bluuebunny/crossref_metadata_2025 huggingface dataset:
Bridge Aesthetics: A Discipline in Need of a More Effective Language
Authors: Burke Martin P.
Published: April 2007

A study of bridge aesthetics literature is partially documented. This literature has been and continues to be characterized by jargon and loose, undefined terminology. If the bridge engineering profession is to develop means by which the more routinely successful designers can record their observations and aesthetics advice for posterity in meaningful terms, aesthetics terminology must be changed, defined, and illustrated to such an extent that thought can be given a sharper focus and meanings made clearer. Brief as the documentation is, it nevertheless can help to explain why some papers and significant portions of books and aesthetics design manuals are beyond the comprehension of those for whom the literature was expressly intended. It is hoped that as bridge aesthetics specialists and enthusiasts become more aware of the verbal problems associated with past and present bridge aesthetics writings, concerted efforts can be made to improve aesthetics terminology and eventually achieve a more effective bridge aesthetics language.
Fatigue Analysis and Design of Steel Orthotropic Deck for Bronx-Whitestone Bridge, New York City
Authors: Fanjiang Guang-Nan , Ye Qi , Fernandez Omar N. , Taylor Larry R.
Published: April 2007

A description is given of the parametric study done to evaluate the structural behavior of the replacement steel orthotropic deck planned for the Bronx—Whitestone Bridge in New York City. A principal objective was to analyze the deck details for stress ranges that indicated sensitivity to fatigue cracking. On the basis of the analysis findings, important modifications were made to the preliminary deck design. These changes were primarily to reduce the maximum stresses in the diaphragms and ribs around the diaphragm cutouts—locations that traditionally have been prone to cracking, as observed on orthotropic decks on other bridges. After the completion of the deck design, a full-scale prototype deck measuring 48 by 37 ft was fabricated and subjected to a series of laboratorycontrolled fatigue tests. Proper boundary conditions and loading procedures were created to produce stress ranges similar to those in the full bridge model. Laboratory test results correlated well with the computed stress ranges and demonstrated that the deck had outstanding fatigue resistance and could readily provide the 75-year design service life specified for the orthotropic deck.
Behavior of Steel Bridges Under Superload Permit Vehicles
Authors: Culmo Michael P. , DeWolf John T. , DelGrego Michael R.
Published: April 2007

The need for more power in the United States has spurred a major power plant building program. These plants are usually located where natural gas pipelines cross the power grid, which is generally in more remote areas. To build these plants, construction companies are increasingly using the highway system to move large pieces of plant equipment to the project site. Traditional permit vehicles on highways have had limited gross vehicle weights ranging from 100,000 to 250,000 lb. Special heavyload vehicles have been developed to spread the loads both longitudinally and transversely and to allow engineers to move loads in excess of 1,000,000 lb successfully without the need for temporary support of existing structures. The different types of vehicles that are available and their effect on steel bridges are considered. Simplified methods of analysis including live load distribution, dynamic load allowance (impact), and trailer layout options are investigated. Strain gauge data are presented from an actual 1,000,000-lb permit vehicle that crossed a three-span composite steel bridge in Connecticut. Results of the gauging are compared with the estimates of live load stress from the structural analysis.
Monitoring Prestressed Concrete Box-Beam Bridge for Superloads
Authors: Hag-Elsafi Osman , Kunin Jonathan
Published: April 2007

Monitoring Coeymans Creek Bridge in New York State for superload permit trucks is discussed. The superloads were boiler modules carried on 16-axle trailers, driven by one or two tractor-power units during the bridge crossing. The bridge is an integral abutment structure consisting of 11 prestressed concrete box beams with a composite concrete deck. Approval of the superload permits was based on an engineering analysis that recommended crossing of the bridge in two configurations: the first required that a crabbed trailer be towed across the bridge; the second called for a trailer to be driven in a diagonal crossing fashion. Crabbing, that is, locking trailer wheels to remain parallel to the bridge centerline during the crossing, was recommended for moves of gross weights equal to or exceeding 1,775 kN (400 kips), and diagonal crossings were recommended for those lighter than 1,775 kN (400 kips). The low rating of the structure and the unusually heavy loads motivated the need for investigating actual stress levels in the bridge beams during the superload moves. There was also interest in comparing the two recommended crossing patterns and investigating the level of fixity provided by the integral abutments. The beams were instrumented, and strain data were collected during four of the moves. Analysis of the collected data indicated that the stresses in the beams remained below what would have caused cracking and that, for this bridge, crabbing had no clear benefits over diagonal crossing. The analysis also indicated that the bridge has good transverse load distribution and a significant level of end fixity provided by the integral abutments.
Dynamic Bridge Substructure Condition Assessment with Hilbert-Huang Transform: Simulated Flood and Earthquake Damage to Monitor Structural Health and Security
Authors: Zhang Ray Ruichong , Olson Larry D.
Published: April 2007

