bluuebunny/crossref_metadata_2025 huggingface dataset:
Wood in Transportation Program: An Overview
Authors: Duwadi Sheila Rimal , Ritter Michael A. , Cesa Edward
Published: April 2007

Research and demonstration bridge projects to further develop wood for transportation structures increased substantially in the United States in 1988 under a legislative action by the U.S. Congress known as the Timber Bridge Initiative. This program, renamed the Wood in Transportation Program, continues today and is administered by the Forest Service. FHWA became involved in timber bridge research in 1990. The FHWA program increased substantially under the Intermodal Surface Transportation Efficiency Act of 1991 (ISTEA). From 1992 to 1997, ISTEA authorized significant funding for timber bridge research, technology transfer, and demonstration bridges. The current transportation authorization, the Transportation Equity Act for the 21st century, does not contain a program for timber bridges similar to that of ISTEA; however, there are provisions under the fiscal year 1999 Transportation Appropriations Bill for advancing engineered wood and composites technology through research and demonstration projects to further develop the use of wood for transportation structures. As a result of these combined efforts, a large number of research projects have been initiated, and a number of demonstration bridges have been built under both programs. An overview of the research and the demonstration timber bridge programs is provided here.
Optimal Network-Level Bridge Maintenance Planning Based on Minimum Expected Cost
Authors: Frangopol Dan M. , Gharaibeh Emhaidy S. , Kong Jung S. , Miyake Masaru
Published: April 2007

The goal of bridge management is to determine and implement the best possible strategy that ensures an adequate level of safety at the lowest possible life-cycle cost. Although this is generally recognized, the integration of life-cycle cost analysis with bridge reliability analysis has been very limited. Moreover, this has been formulated and illustrated only for individual bridges. A framework for optimal network-level bridge maintenance planning based on minimum expected cost is presented. The goal is the minimization of the expected maintenance cost of a bridge stock with maintenance of the lifetime reliability of each bridge above an acceptable (target) level. The approach is illustrated for a stock of realistic highway bridges. Individual bridges in this stock have different ages, and their reliabilities are time dependent. The framework offers a rational basis for optimizing the resource allocation for management of a stock of gradually deteriorating bridges based on balancing life-cycle maintenance cost and lifetime reliability. This has important practical implications in the development of the optimal management strategy for the bridge stock.
Testing Bridges by Using Tiltmeter Measurements
Authors: Sanli Ahmet K. , Uzgider Erdogan A. , Caglayan Ozden B. , Ozakgul Kadir , Bien Jan
Published: April 2007

An efficient numerical procedure based on the cubic spline technique is developed to obtain the vertical displacements of the bridge deck using the slope values measured at selected points under the test loading. Most static load tests of bridges are performed to evaluate the stiffness characteristics of bridge structures or to check the accuracy of their computer models. From this standpoint, vertical displacements of the bridge under certain loads have a crucial importance. However, if the bridge is over a river, a lake, muddy ground, or a major highway, conventional displacement transducers cannot be used appropriately for this purpose. Furthermore, strong wind and the bridge’s height badly affect the accuracy of the transducers. Another way to obtain bridge deflection is to use an indirect method. Tiltmeters, which have been increasingly used for construction monitoring and structural testing of bridges, are suitable devices in terms of indirect deflection measurements because of their characteristics such as high sensitivity, easy installation, and small electrical drift. The testing and evaluation procedure developed was applied on a real bridge, and the results indicated that this method could be applied to obtain vertical displacements of bridges as an alternative to the use of conventional displacement transducers.
Bridge 1-351 over Muddy Run: Design, Testing, and Erection of an All-Composite Bridge
Authors: Gillespie J. W. , Eckel D. A. , Edberg W. M. , Sabol S. A. , Mertz D. R. , Chajes M. J. , Shenton H. W. , Hu C. , Chaudhri M. , Faqiri A. , Soneji J.
Published: April 2007

