and activities per household and per person, are compared, as are the sociodemographics of the two samples. It is concluded that the day-planner diary format is a promising format that may provide better reporting of travel and activities than other diary formats.
Assessment of Quick-Refusal and No-Contact Nonresponse in Household Travel Surveys
Authors: Kurth David L. , Coil John L. , Brown Matthew J.
Published: April 2007

Summarized are the procedures and results of a survey used to obtain information on persons in households who quickly refused or could not be contacted to respond to the 1997 Denver Region Travel Behavior Inventory household travel survey. Quick-refusals are people who hang up the telephone without listening to the full short introduction and the first question of the recruiting call. In this study, 1,000 households that quickly refused or could not be contacted in the household survey were sent a letter and a short survey on household demographics in an effort to obtain limited data about the household. To test the impact of a small incentive on the follow-up survey, half the samples were given a $2 cash incentive, and the other half received no incentive. The survey included questions asking why the households did not respond to the survey as well as some limited demographic and travel questions. The results of the survey showed some differences between the nonresponding households and the households that did respond to the household survey. At the same time, the survey results suggested that trip rates for the two groups might be very similar. The results suggest that the hypothesis that quick-refusal and no-contact households travel more than households responding to travel surveys may not be valid.
Elimination of the Travel Diary: Experiment to Derive Trip Purpose from Global Positioning System Travel Data
Authors: Wolf Jean , Guensler Randall , Bachman William
Published: April 2007

Several recent pilot studies combined Global Positioning System (GPS) technology with travel survey data collection to evaluate opportunities for improving the quantity and accuracy of travel data. These studies used GPS to supplement traditional data elements collected in paper or electronic travel diaries. Although many traditional trip elements can be obtained from the GPS data, trip purpose has remained an important element, requiring the use of a diary to continue. Presented are the results of a proof-of-concept study conducted at the Georgia Institute of Technology that examined the feasibility of using GPS data loggers to completely replace, rather than supplement, traditional travel diaries. In this approach, all GPS data collected must be processed so that all essential trip data elements, including trip purpose, are derived. If this processing is done correctly and quickly, then the computer-assisted telephone interview retrieval call could be shortened significantly, reducing both respondent burden and telephone interview times. The study used GPS data loggers to collect travel data in personal vehicles. The GPS data were then processed within a geographic information system (GIS) to derive most of the traditional travel diary elements. These derived data were compared with data recorded on paper diaries by the survey participants and were found to match or exceed the reporting quality of the participants. Most important, this study demonstrated that it is feasible to derive trip purpose from the GPS data by using a spatially accurate and comprehensive GIS.
Temporal and Spatial Variations of Real-Time Traffic Data in Urban Areas
Authors: Stathopoulos A. , Karlaftis M.
Published: April 2007

Variations in traffic flow patterns can be very useful in helping intelligent transportation systems (ITS) provide drivers with useful and accurate route and travel-time information, in examining the potential benefits of flexible work hours, and in assessing the environmental effects of traffic congestion. Much of the work done toward examining temporal and spatial variations in traffic flow has concentrated on freeways, largely ignoring urban areas, where ITS strategies can have the most important effects. Addressed are the issues of temporal and spatial distributions and variations in real-time traffic flow by using data from 140 loop detectors from the greater Athens, Greece, urban area. The results indicate that the temporal distributions of traffic flows are nonnormal, and they vary by direction (toward, in, or away from the central business district) and time of day. This result has important implications in correctly calibrating the real-time simulation models used for volume and travel-time predictions. The results also indicate that traffic in Athens exhibits low seasonality, with lower traffic during the summer months, although traffic conditions are very similar for all weekdays but vary relative to the weekends and by time of day.
Traffic Data Acquisition and Distribution: Archived Data User Services Data Mine
Authors: Dailey Daniel J. , Pond Luke
Published: April 2007

The creation and use of an intelligent transportation systems archived data user services data mine that is available on the World Wide Web are described. The transportation infrastructure in the Seattle metropolitan area is instrumented with thousands of inductance loops. The data from these loops can be used in a variety of modeling and transportation planning activities. However, only with a large repository of this data, covering a significant geographical area and a long temporal period, can complex research and planning questions be posed and answered. Such a repository or data mine is described in terms of the steps necessary to create such a repository, the web interface to use the data mine, the lessons learned in the creation and use of the data mine, the diverse domains from which users have come, and some of the applications for which the data have been used.
Using a Geographic Information System to Track Changes in Spatially Segregated Location Premiums: Alternative Method for Assessing Residential Land Use Impact of Transportation Projects
Authors: Vadali Sharada R. , Sohn Chul
Published: April 2007