Modal vibration tests combined with the Hilbert-Huang transform (HHT) method were used to analyze previous recordings of controlled field-vibration tests of one concrete pile substructure of the Trinity River Relief Bridge No. 4 in Texas in its intact, minor-, and severe-damage states. Piles were excavated and broken to simulate flood and earthquake damage to a bridge substructure. The HHT algorithm is unique in that it reveals the quantitative difference in the instantaneous frequency of sound and damaged structures, consistent with the damage states and with what a simple structural model predicts. This approach differs from traditional modal vibration analyses in that a short-lived shift downward in resonant frequency can be seen in the HHT from a damaged member, whereas this shift is often lost due to the averaging effect of a modal vibration analysis. Accordingly, an HHT-based structural health monitoring procedure is discussed.
Complementary Application of Radar, Impact-Echo, and Ultrasonics for Testing Concrete Structures and Metallic Tendon Ducts
Authors: Maierhofer Christiane , Krause Martin , Mielentz Frank , Streicher Doreen , Milmann Boris , Gardei Andre , Kohl Christoph , Wiggenhauser Herbert
Published: April 2007

Nondestructive testing of concrete structures plays an increasing role in civil engineering, although until now the full potential of such techniques has not been tapped. For posttensioned structures, the investigation of tendon ducts is one of the most essential testing problems. The location of tendon ducts, the determination of concrete cover and, especially, the detection and quantification of ungrouted areas inside the ducts are the relevant questions. Recent developments and opportunities of radar, impact-echo, and ultrasonics for the investigation of tendon ducts are presented. Although the obtained results on positioning and concrete cover determination are sufficient, the location of ungrouted areas is still a matter of research. Thus, new approaches for this testing problem have to be considered. Additionally, the combined use of complementary techniques offers a high potential to increase the reliability of results. Data will be displayed on the combined application of acoustic and electromagnetic impulse-echo methods and of data fusion related to the investigation of tendon ducts.
Seismic Retrofit of Flared Reinforced Concrete Columns in Multispan Viaduct: From Research to Field Implementation
Authors: Saiidi M. Saiidi , Mangoba Nathaniel
Published: April 2007

Following the failure of the flared column in the Mission Gothic Overpass during the Northridge Earthquake, a multiphase study of flared bridge columns in northern Nevada was undertaken. The study, the field implementation, and a cost-benefit analysis for a 16-span viaduct are summarized. The study included analytical evaluation of the piers in addition to quasistatic and shake table testing of large-scale as-built and retrofitted columns. The jacket material included steel, glass-fiber composites, and carbon-fiber composites. Results showed that shear retrofit provided sufficient displacement ductility capacity even though the confinement requirements were not met. All three jacket materials were found to be satisfactory. Because the space under the bridge was used for offices and garages and because the working space around many of the columns was limited, composite fabrics were selected for field implementation. Because the columns were flared and nonprismatic, a continuous wrap could not have been applied efficiently. A new method of composite installation was devised in the course of research and was used in the field. As a result of the research, less than one-third of the columns were found to be in need of retrofit. The cost-benefit analysis of the selected retrofit indicated a 64% saving over the cost of conventional column retrofit.
Decision Aids for Tunneling: Update
Authors: Einstein H. H.
Published: April 2007

Decision aids for tunneling (DAT), a computer-based tool, are used to determine tunnel construction cost and time as well as other information related to tunnel construction. Most important, the DAT allow uncertainties to be considered, an essential aspect in modern project and construction management. A brief overview of the DAT and of a variety of applications is first provided to (re)familiarize the reader. Emphasis is then placed on two recent DAT applications, namely, updating and resource management. Updating uses information collected during construction to reduce uncertainties. The resource management application shown here deals with reuse of muck to produce concrete. These practical cases reemphasize the wide variety of applications that can benefit from the use of the DAT.
Predicting Tunneling-Induced Ground Movement
Authors: Laefer Debra F. , Kim Wan Soo
Published: April 2007