Bridge 1.351 on Business Route 896 in Glasgow, Delaware, was replaced with one of the first state-owned all-composite bridges in the nation. Composites are lightweight construction materials that do not corrode, which results in benefits such as ease of construction and reduced maintenance costs. A summary of the design, large-scale testing, fabrication, erection, and monitoring of this bridge is presented. The bridge was designed to AASHTO load and resistance factor design specifications. A methodology was developed to incorporate the engineering properties of these unique composite materials into the design. The bridge consists of two 13 × 32 ft (3.96 × 9.75 m) sections joined by a unique longitudinal joint. The sections have sandwich construction consisting of a core [28 in. (71.12 cm) deep] and facesheets [0.4 to 0.6 in. (10.16 to 15.24 mm) thick] that provide shear and flexural rigidity, respectively. The composite bridge was fabricated with E-glass preforms and vinyl-ester resin, which offers excellent structural performance and long-term durability. Each of the sections was fabricated to near-net shape in a single step by a vacuum-assisted resin transfer molding process. The overall structural behavior has been accurately predicted with simple design equations based on sandwich theory for anisotropic materials. Large-scale testing of full-sized subcomponents was conducted to prove that the design satisfied deflection, fatigue, and strength limit states. A redundant longitudinal joint was designed that consisted of both an adhesively bonded vertical joint between sections and splice plates. Assembly procedures were developed, and transverse testing of the full-sized joint was conducted. Final bridge sections were proof-tested to the strength limit state. The construction phase included section positioning, joint assembly, and application of a latex-modified concrete wear surface. The bridge was reopened to traffic on November 20, 1998. Results from the long-term monitoring effort will be documented.
Fiber-Reinforced Polymer Wrapping of Deteriorated Concrete Columns
Authors: Halstead J. Preston , O’Connor Jerome S. , Luu Khuong , Alampalli Sreenivas , Minser Amy
Published: April 2007

The New York State Department of Transportation initiated a fiber-reinforced polymer (FRP) Column Wrap Demonstration Project in March 1998. The purpose of this project is to investigate the effectiveness and efficiency of preserving deteriorated concrete with FRP, its possible detrimental effects, and its viability as an alternative for concrete column repair and rehabilitation without regard to seismic considerations. To the authors’ knowledge, this is the first FRP column wrap demonstration project of its kind to involve most of the FRP wrap suppliers in the United States. A 5-year condition-monitoring program was established to monitor the performance of FRP wrapping in preserving the concrete columns. A baseline condition of the piers was established through testing, including concrete cores for compressive strength, chlorides, pH, and freeze-thaw resistance; hammer soundings; and a tight-grid survey of electric potentials. Concrete spalls were repaired; however, delaminations were not. To monitor corrosion of the column reinforcing steel, corrosion probes using linear polarization technology were embedded in the concrete. Initial corrosion readings were collected before wrapping, enhancing the observed baseline condition data. In addition, concrete humidity and temperature probes were installed through the FRP wraps, and strain gauges were mounted on the FRP wraps. Data will be collected at 3-month intervals for 4 or 5 years. The wraps will be removed after monitoring, and a complete column testing program will be implemented at that time.
Live-Load Girder Distribution Factors for Bridges Subjected to Wide Trucks
Authors: Tabsh Sami W. , Tabatabai Muna
Published: April 2007

An important problem facing engineers and officials in the United States is the constraint imposed on transportation due to limitations of bridges. These limitations typically constrain vehicles to minimum heights and widths, to minimum and maximum lengths, and to a maximum allowable weight. However, with current demands of society and industry, there are times when a truck must carry a load that exceeds the size and weight of the legal limit. In this situation, the trucking company requests from the state departments of transportation an overload permit. For a truck with a wheel gauge larger than 1.8 m (6 ft), the process of issuing a permit for an overload truck requires a tremendous amount of engineering efforts. This is because the wheel load girder distribution factors (GDFs) in the design specifications cannot be used to estimate the live-load effect in the girders. In some cases, an expensive and time-consuming finite element analysis may be needed to check the safety of the structure. In this study, the finite element method is used to develop a modification factor for the GDF in AASHTO’s LRFD Bridge Design Specifications to account for oversized trucks with a wheel gauge larger than 1.8 m. To develop this factor, nine bridges were considered with various numbers of girders, span lengths, girder spacings, and deck slab thicknesses. The results indicated that use of the proposed modification factor with the GDF in the design specifications can help increase the allowable load on slab-on-girder bridges.
Permit Vehicle Routing Using Reliability-Based Evaluation Procedures
Authors: Casas Joan R.
Published: April 2007