The corridor-level impact of a recent major urban highway reconstruction project on residential property values is investigated. The housing market encompassing the North Central Expressway corridor in Dallas, Texas, is examined. Hedonic property price models are estimated for each specific phase of the reconstruction project between 1979 and 1997. Five phases are considered. Geographic information system (GIS) tools, like buffering and geocoding, enable spatial segmentation of property sales and improved model specification facilitated by the creation of different types of proximity variables. An econometric refinement is made to traditional hedonic models that, in conjunction with GIS, allows an examination of spatiotemporal fluctuations in location premiums and property-value trends. The results show that some parts are negatively affected and others are positively affected. This finding is in agreement with the findings of earlier studies. However, this study adds to this conclusion in many ways. The planning process itself mildly affected premiums for those further away. The short-term reconstruction effects are limited to those properties in the immediate vicinity. The results show that the losses in terms of sales discounts during initial phases of construction are made up in the latter phases for those in the immediate vicinity and rebounding property values. The analysis concludes by suggesting that the cost of increased data requirements is outweighed by the informational advantages of the adopted procedure.
Multicriteria Dynamic Segmentation: Geographic Information System Application for Managing Retroreflectivity of Pavement Marking
Authors: Sarasua Wayne A. , Wang Yuchen , Clarke David B. , Singulari Sashank , Korni Ramana M. V. , Zhan Yinghua
Published: April 2007

For many geographic information system applications, such as pavement management and traffic inventories, sections of highway routes may be broken into predefined segments of fixed or variable lengths. The use of fixed-length segments or variable-length segments can present problems in data redundancy or require cumbersome spatial edits when attributes change. Dynamic segmentation was developed to address these problems. Used in conjunction with a milepoint linear-referencing scheme, dynamic segmentation can provide an efficient means for storing varying highway data. However, when dealing with very small segments and constantly changing attributes, the number of segments can make the use of dynamic segmentation slow and cumbersome. Introduced is a multicriteria dynamic segmentation approach that allows on-the-fly segmentlength specification before a linear referenced table is attached to a route. Once the segment length is specified, the attribute data are binned by using database manipulation and aggregation operations based on a user-defined set of criteria. By using binned data, dynamic segmentation speed is enhanced considerably. Small-scale thematic maps of binned data are much more readable, and data spikes can be removed in the binning process. The underlying reference database containing the original small segment attribute data is never compromised in the binning process. The approach was developed specifically to accommodate managing pavement retroreflectivity data in a geographic information system. The system architecture is described, and other types of spatial data that may benefit from this approach are identified.
Public Perceptions of the Midwest’s Pavements: Policies and Thresholds for Pavement Improvement on Rural Two-Lane Highways
Authors: Kuemmel David A. , Robinson Richard K. , Sonntag Ronald C. , Griffin Robert J. , Giese James K.
Published: April 2007

A 5-year, pooled fund study with the Iowa, Minnesota, and Wisconsin departments of transportation assessed the public’s perceptions of pavement improvement strategies and developed thresholds of satisfaction using the departments’ physical indices, such as pavement ride and condition on rural, two-lane highways in the states. Approximately 3,600 drivers in the three states were involved in the three phases of the project, which included 18 focus groups, 400 statewide surveys in each state, and 2,300 targeted surveys across the three states. A multidisciplinary team from Marquette University and a mass media survey lab conducted the studies. A summary of focus group methods and purposes and a three-state summary of policy and improvement issues are provided. More than 450 highway segments were surveyed in Phase III, with input from 2,300 drivers through a two-step recruitment and postdrive interview. Thresholds of International Roughness Index and condition indices are summarized for the three states. The study found a high degree of trust in the three departments of transportation and public support for building longer-lasting pavements and minimizing delay. A three-step methodology is recommended for other state studies. Physical data thresholds using both public satisfaction and the agreement to improve are presented for each state’s physical pavement indices (ride and condition).
Development of a Preventive Maintenance Strategy for Minimizing Roughness-Related Pavement Damage
Authors: Chatti Karim , Lee Doseung
Published: April 2007