Cost-effective and permissible tunneling can occur only if ground movement prediction is refined to accommodate changes in both the urban environment and tunneling technology. As cities age, tunnels are being installed closer to existing structures and in increasingly complicated belowground conditions. The reality of stacked tunnels, abandoned facilities, and more extensive use of underground space raises the question of whether relationships derived for single open-shield tunnels in free-field conditions can adequately predict ground movement for modern tunneling techniques with more complicated site conditions. Traditional empirical methods to predict maximum surface settlements and the percentage of lost ground for paired tunnels of the new Austrian tunneling method (NATM) in noncohesive soils are evaluated. Predictive data are compared with field measurements for grouted and nongrouted sections. Results showed that the estimated maximum settlement values of an NATM tunnel were highly similar to those of an open shield tunnel for both the grouted and ungrouted sections, although in some cases the Gaussian shape significantly underestimated the depth of the settlement trough in the outer 30% to 40%. Grouting substantially altered the amount of settlement. The average percentage of volume of lost ground with grouting was 1.6%, whereas the value was 5.2% where no grouting occurred. The empirical methods typically generated a fairly reasonable set of responses for an NATM tunnel.
Strengthening Steel Structures and Bridges with High-Modulus Carbon Fiber-Reinforced Polymers Resin Selection and Scaled Monopole Behavior
Authors: Schnerch David , Stanford Kirk , Sumner Emmett A. , Rizkalla Sami
Published: April 2007

Cost-effective solutions for the rehabilitation and strengthening of steel structures, including bridges and monopole towers, are greatly needed. Rehabilitation is often required because of cross-section losses occurring as a result of corrosion; strengthening may also be required because of changes in the use of a structure. Current techniques for strengthening steel structures have several drawbacks, including their fatigue performance and the need for ongoing maintenance owing to continued corrosion attack. The current research program makes use of a high-modulus carbon fiber for the strengthening of steel structures. This program, currently in progress, includes phases for the resin and adhesive selection for wet layup of carbon fiber sheets and bonding of precured laminate plates. Test results of the first scaled monopole tower showed a 25% increase in stiffness in the elastic range compared with the same monopole before strengthening.
Hybrid Bridge Strengthening Structural Rehabilitation of Blue Heron Bridge, West Palm Beach, Florida
Authors: Shahawy Mohsen , Okeil Ayman M.
Published: April 2007

The bridge located on Blue Heron Boulevard over I-95 in West Palm Beach, Florida, was damaged when a construction vehicle carrying a large crane violated the height clearance limitation. The collision caused extensive damage to two of the bridge girders (AASHTO Type II), which led to the closure of one lane on I-95. Details of the structural rehabilitation of the bridge are presented. A strengthening scheme was devised for the bridge rehabilitation. The need to reopen the closed lane in a short period of time required a hybrid strengthening alternative, in which the first damaged girder was fully replaced with a new steel girder and the second girder was strengthened with composite Iaminates. A load-rating study showed that the strengthening scheme raised rating factors to acceptable levels for all Florida Department of Transportation standard trucks.
Strength Prediction by Using Maturity for Portland Cement Concrete Pavement Construction at Airfields
Authors: Rasmussen Robert Otto , Cable James K. , Turner Dennis J. , Voigt Gerald F.
Published: April 2007

A recent demonstration of a noncomplex solution for monitoring concrete strengths in real time used concrete maturity technology. During a recent airfield concrete pavement construction project in Des Moines, Iowa, several commercially available maturity measurement devices were evaluated along with an innovative strength assessment and prediction system, Total Environmental Management for Paving. This field evaluation demonstrated that current maturity technology could be used to assess the strength of a concrete airfield pavement successfully in real time. Furthermore, the adoption of maturity-based technologies can expedite airfield repair and construction and can expand the knowledge of concrete pavement as it is placed.
Roller-Compacted Concrete Mix Design Procedure with Gyratory Compactor
Authors: Amer Nader , Storey Chris , Delatte Norbert
Published: April 2007

Roller-compacted concrete (RCC) pavements are durable and can be built rapidly and economically. In previous research, the gyratory compactor has proved to be a reliable instrument and overcome the drawbacks of other methods used to mold laboratory and field samples. Work is under way by different organizations in Canada, Japan, and the United States to improve mix design procedures for RCC. One procedure widely used for RCC pavements was developed by the U.S. Army Corps of Engineers. This research investigated improving mixture proportioning of RCC by using a gyratory compactor. Previous research suggested that the gyratory compactor could be used effectively to produce RCC test samples for both compressive and splitting tensile strength. An RCC mix design procedure using the gyratory compactor can benefit many transportation agencies because it provides a reliable way to evaluate the strength and density of RCC mix designs. Results for several RCC mixtures compacted to different densities are presented, along with comparisons with modified Proctor test results. Using the gyratory compactor to design better RCC mixtures might lower the costs and improve the reliability of RCC pavements.
Modeling Timing and Duration of Activities and Trips in Response to Road-Pricing Policies
Authors: Ettema Dick , Ashiru Olu , Polak John W.
Published: April 2007