The works carried out within the framework of the development of an automatic system for permit vehicle routing on the Spanish National Highway network are described. The focus is on the methodology adopted for analysis of the old existing bridges. Because information about bridge properties (geometry, material strength) and design live load is unknown, the evaluation procedure combines the information provided by in situ measurements and inspection with a reliability-based evaluation. The reliability index for the most critical limit states derived from the maximum effects due to actual traffic on the bridge is adopted as the comparison value to define a passage criterion. Any permit crossing the bridge alone or with traffic restrictions leading to a lower reliability index will not be allowed on the bridge. The actual traffic load is obtained from existing traffic records using a model of traffic flow. The method is applied to 10 bridges fully representative of the old and nondocumented bridges most often encountered on Spanish highways. The final result is definition of the standard permits as presented in Eurocode 1 that are allowed on the bridge. From the most unfavorable permit, a criterion is derived concerning the actual vehicle permits.
Structural Design of High-Performance Concrete Bridge Beams
Authors: Huo Xiaoming (Sharon) , Tadros Maher K.
Published: April 2007

Recently high-performance concrete (HPC) has been used in highway bridges and has gained popularity for its short-term and prospective long-term performances. Benefits of using HPC include fewer girder lines required, longer span capacity of girders, reduced creep and shrinkage deformation, less prestress losses, longer life cycle, and less maintenance of bridges. Research has been conducted on several issues of structural design of HPC bridge beams. The topics discussed include the effects of section properties of prestressed concrete girders, allowable tensile and compressive stresses, creep and shrinkage deformations of HPC, and prediction of prestress losses with HPC. The results from a parametric study have shown that a section that can have a large number of strands placed in its bottom flange is more suitable for HPC applications. The use of 15-mm-diameter prestressing strands allows the higher prestressing force applied on sections and can provide more efficiency in HPC bridges. The research results also indicate that the allowable compressive strength of HPC has a major effect on the structural design of bridges, whereas the allowable tensile stress has a minor effect on the design. Equations for predicting prestress losses based on the experimental and analytical results are recommended. The recommended equations consider the effects of lower creep and shrinkage deformations of HPC.
Bridge Management for the 21st Century
Authors: Roberts James E. , Shepard Richard
Published: April 2007

Bridge management has been a subject of intense interest and development for the past 10 years. In support of improved bridge management, FHWA funded the development of the Pontis bridge computer program, which is now in use by approximately 40 of the 50 states. In addition, many new guide specifications have been produced to assist bridge managers in their efforts to better manage the nation’s aging bridge inventory. The AASHTO Subcommittee on Bridges and Structures has taken the lead along with FHWA in implementing the improved bridge management systems. California and a few other states have been critical of the current ranking system for bridge maintenance and have been working to develop an improved performance measure. The bridge health index (HI), an improved and more comprehensive numerical rating system that uses the element inspection data to determine the remaining asset value of a bridge or network of bridges, is discussed. The HI is more consistent with the element-level evaluation data collected and reported in the Pontis program. Examples of the application of the HI are included.
Comprehensive Bridge Scour Evaluation Methodology
Authors: Lagasse P. F. , Richardson E. V. , Zevenbergen L. W.
Published: April 2007

In the United States, bridge scour technology is discussed primarily in three FHWA publications: Hydraulic Engineering Circular (HEC) 18: Evaluating Scour at Bridges; HEC-2: Stream Stability at Highway Structures; and HEC-23: Bridge Scour and Stream Instability Countermeasures. Together, these documents provide guidance to state highway agencies that is necessary for completing comprehensive scour and stream instability evaluations for the design of new bridges and for repairing existing bridges. Experience has shown that the relationships among the three documents are not always readily apparent, and some scour evaluations have relied primarily on HEC-18. A comprehensive flowchart that illustrates the interrelationship among the three FHWA scour-related documents has been developed. In addition, in 1998, FHWA, TRB, and AASHTO sponsored a scanning review of European practice for bridge scour and stream instability countermeasures. In 1999, ASCE published a compendium of papers on stream stability and scour at highway bridges, and FHWA prepared an annotated bibliography to support revisions to the three HECs. It is anticipated that the flow-chart and the substantial information from the scanning review, the compendium, and the annotated bibliography will be included in the next revisions to HEC-18, HEC-20, and HEC-23. On the basis of information from these sources, a comprehensive approach to bridge scour and stream instability evaluations is outlined, and an overview of planned revisions to the three FHWA HECs is provided.
Seismic Hazard Study for New York City Area Bridges
Authors: Malik Ayaz H.
Published: April 2007