The Michigan Department of Transportation (MDOT) uses several measures of pavement performance in managing its pavement network, including the distress index (DI) and the ride quality index (RQI). Currently, decisions on when and where to take rehabilitation or preventive maintenance action are mainly based on the DI. The RQI is used only in a passive or reactive fashion: When DI reaches the threshold for poor ride quality, a decision to rehabilitate the road is made. MDOT is currently funding a research study to develop RQI thresholds for each pavement type (rigid, flexible, or composite) aimed at retarding pavement damage caused by roughness-generated, dynamic (impact) loading. These thresholds correspond to the RQI value at which pavement damage is accelerated by high dynamic loads. Given these new RQI thresholds, extending the service life of the pavement by taking preventive maintenance action in the form of smoothing of the pavement surface (by way of milling, grinding, or adding a thin overlay) becomes possible. New RQI thresholds are proposed in a proactive fashion in the context of preventive maintenance: The objective is to determine the opportune time and locations for applying relatively light maintenance to smooth the pavement surface, thereby minimizing dynamic (impact) loads and extending the pavement service life at minimal cost. For this purpose, a reliability-based model for selecting the optimal timing (or planning period) for such preventive maintenance action was developed using the new RQI-threshold and actual RQI-growth rates from in-service pavements. This model can be an effective tool to use in the context of preventive maintenance of pavements.
Geographic Information System Implementation Plan for Pavement Management Information System: Texas Department of Transportation
Authors: Zhang Zhanmin , Smith Stephen G. , Ronald Hudson W.
Published: April 2007

Integrating a geographic information system (GIS) with an existing pavement management system such as the Texas Department of Transportation Pavement Management Information System is not as simple as merely installing a new piece of software into the existing pavement management system and then operating it. A successful GIS implementation involves not only the information technologies themselves but also other elements, such as personnel and their GIS skills, the organizational structure within which they work, and the institutional relationships that govern the management of information flow. All of these elements need to be managed in an interactive manner. GIS can serve as a platform for integrating various types of data, systems, and technologies. Because of the nature of rapid changes in GIS and related information technology, a well-developed GIS implementation plan is essential. The development of a comprehensive and practical implementation plan using GIS to enhance the pavement management practice in the Texas Department of Transportation is presented. As the basis of the implementation plan, a “three-stage implementation” concept was used to assess the current practice, define the visionary system, and identify the intermediate solutions. Also presented are several key issues and aspects important to the successful implementation of GIS for pavement management.
Implementation of New Highway Management Tools in Developing Countries: A Case Study of Tanzania
Authors: Mushule N. K. , Kerali H. R.
Published: April 2007

In many developing countries like Tanzania, one of the major management problems is the lack of decision-making tools for preparing road maintenance programs. This deficiency results in poor resource allocation and poor utilization of existing assets. This paper summarizes the results of a pilot study on implementing sustainable highway management tools in Tanzania. It was recognized at the beginning of the study that data acquisition is one of the single most expensive items in the implementation of a pavement management system. Consequently a sustainable data acquisition scheme, appropriate to developing countries, was designed and tested. The research showed that using these methods together with appropriate management tools results in better management information. It is envisaged that the methods developed will help Tanzania to determine appropriate resource requirements as well as cost-effective pavement maintenance and rehabilitation programs.
Statistical Data Filtering and Aggregation to Hour Totals of Intelligent Transportation System 30-s and 5-min Vehicle Counts
Authors: Schmoyer Rick , Hu Patricia S. , Goeltz Richard T.
Published: April 2007

For traffic analysts who rely on traditional traffic monitoring data from state and local transportation departments, Intelligent Transportation System (ITS) count, speed, and occupancy data are a largely untapped resource. As with most data, however, ITS data are not immune to outliers, missing values, and other anomalies, which can be time-consuming and costly in data analysis. Furthermore, because ITS data are recorded at intervals as short as 20 s, the tasks of archiving and disseminating them are substantial. Therefore, before ITS data are applied in traditional traffic analysis problems, and before archiving and disseminating them, their fitness for traditional uses should be demonstrated, and methods should be established for ensuring their fitness. Traffic counts from ITS installations in Orlando, Florida, and Long Island, New York were examined. Methods were developed for ( a) filtering out data values beyond credible limits and runs of the same value too long to be credible and ( b) dealing with zeros, which, ambiguously, indicate either missing values or actual zero counts. Because hour totals are often the focus in traditional traffic analyses, methods were also developed for aggregating the remaining counts to estimates of hour totals. Adjustments were made for the joint effect of missing values and trends within hours. Application of the methods to the Florida and Long Island ITS traffic counts and comparisons with hour counts from state departments of transportation demonstrated the feasibility of using ITS counts in traditional traffic analyses.
Fatigue Performance of Piezoelectric Weigh-in-Motion Sensors
Authors: Papagiannakis A. T. , Johnston E. C. , Alavi S.
Published: April 2007