A model of timing and duration of activities and travel is outlined. The model assumes that marginal utility derived from activities encompasses two distinct components, one derived from duration of activity involvement and the other derived from activity participation at a particular time of day. To test travelers' responses to road-pricing schemes, an operational model is developed and calibrated on a stated-preference data set collected in a previous study in London. The estimation results suggest that utility derived from work is partly duration dependent and partly time-of-day dependent. A model in which the duration-dependent marginal utility is described by a logarithmic function and the time-of-day-dependent marginal utility is described by a Cauchy function provides the best description of trip and activity timing. The model is used to evaluate the effect of various pricing schemes for the estimation sample. The predictions suggest that pricing policies have a considerable impact on commuters' trip and activity scheduling, involving shifts to earlier and later departure times. Also discussed are the implications of the model for value-of-time estimates. The results indicate that the value of time changes through the day depending on the utility profiles of the activities.
Relationship Between Occupational, Industrial, and Sociodemographic Characteristics and Job Start Times: Evidence from Current Population Survey
Authors: Sinha Avinash K. , Thakuriah Piyushimita (Vonu)
Published: April 2007

Alternative work arrangements and unconventional shift schedules are increasingly becoming a part of the economy. Temporal mismatch problems occur when individuals who are traditionally transit dependent do not have access to potential job locations during off-peak times. The Current Population Survey is used to examine the relationships between job start times and a set of Sociodemographic, occupational, and industrial characteristics. A binary response variable, conventional and unconventional start times, gives preliminary insight into the nature of these relationships. A detailed multinomial logit model gives more in-depth insight by analyzing the discrete choice of job start times during unconventional hours, such as the p.m. hours, night hours, or midday, relative to a baseline daytime shift. In addition, probabilities of working in jobs with alternative start times are developed for a set of hypothetical workers with key sociodemographic profiles. It is concluded that workers are self-selected into certain occupations in specific industries by their skills, education, and other workforce factors. The nature of jobs has implications for work schedules and alternative work arrangements. The ability to select certain schedules and the work arrangement of choice therefore is conditional on being employed in those types of jobs. Thus, there appears to be some type of simultaneity between the type of occupation and work schedules. It appears that policies to address the temporal mismatch problem are partly an issue of workforce development (so that workers can seek jobs in more work-arrangement-friendly occupations) and partly a transportation problem.
Improving Performance of Multiagent Rule-Based Model for Activity Pattern Decisions with Bayesian Networks
Authors: Janssens Davy , Wets Geert , Brijs Tom , Vanhoof Koen , Arentze Theo , Timmermans Harry
Published: April 2007

Several activity-based models are now becoming operational and are entering the stage of application in transport planning. Some of these models use a set of decision trees to support decision making instead of using principles of utility maximization. However, it is believed that the structure of decision trees can sometimes be very unstable and sensitive to highly correlated predictors. Therefore, this study examines whether decision trees constitute the best representational form to capture the behavioral mechanisms and principles that individuals and households use to organize their activities. Findings are reported from experiments conducted by means of Bayesian networks to gain a better understanding of the predictive performance of Albatross, a sequential rule-based model of activity-scheduling behavior. The performances of Bayesian networks and decision trees are compared and results are evaluated by means of detailed quantitative and qualitative analyses. The results showed that Bayesian networks outperformed the decision-tree-based approach for all decision agents of the Albatross model. Given this excellent performance, it is believed that the research community may potentially consider the use of Bayesian networks in developing activity-based transportation models.
Utility of Schedules: Theoretical Model of Departure-Time Choice and Activity-Time Allocation with Application to Individual Activity Schedules
Authors: Ashiru Olu , Polak John W. , Noland Robert B.
Published: April 2007

The timing and duration of activities are important components of individual travel and activity behavior, affecting spatial interaction and mode choice decisions, highway and transit congestion, accessibility, and the general degree of social exclusion or inclusion experienced by the individual. The choices of timing and duration of activities are closely interrelated; however, few researchers have attempted to study this relationship. Instead strong separability assumptions have been made concerning the timing and duration dimensions. A utility theoretical model of joint activity-timing and duration choice is presented that addresses a number of the limitations of existing scheduling and time allocation models. How the theoretical model can be used to provide insight into the nature of the activity-scheduling process is outlined, and an algorithm is presented that can be used to operationalize the time allocation and activity-scheduling model. An estimable empirical form of the theoretical model is subsequently developed in which it is acknowledged that past and present activity and travel behavior decisions affect both existing and expected behavioral outcomes. How the model can be used to develop a number of disaggregate, activity-based accessibility measures is outlined, and with the aid of a simple hypothetical case study, a number of behavioral characteristics of the time-allocation and activity-scheduling model are demonstrated.
Weekend Activity and Travel Behavior in a Developing Country: Empirical Study Using Multilevel Structural Equation Models
Authors: Jin Kim Hyung , Hoon Kim Dea , Chung Jin-Hyuk
Published: April 2007