In the early 1990s, site-specific studies were conducted to evaluate the seismic hazard for four New York City area transportation construction projects. The rock motions developed as a result of the four independent site-specific studies reflected wide disparities in the ground motions for the city area. An expert panel was assigned the task of developing rock motions for the New York City area that can be applied uniformly for the design of new structures and retrofitting of existing structures. Summarized are the findings and the resulting changes to the New York State Department of Transportation requirement for evaluating ground motions in the city area, namely, importance classification, performance criteria, two-level seismic hazards, and site amplification factors.
European Practice for Bridge Scour and Stream Instability Countermeasures
Authors: Bryson David W. , Ghere Daniel G. , Hulbert William H.
Published: April 2007

FHWA, AASHTO, and TRB sponsored a scanning review of European practice for bridge scour and stream instability countermeasures in October 1998. The review involved a panel of representatives from six state highway agencies (California, Illinois, Maryland, Minnesota, Oregon, and South Carolina), FHWA, two universities, and the private sector. The review included visits to hydraulic research laboratories, highway research institutes, and field sites in four countries—Switzerland, Germany, the Netherlands, and the United Kingdom. Findings during the scanning review can be classified as general observations and observations of specific countermeasures. General observations of European practice include design philosophy, risk analysis, environmental policy, river geomorphology, scour prediction, modeling, and inspection and monitoring. Observations of specific countermeasures include riprap design and construction, filter design and construction, river-training structures, riverbed degradation countermeasures, bioengineering, and flow-altering devices. These observations are contrasted with U.S. practice. The panel’s recommendations for modifying U.S. practice on the basis of the European experience and findings that deserve further evaluation are also presented.
Testing the Effectiveness of Scour Countermeasures by Physical Modeling
Authors: Eisenhauer Norbert O. , Rossbach Bernd
Published: April 2007

The physical modeling of the scouring process at bridge piers is a proven method to obtain information about the size of the scour and the flow velocities that generate the scour. On the basis of this information, appropriate countermeasures can be designed. The advantage of the physical model is its application to all, even the most complex, pier geometries. Because approach flow is uniform in most cases, physical model tests can be carried out in a hydraulic flume, a method that gives fast and reliable results. The Federal Waterways and Engineering Institute (Bundesanstalt für Wasserbau) in Karlsruhe, Germany, conducted such model tests using piers of a new bridge over the Rhine River between the cities of Mannheim and Ludwigshafen. Shortly after sheet piles were driven into the riverbed as a formwork for the lower part of the pier, severe scouring of the riverbed occurred. Consequently, the stability of the sheet pile formwork was endangered. The ad hoc countermeasure of placing riprap into the scour did not stop local scouring. An additional cover layer of coarser stones was placed on top of the previous layer, stopping the erosion process at mean flow. Model tests were conducted to estimate the durability and stability of the ad hoc countermeasure for flood events. The tests proved that the riprap was stable, even at flood events, and that the scour had shifted away from the pier to the joint between the riprap and the original riverbed. A flood event with a peak of 3 days above the tested flood water level occurred in March 1999. No negative effects on the riprap have been observed until now.
User Cost Model for Bridge Management Systems
Authors: Thompson Paul D. , Soares Roberto , Choung Hong Jae , Najafi Fazil T. , Kerr Richard
Published: April 2007