The results of the laboratory evaluation of the fatigue characteristics of the piezoelectric weigh-in-motion sensors of two manufacturers, Vibracoax (VC) and Measurements Specialties Incorporated (MSI), are presented. For each manufacturer, two sensor types were tested, one factory encapsulated and the other bare. The test was conducted in an accelerated fashion using a servo-hydraulic loading system, operated in a loadcontrolled fashion at a frequency of 4 Hz. Three loading conditions were tested: dry under a contact pressure of 860 kPa, wet under a contact pressure of 860 kPa, and dry under a contact pressure of 200 kPa. For each of these loading conditions, a concrete slab was built to allow simultaneous loading of sets of four sensors, one of each of the types evaluated. The results were plotted in the form of voltage output versus the number of load applications. Regression relationships were fitted to the data of maximum voltage versus the number of loading cycles. Under the dry conditions and at 860 kPa contact pressure, the MSI sensors exhibited a decrease in voltage output as the number of loading cycles increased, whereas the VC sensors exhibited an increase in voltage as the number of loading cycles increased. Under wet conditions, the bare sensors of both manufacturers exhibited considerably shorter lives (i.e., voltage output reduced to zero) than the encapsulated ones. No fatigue-related peak voltage changes were found for the sensors under the 200 kPa contact pressure and dry conditions.
Data Collection and Management of the Instrumented Smart Road Flexible Pavement Sections
Authors: Loulizi Amara , Al-Qadi Imad L. , Lahouar Samer , Freeman Thomas E.
Published: April 2007

The flexible pavement research facility at the Virginia Smart Road consists of 12 different designs. All sections are closely monitored through a complex array of sensors located beneath the roadway embedded during construction. The environmental sensors include thermocouples for temperature measurements, time domain reflectometry probes to measure moisture content in the base layers, and resistivity probes to measure frost penetration. The dynamic sensors include pressure cells and strain gauges to measure stresses and strains, respectively, induced at different layers from truck loading. Environmental data are collected daily every 15 min for temperature, every hour for moisture, and every 6 h for frost penetration. Truck testing is performed every week with different loading configurations. The loading variables include three load levels, three wheel inflation pressures, and four different speeds. Data are managed by saving environmental data from different instruments separately using date and section number. Truck loading data are saved by test type (based on loading configuration, inflation pressure, and speed), date of test, and section number. A database is being generated for all 12 sections to study the effect of all tested variables on the different flexible pavement designs. The performance of the used instruments and collected data are presented, and the techniques used to manage the overwhelming data are discussed. In addition, based on instrumentation responses, a preliminary discussion of the load distribution in a tested pavement system, the effect of speed on pavement stress and strain responses, and the effectiveness of drainage layer are discussed.
Design of Route 895 Bridge over James River in Virginia
Authors: Showers Joseph , Kimura Taka , Ryzhikov Victor
Published: April 2007

The Route 895 bridge over the James River in Virginia will be a 1453-m (4,766-ft) long design-build river crossing directly downstream from the Port of Richmond. The highway will have two three-lane roadways in either direction at the James River crossing. East and west approach spans consist of two precast segmental concrete box girders connected by a longitudinal cast-in-place construction joint supported by single circular column piers with hammerhead pier caps. The east approach span segments are erected in cantilever from the piers using ground-based cranes, whereas the west approach is erected using overhead methods because of access limitations beneath the bridge. The main span super-structure will be a two-celled cast-in-place segmental box girder supported by twin-walled piers at the river crossing and single-walled piers at all other locations. The eastbound river crossing span arrangement is 115, 205, and 124 m (377, 672, and 406 ft), and the westbound river crossing spans are 75, 129, 205, and 118 m (246, 423, 672, and 388 ft). Because this was a design-build project, coordination within the design team was a key factor in the project’s success.
Update on Analytical and Experimental Research on Bridge Restrainers
Authors: Vlassis Anastasios G. , Maragakis Emmanuel “Manos” , Saiidi Mehdi “Saiid”
Published: April 2007