According to the government of the Republic of Korea, by 2010 workers throughout the country will have a 5-day workweek instead of the current 6-day one. The change will have a great impact on the lifestyles of the employed and their families and also on the transportation system, since travel patterns, traffic demand, and the patterns of congestion will change during the weekends. Before the policy becomes effective, negative impacts on the transportation system should be examined to conceive measures that will maintain a dependable level of service during the weekends. So far, however, little attention has been directed to the understanding of how policies affect travel behavior in Korea. In this study, activity participation and travel behavior are compared between two population groups, those currently working 5 days a week and those working 6 days a week. Understanding the difference is an essential component of the development of this policy in Korea, especially since the 5-day workweek will be instituted in the near future. The data set used in this study is the Seoul Metropolitan Area Transportation Survey, which was conducted in June 2002. Multilevel structural equation models (SEMs) are developed, which combine features of SEMs and multilevel analysis. The SEM makes possible the estimation of complex relationships among exogenous and endogenous variables, and multilevel analysis can interpret interdependency among hierarchical structural levels such as those within and between household levels simultaneously. With this approach, significant relationships were found among sociodemographics, activity participation, and travel behavior within households as well as between household models, captured simultaneously by the multilevel SEMs employed in this research.
Travel Mode Choice of the Elderly: Effects of Personal, Household, Neighborhood, and Trip Characteristics
Authors: Kim Sungyop , Ulfarsson Gudmundur F.
Published: April 2007

The travel patterns and travel mode choice of the elderly are analyzed. The elderly are here defined as those who are both 65 or older and retired. A rapid increase in the older population and their proportion in society has tremendous implications for transportation planning and the policy arena. Previous studies on mode choice have been largely focused on working-age people, and existing studies on the travel mode choice of the elderly are limited to descriptive analyses. A systematic analysis is presented of the mode choice of the elderly and how it relates to activity purpose. It is found that neighborhood and trip characteristics, as well as personal and household characteristics, are associated with the mode choice of this group. For example, the elderly are more likely to use transit if they live within five blocks of a bus stop, and they are more likely to share a ride with others when chaining trips, doing errands, or going to a medical appointment and are less likely to use transit when going shopping or doing errands. The elderly prefer walking when going on recreational or personal trips. Those with a higher income are more likely to drive or carpool. The results shed light on the mode choice of the elderly and contribute to the development of a transportation policy framework that considers the elderly. The results suggest that transportation strategies must move beyond private automobiles to prepare adequately for the increasing number of the elderly in society and their mobility needs.
Transportation Network Evacuation Planning with Household Activity Interactions
Authors: Murray-Tuite Pamela M. , Mahmassani Hani S.
Published: April 2007

An evacuation model that explicitly accounts for observed household interactions is presented. A series of linear integer programs determines household decisions of where its members will meet and how to organize the meeting logistics in the event of an evacuation. In the first mathematical program, the household selects a meeting location. In the second, the household members without vehicles are assigned to drivers. This second formulation results in an activity chain for each driver. These chains are then loaded onto the network using a microassignment simulation procedure that captures the resulting traffic interactions taking place in the network. An example is presented to illustrate the methodology; a network serving three business, six residential, and five school zones is examined. An evacuation during business hours is simulated using the activity chains for 20,000 households. Comparison of clearance times with different network loading strategies reveals that a minimum of 150% of the original demand should be used for evacuation planning purposes if no special considerations or adjustments to the network model are made. Modifying the network to account for unusual parking circumstances that may arise when parents pick up their children at school under emergency conditions may allow for a reduction in the amount of demand required for evacuation planning. The exact multiplicative factor depends on the loading scenario employed by the planning agency and any additional special emergency considerations that may be taken into account.
Home-Based Teleshoppers and Shopping Travel: Do Teleshoppers Travel Less?
Authors: Ferrell Christopher E.
Published: April 2007