User cost models are used in bridge management systems to quantify, in economic terms, the potential safety and mobility benefits of functional improvements to bridges. One component of many such models is a formula to predict traffic accident risk on the basis of bridge characteristics such as roadway width and approach roadway alignment. A critical analysis of the user cost model used in AASHTO’s Pontis and Bridgit systems found that the model was overly sensitive to extremes of roadway width, yielding unrealistically high benefit estimates. A new model was developed using Florida data on bridge characteristics and traffic accidents. The new model has superior behavior and statistical characteristics on a full inventory of state highway bridges. Since it relies solely on National Bridge Inventory data items, the model is readily transferable to many different bridge management systems.
Bond Characteristics of Overlays Placed over Bridge Decks Sealed with High-Molecular-Weight Methacrylate
Authors: Shahrooz Bahram M. , Gillum Arnol J. , Cole Jeremiah , Turer Ahmet
Published: April 2007

The bond strength between portland cement overlays and bridge decks treated with high-molecular-weight methacrylate sealers is examined. The data universally suggest that sealers reduce the available bond strength. However, extra surface preparation techniques, such as light sandblasting of the sealed surface or broadcasting sand over the surface immediately after sealing [at approximately 1 kg/m2 (20 lb/100 ft2)], restore the strengths to 80 or 85 percent, respectively, of the unsealed surface. Service-level fatigue testing and loading well beyond the serviceability limit state do not adversely affect the bond strength so long as the sealed surface is treated before the application of the overlay. Therefore, to seal the existing cracks, bridge decks may be sealed if either of the recommended secondary surface preparation techniques is followed.
Mitigation of Alkali-Silica Reactivity in New Mexico
Authors: McKeen R. Gordon , Lenke Lary R. , Pallachulla Kiran K. , Barringer William L.
Published: April 2007

The research experiments reported were conducted at the Materials Research Center, ATR Institute, University of New Mexico, at the request of the Research Bureau, New Mexico State Highway and Transportation Department (NMSHTD). The purpose was to determine the amount of additives required for mitigation of alkali-silica reactivity (ASR) based on screening tests. Fly ash additives routinely used in New Mexico and a new material—lithium nitrate—proposed by the Strategic Highway Research Program were evaluated. The work was motivated by continuous problems with early deterioration of concrete structures due to alkali-silica reactivity. The work was based on the use of acceptance criteria established by NMSHTD for expansion due to ASR, as measured in screening tests. Recommendations resulting from this research do not consider all aspects of the behavior of concrete mixtures and structures. The additive recommendations are based on reduction in mortar-bar expansion during accelerated tests.
92-MPa Air-Entrained High-Performance Concrete Using Tennessee Materials
Authors: Crouch L. K. , Sauter Heather J. , Williams Jacob A.
Published: April 2007

An air-entrained high-performance concrete (HPC) mixture design for prestressed bridge beams was developed in an attempt to interest the Tennessee Department of Transportation. The mixture contained locally available, 19-mm maximum-size limestone as the coarse aggregate and a manufactured limestone fine aggregate. A dense, combined aggregate gradation was used to lower water demand and thus enhance durability. Type II portland cement, microsilica, and Class C fly ash were used as binder materials. The resulting w/(c + p) was 0.22. Twelve 0.028-m3 batches of the HPC were mixed for the study. The mixture design produced an average air content of 4.1 percent and an average slump of 72 mm. Although it contained 4.1 percent air, the mixture remained very dense, with an average unit weight of 2422 kg/m3. Average compressive strengths of 72.6, 63.3, 84.8, and 92.9 MPa were achieved at simulated release at 7, 28, and 56 days, respectively. Measured static modulus of elasticity at 28 days agreed with ACI 363R-92 equations within 2 percent. Further, after 600 freezing and thawing cycles, the average durability factor of two prismatic specimens was 100, and visible damage was minimal.
Variations in the Short- and Long-Term Characteristics of Bridge Concrete Due to Transportation Techniques
Authors: Yazdani Nur , Bergin Michael , Mujtaba Ghulam
Published: April 2007