Bridge restrainers are used to inhibit relative displacements, prevent unseating of the bridge, and transfer longitudinal seismic forces between adjacent spans at in-span hinges or at hinges between simply supported spans. They have proved to be very effective in earthquakes such as the ones in 1987 at Whittier Narrows, in 1989 at Loma Prieta, and in 1994 at Northridge. Two procedures are currently used to design restrainers in the United States. At the same time, various analytical studies have investigated the dynamic performance of restrainers in the cases of both simply supported and in-span hinges, and several new restrainer design methods have been developed. These studies have shown that although the currently used design methods are conservative in most cases, they neglect many parameters that are important for the response of hinges. Furthermore, new large-scale experimental studies either have been performed or are in the development stage. These studies are expected to enhance the understanding of the complicated phenomenon of hinge response to earthquake excitations. Most of the currently used design methods are presented, and the most recent analytical and experimental studies are discussed.
Long-Term Durability of Structural Composite Lumber in Bridge Applications
Authors: Johnson Eric C. , Yazdani Nur
Published: April 2007

Structural composite lumber (SCL) is a family of newly engineered wood products finding increasing use in highway bridge applications. The advantages of SCL are high strength, flexibility of sizes and shapes, stiffness, and excellent treatability with preservatives. The main concerns in SCL bridge applications are the effects of moisture, exposure to ultraviolet light, and varying temperature and humidity levels on the long-term durability of the bridge members. To document these effects, monitoring of full-scale SCL T-beam bridge members was performed under ambient conditions and an accelerated aging process. A total of 16 beams were monitored under exposed weather conditions with frequent wetting and drying. Variables in the experiment were lumber type (Douglas fir and southern yellow pine), SCL type [laminated veneer lumber (LVL) and parallel strand lumber (PSL)], and preservative type [chromium copper arsenate (CCA) and pentachlorophenol (penta)]. The moisture content of the SCL, ambient temperature, humidity, and the general condition of the beams were monitored. The experiment concluded with the determination of an applicable SCL member for bridge applications. Although most of the members were found to be adequate, a Douglas fir CCA-treated LVL member was found to be the most suitable.
Public Participation and Bridge Type Selection
Authors: Meyer Judy , Barker James M. , Ishmael Ken
Published: April 2007

In 1999 the Ohio Department of Transportation (ODOT) began the final plan development of the Maumee River Crossing Project in Toledo, Ohio. The project involves the engineering, design, and construction of a new high-level bridge crossing over the Maumee River on Interstate 280. It is a signature project for Northwest Ohio and represents the largest and most expensive project undertaken in the history of ODOT. All communities in Northwest Ohio have a history of involvement in public decisions, and a tremendous number of people wanted active participation in design and land use decisions about the new crossing. ODOT recognized the need to balance local and regional interests yet keep the project on schedule. These factors presented unique challenges to the encouragement of public participation at all levels. The agency decided to implement a comprehensive public involvement program that intimately involved the local metropolitan planning organization, ensured that elected officials were apprised of project developments, and provided for regionwide distribution of information about the project. The first major project decision was the selection of the type of bridge to be built. Within 5 months, a decision was made by ODOT, with full community support, to build a concrete cable-stayed bridge over the river. The success of the public involvement program for this segment of the design was found in the ability to focus citizen-based committees on a process for gathering public input and to help the committees understand how to incorporate the input into the bridge type decision.
Effective Use of Public Involvement to Achieve Aesthetic Quality in Bridge Design
Authors: Sherman Mark D.
Published: April 2007

The author relates his personal experience as the project manager in the replacement of four bridges in Columbus, Ohio, that utilized public involvement to achieve aesthetic quality in the bridge designs. The successful use of public involvement in the design process by the Franklin County Engineer’s Office is outlined. Public involvement used as part of the design process has yielded a string of award-winning bridges for the Franklin County Engineer’s Office and has added tremendous civic value to the community. The important aspects of public involvement are identified, and the design process used and the efforts required by the county engineer’s office for the replacement of urban bridges having historical significance or civic importance are outlined. Also illustrated is how engineers are able to maintain control of their projects throughout the design process. Involvement can be an effective tool for designers to achieve higher aesthetic quality in bridge design.
Soil Pressure Measured at Various Fill Heights Above Deeply Buried Thermoplastic Pipe
Authors: Sargand Shad M. , Masada Teruhisa , Schehl Donald J.
Published: April 2007