Some have assumed that teleshopping will become a functional substitute for traditional retail shopping and thereby reduce physical shopping trips and vehicle miles traveled. More recent studies have painted a far more complex picture, in which a combination of lifestyle, shopping opportunities, and the costs of travel all play a role in a person's choice of shopping modes. In this study, data from an activity-diary survey collected by the Metropolitan Transportation Commission, California, were analyzed to gain insights into the degree to which teleshopping substitutes for traditional out-of-home shopping trips, person miles traveled for shopping, and shopping-trip chains. A two-step linear regression model was used to estimate the effects of home-based teleshopping. Results indicate that teleshopping households engage in more shopping trips and chain more of their shopping trips. It is hypothesized that teleshopping has a complementary effect on out-of-home shopping and leads to more shopping trip making and that the time for these additional trips and home teleshopping activities is enabled through efficiencies gained from increased trip chaining. Time saved through increased trip chaining and teleshopping may provide the additional time needed to shop more—both from within the home and outside the home.
Growth Visioning for the Westside Cities of Los Angeles County, California: Land Use and Transportation Factors Influencing Congestion and Jobs-Housing Imbalances
Authors: Singa Krute , Hutabarat Ria , Chou Mary
Published: April 2007

Sprawl is a significant concern in southern California, where continuous growth on undeveloped land contributes to heavy congestion, poor air quality, long travel times, and costly infrastructure development. By 2030, the Southern California Association of Governments (SCAG) anticipates an additional 6 million people living in the six-county region of Los Angeles, Riverside, Ventura, San Bernardino, Imperial, and Orange Counties. To plan for this growth in a way that does not deteriorate the region's quality of life, SCAG is working with its 14 subregions on a growth visioning project called the Southern California Compass. Complementary growth visioning efforts have been conducted by SCAG subregions including the westside cities of Beverly Hills, Culver City, Santa Monica, West Hollywood, and a number of unincorporated communities in western Los Angeles County. This study describes the westside cities' growth visioning project and focuses on performance measures, community aspirations, and strategies to accommodate projected growth in a manner specific to the subregion. Performance measures developed with population, household, and employment projections revealed a high jobs-housing ratio and high inbound and outbound commuter traffic levels. Projected growth scenarios will further strain housing, transportation, and community services. Information from performance measures and community input was combined to identify policy options to potentially accommodate growth in the westside cities subregion, in line with the SCAG growth visioning principles of mobility, livability, prosperity, and sustainability.
Estimating Effect of Time-Related Factors on Transit Use with a Large-Scale Mobility Survey and Transit Information
Authors: Vande Walle Stefaan , Steenberghen Therese
Published: April 2007

There is a strong interest among policy makers in measures intended to rationalize private car use. However, this requires prior assessment of the likely impact on car and public transport demand associated with each policy option. For example, what is the likely effect of a reduction of travel time by public transport on mode choice? Such effects can be quantified as elasticities, defining the percentage change in a response variable to a 1% change in an independent variable. The aim of this study is to provide a quantitative overview of the impact of travel time, its components, and its derivatives on transit demand. Data were used from a Belgian mobility survey that was supplemented with a database with a calculated public transport trip for each trip in the mobility survey, with the use of search engines and timetables from the public transport companies. Various functional models were applied to derive demand elasticities. An evaluation of these calculated travel times with public transport search engines shows considerable but reasonable differences with observed trips. Travel time ratios, comparing car and transit travel times, and generalized time estimations, weighting walking and waiting times, offer the best approach to identify the relation between travel time and transit use and result in strongly negative elasticities, particularly when captive travelers are separated. The study contributes to the discussion on the effect of travel time on public transport demand not by using a transport model but by using a survey and transit timetable information.
Chicago, Illinois, Smart Growth Study
Authors: Shimizu Ronald , DeBacker Mary , Hubbard Donald , Stitt Susan , Blankenhorn Randall
Published: April 2007

As part of the state's balanced growth initiative, the Illinois Department of Transportation initiated a smart growth study designed to assist mature urban communities located on the North Side of Chicago and the near northern suburbs in addressing traffic, pedestrian, bicycle, and transit issues and to build an understanding of the land use-transportation relationship. One of the major goals of this study was to demonstrate how an interactive, multijurisdictional planning process could address common land use and transportation issues with smart growth principles. A four-phase approach was developed. Phase 1 resulted in building an understanding of the physical, economic, and political dynamics of the study area and a strategic assessment of opportunities and constraints for promoting smart growth, land use, and transportation principles. Phase 2 included a community workshop with breakout groups to discuss specific transportation and land use issues. With input from the workshop and the study advisory group, a set of case studies was identified. These case studies were performed in Phase 3. Six site-specific case studies were performed that examined possible solutions with balanced growth principles. Three programmatic case studies were performed that included traffic-calming program guidelines, a context-sensitive roadway functional classification, and transit station area zoning guidelines. A funding source guide was also developed. The final phase was the development of a toolbox that included a comprehensive set of smart growth techniques. The study results were compiled on a compact disc and distributed to local communities.
Assessing Safety Impacts of Long-Range Plans in Small and Medium-Sized Communities
Authors: Schwetz Thomas B. , Reiff Bud , Chatterjee Arun
Published: April 2007