The short-term effects of pumping on concrete are well documented, although the long-term effects on concrete durability are not known. Pumping of concrete is widely used in large highway projects because of its convenience and economy of placement. Both types of effects were studied through collection and testing of 73 concrete samples from the Florida Department of Transportation (FDOT) bridge construction sites before and after pumping. The tests performed were air content, slump, unit weight, compressive strength, rapid chloride permeability, and water permeability. The air content and the slump of concrete decreased by about 1 percent and 13 mm (0.5 in.) on average, respectively, due to pumping. The unit weight and compressive strength of concrete increased by about 24 kg/m3 (1.5 pcf) and 1.83 MPa (266 psi), respectively, due to pumping. Pumping decreased the water and chloride ion permeabilities in the majority of tested samples. Results show that pumping does not have detrimental effects on concrete properties; in fact, in many cases, it results in stronger, denser, and more durable concrete. Results indicate that pumping can be continued with confidence as a means of concrete placement in FDOT projects.
Early Strength of Self-Compacting Concrete
Authors: Mukai David J. , Altan Simten , Ehrgott John Q.
Published: April 2007

The researchers’ primary objective was to evaluate the early-strength characteristics of self-compacting concrete (SCC), which is a type of concrete that can be placed without external vibration, even in congested areas. Two unique characteristics of SCC are its high-percentage substitution of cement with fly ash or slag cement, or with both fly ash and slag cement and a relatively high superplasticizer dosage. Both of these characteristics retard early-strength gain. The impetus was to develop self-compacting concrete with an early strength suitable for precast applications. The major findings are that it is possible to proportion SCC mixtures with high early strength (30 MPa at 16 h under steam curing) and that high slump does not necessarily correlate with self-compaction.
Incorporating Road Safety into Pavement Management
Authors: Tighe Susan , Li Ningyuan , Falls Lynne Cowe , Haas Ralph
Published: April 2007

Improving road safety through proper pavement engineering and maintenance should be one of the major objectives of pavement management systems. When pavements are evaluated in terms of safety, a number of factors related to pavement engineering properties are raised, such as pavement geometric design, paving materials and mix design, pavement surface properties, shoulder type, and pavement color and visibility. Each year there are voluminous annual reports on traffic accident statistics and discussions of such road safety issues as road safety modeling and pavement safety measurements and criteria. Although road safety may be considered a separate area, it should be incorporated into pavement management systems. The main pavement engineering relationships associated with road safety are identified, and the various aspects of road safety related to pavement management, such as pavement types, pavement surface macrotexture and microtexture, and pavement safety measurements, criteria, and evaluation methods, are discussed. A systematic approach is proposed for the coordination of pavement maintenance programs with road safety improvement and the incorporation or integration of safety management with pavement and other management systems. Finally, a list of possible remedial measures for road safety improvements associated with pavement maintenance activities is recommended.
Development of Pavement Type Evaluation Procedure for Texas Department of Transportation
Authors: Beg Muhammad Arif , Zhang Zhanmin , Hudson W. Ronald
Published: April 2007

A rational procedure is presented for evaluating alternative pavement types for roadway projects. Agency costs, user delay costs, and performance levels are important factors for comparing alternative pavement strategies. These factors are included in the evaluation procedure. Economic evaluations are based on life-cycle cost analysis. Cost-effectiveness analysis is also included in the procedure and uses area under the performance curve as a measure of the effectiveness of a pavement design strategy. Limitations in economic evaluations and the role of other miscellaneous factors in pavement type selection are also discussed. A computer program, TxPTS, was developed to automate the evaluation procedure. Case studies are presented demonstrating the use of the program.
Road User Cost Models for Network-Level Pavement Management
Authors: Vadakpat Govindarajan , Stoffels Shelley , Dixon Karen
Published: April 2007

Life-cycle cost analysis (LCCA) of pavements is a process for evaluating total economic worth of a usable project segment by analyzing initial costs and discounted future costs, such as those for maintenance, reconstruction, rehabilitation, and resurfacing. One of the most important ingredients in the LCCA process, at either a network level or a project level, is the determination of road user cost (RUC) during maintenance and rehabilitation operations. RUC models are also important in contracting strategies, which take into account time for a project to be completed for award and payment. Methods used to date to determine RUC are exclusively analytical in nature. Microscopic estimates of traffic are used to determine RUC. CORSIM, a microscopic traffic simulation program developed by FHWA, was used for this research. Models for additional travel time, added fuel consumption, and RUC for standard two-to-one lane closure scenarios are presented.
Applying Economic Concepts from Life-Cycle Cost Analysis to Pavement Management Analysis
Authors: Zimmerman Kathryn A. , Smith Kurt D. , Grogg Max G.
Published: April 2007