When a flexible pipe is installed in a dense soil fill, stress redistribution takes place around the pipe because of pipe-soil interaction. The degree of this interaction is considered to be influenced by the stiffness ratio between the pipe and its surrounding soil. Classical theory based on elastic solutions shows that in an ideal installation condition, the zone of the pipe-soil interaction may be confined to one to two pipe diameters from the pipe. In 1999 a research team from the Ohio Research Institute for Transportation and Environment installed a total of 18 instrumented thermoplastic pipes at the deep pipe burial project site in Albany, Ohio. These pipes were placed under either a 6.1-m or 12.2-m (20-ft or 40-ft) embankment fill. During the pipe backfilling and subsequent embankment fill placement, soil pressure cells were placed at different fill heights above selected test pipes to measure the vertical extent of the pipe-soil interaction zone. The field-measured vertical soil pressure compared well with the predictions made by the elastic solutions. Summarized here are the information and data related to the vertical soil pressure measurements made in the Ohio University field study.
Combined Revealed and Stated Preference Nested Logit Access and Mode Choice Model for Multiple Mass Transit Technologies
Authors: Polydoropoulou Amalia , Ben-Akiva Moshe
Published: April 2007

A combined stated preference (SP) and revealed preference nested logit model of access and main mode choice was developed for the Tel Aviv metropolitan area. The data used for model estimation include a conventional travel-activity survey and a customized, computerized SP survey. The model incorporates a generic mass transit alternative that represents any possible combination of existing and new technologies, such as heavy rail, enhanced bus, light rail, and suburban rail. The lower level of the nested logit model represents the access choice to the bus or mass transit alternatives, including walk, park and ride, kiss and ride, and bus access alternatives; the upper level represents the mode choice among bus, mass transit, car driver, and car passenger alternatives. Travel time reliability and seat availability are among the attributes of the public transportation alternatives.
Dynamic Trip Assignment-Simulation Model for Intermodal Transportation Networks
Authors: Abdelghany Khaled F. , Mahmassani Hani S.
Published: April 2007

A dynamic trip assignment-simulation model for urban intermodal transportation networks is presented. The model considers different travel modes, such as private cars, buses, metro-subway, and high-occupancy vehicles. The model captures the interaction between mode choice and traffic assignment under different information provision strategies. It implements a multiobjective assignment procedure in which travelers choose their modes and routes based on a range of evaluation criteria. The model assumes a stochastically diverse set of travelers in terms of their relevant choice criteria and access and response to the supplied information. The model overcomes many of the known limitations of static tools used in current practice. These limitations relate to the types of alternative measures that may be presented and evaluated and to the policy questions that planning agencies are increasingly asked to address.
Assignment Models for Local Truckload Trucking Problems with Stochastic Service Times and Time Window Constraints
Authors: Wang Xiubin , Regan Amelia C.
Published: April 2007

Local truckload trucking plays a major role in the freight transportation industry. In operations in which travel times, loading and unloading times, and waiting times at intermodal and customer facilities are stochastic, deterministic assignment methods can perform poorly. Efficient stochastic assignment models could provide significant benefits. Techniques for developing assignments that explicitly incorporate stochastic elements of the problem have been explored. Several alternative assignment models to take into account both time windows and stochastic service times have been proposed.
Effects of Flow Update Strategies on Implementation of the Frank–Wolfe Algorithm for the Traffic Assignment Problem
Authors: Chen Anthony
Published: April 2007

The Frank–Wolfe (FW) algorithm is the predominant algorithm used to solve traffic assignment problems in transportation planning studies. Despite its slow convergence, it remains the most popular choice among practitioners and researchers. One reason for its popularity is that it requires very modest memory storage, which allows planners to solve networks of realistic sizes. Computer random-access memory storage has become extremely cheap, and it is possible to store more information in the FW algorithm to improve the speed of convergence. This information may be required anyway in certain applications, such as optimal routing in route guidance systems, analysis of environmental impact, nonadditive traffic equilibrium problems, and origin-destination matrix estimation. Different flow update strategies are used to examine how to effectively utilize the additional information to improve the performance of the FW algorithm. Implementation of three flow update strategies in the FW algorithm is discussed. Numerical experiments are performed on four test networks of various sizes.
Assessing Performance Reliability of Road Networks Under Nonrecurrent Congestion
Authors: Yin Yafeng , Ieda Hitoshi
Published: April 2007