In updating the regional transportation plan for the Eugene-Springfield area in Oregon, the Lane Council of Governments (LCOG) developed a series of six alternative plan scenarios to test the effectiveness of various strategies (transportation demand management, land use, system changes). To measure the effectiveness of scenarios performance criteria were developed. While safety was a broad issue of interest to policy makers and the public, no safety criterion was found that could be modeled and forecasted in a practical manner. In 2001, a research project was undertaken by the University of Tennessee to develop and test practical tools for assessing safety impacts of transportation plans for urban areas. As part of this research, LCOG was engaged to apply a set of accident rates to its alternative long-range plan scenarios. This study concludes that, in general, at the point where issues raised as part of this application are addressed through future research, the approach of using a standard travel-demand forecasting model and a series of crash forecasting spreadsheets could provide a practical means for assessing the safety impacts of long-range plans in small and medium-sized communities. The application effort yielded several specific observations relevant to future efforts. Key issues include lack of transferability of crash data, availability of and easy access to detailed crash data for a given urban area, refinement of continuous functions for developing crash forecasts, and refinement of intersection crash analysis methods.
Corridor Preservation: Best Practices for Local Governments
Authors: Williams Kristine M. , Frey Robert
Published: April 2007

Corridor preservation is an issue of growing concern. The costs of providing transportation infrastructure are escalating, particularly in growing urbanized areas. Right-of-way (ROW) costs often represent the single largest expenditure for a transportation improvement. ROW becomes so costly that jurisdictions are unable to provide needed transportation infrastructure, the existing system will fail to function as planned, and quality of life will suffer. It is critical for local governments to work within their authority to ensure that land for future transportation facilities is preserved as development occurs. Better coordination of land use and transportation decisions will result in a variety of benefits, including earlier public notification of the ROW needs for planned road improvements, less need to relocate homes or businesses when improvements are made, and less damage to existing sites when the land is acquired. Many jurisdictions have some method of ROW preservation, but most lack a systematic program for preserving ROW and managing access. Those that have succeeded have assembled a variety of tools they can mix and match to the circumstances at hand. No single method works for all situations or is legally available in every state. The following measures can help ensure a more successful program: develop a long-range transportation plan with broad community support, set clear priorities and complete projects on time, establish an advance acquisition funding source, establish a systematic program of policies and regulations, and provide a range of mitigation measures to address potential hardships and preserve property rights.
Identifying Opportunities for Intelligent Transportation Systems Applications in California's National Parks: Project Overview and Summary of Recommendations
Authors: Strong Christopher , Eidswick Jaime , Turner Shawn
Published: April 2007

A research project was conducted that sought to understand the transportation needs within California national parks by looking at two case study parks: Golden Gate National Recreation Area and Sequoia and Kings Canyon National Parks. After transportation needs for these parks were identified through outreach meetings and visitor surveys, potential intelligent transportation system (ITS) solutions or themes were recommended along with how to follow national guidelines for planning and implementing these themes and solutions. This study also includes solutions and themes that were not identified for the two case study parks but that show promise for other California parks. The goal of this project is to help managers of any park in California to identify and implement ITS solutions and themes that can help to address their park's specific transportation needs.
Tourism Business and Intelligent Transportation Systems: Acadia National Park, Maine
Authors: Zimmerman Carol A. , Daigle John , Pol James
Published: April 2007

A suite of intelligent transportation system (ITS) technologies was deployed as part of the Acadia National Park (Maine) field operational test (FOT). This study evaluated the FOT that took place in 2002 and focused on the experience of the managers of businesses in the gateway communities near the park. The ITS FOT was intended to test the effectiveness of ITS for addressing the transportation problems that had the potential to negatively affect visitor experience at the park and in turn the tourism industry upon which the region depends. A survey of 257 business managers presents their views on transportation problems in the area, attitudes toward the Island Explorer bus service, and reactions to ITS. The results indicate that managers perceive many benefits of ITS to visitors. They also see general economic benefits from ITS but are more neutral about direct effects to their own businesses. Finally, a surprisingly negative reaction from the business community to Acadia traveler information on the new Maine 511 telephone service illustrates the challenge of marrying the interests of the business community with those of travelers.
Measuring Congestion: Learning from Operational Data
Authors: Bremmer Daniela , Cotton Keith C. , Cotey Dan , Prestrud Charles E. , Westby Gary
Published: April 2007