Reliability is becoming an increasingly important attribute of road networks. An approach to assess the performance reliability of road networks under nonrecurrent congestion is suggested. Nonrecurrent congestion can arise anywhere along the roadway; when it does arise, it suddenly reduces the capacity of the roadway and makes the traffic condition unstable. Confronted with such uncertain traffic conditions, commuters are known to exhibit different behaviors, namely, risk aversion, risk neutrality, and risk seeking, which are formulated by the expected disutility approach. Commuters are assumed to choose the path with minimal expected disutility. Consequently, a disutility-related multiclass user equilibrium might be achieved when the expected travel disutility between each origin-destination pair can be determined separately and uniquely. Because this disutility implies dissatisfaction or disliking with levels of variations of travel times perceived by commuters, it offers a suitable measure of network reliability for network design. The disutilityrelated multiclass user equilibrium is formulated as a nonlinear complementarity problem, which is a nonadditive path cost problem and can be solved by recently proposed path-based algorithms. Numerical examples are provided to illustrate the application of the proposed approach.
Origin-Destination Matrices Estimated with a Genetic Algorithm from Link Traffic Counts
Authors: Kim Hyunmyung , Baek Seungkirl , Lim Yongtaek
Published: April 2007

Several approaches have been developed to cope with the limits of conventional origin-destination (O-D) trip matrix collecting methods. One is the bilevel programming method, which uses a sensitivity analysis-based (SAB) algorithm to solve a generalized least-squares problem. However, the SAB algorithm has revealed a critical shortcoming when there is a significant difference between the target O-D matrix and the true O-D matrix. This problem stems from the heavy dependence of the SAB algorithm on historical O-D information. Such dependence may lead to a state in which the O-D estimator cannot produce a correct solution, especially when travel patterns are dramatically changed. To avoid the problem of dependency, a robust and stable method is required. A solution method is developed with a genetic algorithm, which is widely used in optimization problems to obtain a global solution. From the results of numerical examples, the proposed algorithm is superior to the SAB algorithm regardless of travel patterns.
Genetic Algorithm for the Time-Dependent Vehicle Routing Problem
Authors: Jung Soojung , Haghani Ali
Published: April 2007

A mathematical model is formulated for the time-dependent vehicle routing problem (TDVRP) and a genetic algorithm (GA) is proposed for solving it. Formulation of the problem considers multiple vehicles with different capacities, pick-up or delivery demands with soft time windows, real-time service requests, and real-time variations in travel times between demand nodes. The objective is to minimize the total cost, which consists of routing cost, fixed cost for using the vehicles, and customer inconvenience costs. A mixed-integer linear programming formulation of the TDVRP is presented. Like other combinatorial problems, to solve the TDVRP exactly, a significant amount of processing time is required. A GA is proposed to solve the problem. The proposed GA was tested on the test problems, and GA results were compared with the exact solutions for small test problems. GA results were also compared with the lower bounds obtained for the solution of the larger problems. In the case of small problems, only 2 of 33 cases have gaps between the GA solutions and the exact solutions, and the maximum gap is less than 5 percent. For larger problems, the maximum gaps between GA solutions and lower bound solutions are less than 7 percent.
Decision Support System for Snow Emergency Vehicle Routing: Algorithms and Application
Authors: Haghani Ali , Qiao Haiying
Published: April 2007

The results of research conducted to develop a decision support system for assisting the Maryland State Highway Administration Office of Maintenance staff in designing snow emergency routes for Calvert County are presented. The research deals with the problem of designing efficient routes for salting trucks in snow emergencies. The task is formulated for mathematical optimization and classified as a capacitated rural postman problem. The capacitated arc routing problem has been shown to be nonpolynomial hard. Several heuristic operations are described, and an algorithm that is a combination of these operations is proposed to solve the real-world snow emergency vehicle routing problems in Calvert County. The results of the implementations indicate that such a system may achieve improvements in service and savings in operational costs.