As transportation agencies develop operations-based approaches to congestion management and carefully weigh system investments in operations as well as capital improvements, new types of performance information and communication are clearly needed. Citizens expect action on traffic congestion and demand performance information that relates to their concerns and is easy to understand. Traditional congestion measurements are based on modeled speed estimates generated from volume and capacity information. They are difficult to communicate, fail to capture subtle changes in real-world system performance, and are inadequate for many aspects of evaluating specific impacts of projects on congestion. The Washington State Department of Transportation (WSDOT), like other transportation agencies, has been grappling with new approaches to using operational data to monitor and measure system performance. This study describes progress the agency has made to date and how this work ties into national efforts. Speed and travel time data derived from the loop detector network on Puget Sound urban freeways are used by WSDOT to measure and communicate realtime travel times on 12 major commute routes. Continued work toward analyzing different types of congestion distinguishes between recurrent congestion caused by inadequate capacity and nonrecurrent congestion caused by incidents, inclement weather, and other factors such as travel to and from major sporting events. The agency also has made progress in measuring what is of most concern to commuters and haulers: travel time reliability.
Using Long-Term Pavement Performance Data to Predict Seasonal Variation in Asphalt Concrete Modulus
Authors: Salem Hassan M. , Bayomy Fouad M. , Al-Taher Metwally G. , Genc Ismail H.
Published: April 2007

The seasonal variation of the asphalt concrete (AC) modulus with changes in pavement temperature is discussed. The main goals of the research was to develop (a) regression models that enable design engineers to assess seasonal changes in AC modulus and (b) an algorithm for calculating a seasonal adjustment factor (SAF) that allows estimating AC modulus in any season from a known reference value. The study is based on analyzing data collected at Long-Term Pavement Performance (LTPP) program sites in both freezing and nonfreezing zones. The data were obtained from the LTPP database in the DataPave 3.0 software. The approach adopted in this study was to select LTPP-seasonal monitoring program sites that represent various climatic regions and use the backcalculated modulus and pavement temperature data to develop regression models for the modulus-temperature relationships for various sites in both freezing and nonfreezing zones. Two regression models were developed to relate the variation in modulus with the variation in pavement temperatures in various seasons for both freezing and non-freezing zones. These models incorporate AC layer properties such as thickness, bulk specific gravity, air voids, and asphalt binder grade. A model for determining the SAF was also developed.
A 9-Year Evaluation of Field Cracking and Rutting Performance of SPS-9 Superpave Experiment
Authors: Kavanagh Leonnie N.
Published: April 2007

Though the first of 26 Specific Pavement Study 9 (SPS-9) experiments was built more than 9 years ago to assess the field performance of the Superpave® asphalt and mix design and analysis system, there has been no definitive report on the experiment's overall field performance. This analysis therefore evaluates the performance of the SPS-9 experiments through the use of the 2001 distress data available from the Long-Term Pavement Performance information management system database. Field distresses evaluated in this study included rutting, fatigue cracking, longitudinal wheelpath and nonwheelpath cracking, and transverse cracking. In addition to the field distress evaluation, a statistical analysis was conducted to determine whether a performance difference exists between the Superpave "correct" performance-graded (PG) binder section and the Superpave alternative PG binder section designed to exhibit early distress at each of the SPS-9 sites. The statistical analysis relates the distresses through means ( t-test) and variances ( F-test). The data analysis indicates that more than 78% of the Superpave sections have no cracking and more than 80% have only nominal rutting. When cracking occurred, fatigue and longitudinal nonwheelpath cracking were the predominant distresses. For the Superpave binder sections, distresses began to appear within 4 years of construction, with overlays outperforming new pavements and agency sections performing as well as or better than Superpave sections. Surprisingly, the results of the t-test and the F-test analysis showed no statistical difference (at the 95% confidence level) in the fatigue cracking, longitudinal wheelpath cracking, longitudinal nonwheelpath cracking, and rutting distresses between the Superpave binder sections and the Superpave alternative binder sections. However, a statistical difference (based on the F-test) existed for transverse cracking performance between the two PG binder sections.
Tire-Induced Surface Stresses in Flexible Pavements
Authors: Soon See-Chew , Drescher Andrew , Stolarski Henryk K.
Published: April 2007

Site observations of flexible-pavement distress in various countries indicate frequent occurrence of longitudinal cracking in the top asphalt concrete layer. Analytic and numerical studies of multilayer elastic systems subject to wheel loads have linked longitudinal cracking to surface tensile stresses. However, due to the complexity of tire-pavement interaction resulting from tire geometry and loading conditions, accurate and fully representative distribution of surface stresses remains partly unknown. An attempt is made to provide information on surface stresses that derives from both theory and experiments. In particular, contact mechanics solutions are analyzed to gain information on loads that are subsequently used in performing numerical evaluation of surface stresses. Examples of three-dimensional computations using the finite-element code ABAQUS illustrate the analysis. The results indicate a greater potential for tensile stresses outside the tire treads than in the middle of the treads.