In recent years, FHWA has made a concerted effort to develop guidelines for the use of life-cycle cost analysis by transportation agencies and to promote the use of multiyear prioritization in pavement management. These efforts resulted in the development of a Technical Bulletin and Demonstration Project course materials that have been presented to state highway agencies throughout the country. A key part of multiyear prioritization is emphasis on the use of life-cycle cost information in cost-effectiveness calculations. An agency implementing multiyear prioritization as part of its pavement management system would naturally attempt to utilize the FHWA’s guidelines in developing the cost component of its economic analysis. However, because of the types of analyses required in pavement management and the ways in which cost information is reported and used, the recommendations provided in FHWA’s Technical Bulletin cannot be applied directly. The types of economic analyses that are used in an incremental benefit-cost analysis and the types of economic considerations that must be taken into account are discussed. Several of these economic considerations differ from the recommendations made in FHWA’s Technical Bulletin, so the reasons for these variations are also described.
Public Perceptions of Wisconsin Pavements and Trade-Offs in Pavement Improvement
Authors: Robinson Richard K. , Kuemmel David A. , Sonntag Ronald C. , Shober Stephen F. , Griffin Robert J.
Published: April 2007

Findings are reported from Phase II of a three-phase pooled-fund project in Wisconsin, Iowa, and Minnesota to determine perceptions of drivers regarding pavement of rural two-lane highways. Among the survey topics were drivers’ trust in the state department of transportation (DOT), pavement improvement trade-offs, and pavement evaluation. Results of the Wisconsin portion of the survey data are the focus of this study. The survey questionnaire was based in part on Phase I focus groups conducted to gauge beliefs about pavements as well as the language describing ruts, tining, and other pavement characteristics. Phase II entailed a statewide telephone survey of at least 400 randomly selected drivers in each of the three states. Although the focus here is on Wisconsin results, survey responses across the three states were very consistent. Included in the findings discussed are perceptions of pavement and the state DOT and pavement improvement options relating to construction, travel time, and delays. Results disclose key public perceptions of priorities with regard to spending limited funds. Also discussed are statistically significant relationships providing additional insights into public perceptions and pavement improvement on rural two-lane highways.
Proposed Pavement Performance Models for Local Government Agencies in Michigan
Authors: de Melo e Silva Fernando , Van Dam Thomas J. , Bulleit William M. , Ylitalo Ross
Published: April 2007

The state of Michigan has 191 432 km (118,950 mi) of roadway (paved and unpaved), including highways, roads, and streets. Local government agencies, which are responsible for 176 270 km (109,529 mi) of these roads and streets, commonly use a pavement management system (PMS) called RoadSoft to assist in managing their pavement network. A key element of any PMS is its ability to predict future pavement performance. A study is described in which various deterministic and probabilistic models were evaluated using data from two Michigan counties. It was found that the logistic growth model and the Markov model provided the best combination of predictive ability and potential for applicability in Michigan counties. A comparison between these models found that their predictive ability for four pavement segments with different deterioration rates was good, with the Markov model offering the added advantage of representing future performance as a probability distribution, not as a single condition state. Current plans are to implement the logistic growth model in RoadSoft by the end of 1999 and to add the Markov model as local organizations gather sufficient pavement condition data over the next 5 years. It is hoped that these two pavement deterioration models can be implemented in the RoadSoft PMS to improve pavement performance prediction.
Solution of Pavement Deterioration Equations by Genetic Algorithms
Authors: Raja Shekharan A.
Published: April 2007

Pavement deterioration models are indispensable for many purposes; as a result, a number of models are in use. Models with simple equation forms are easier to use, but frequently such models may not suffice for many purposes. Consequently, complex nonlinear forms of models are to be considered. However, determination of the solution to a complex model form is not an easy task. There are various methods of obtaining solutions to such models, with each method having its own advantages and disadvantages. The use of genetic algorithms for model development is examined in this study. A very brief description of genetic algorithms is included, and their application for the development of a model is illustrated. Five models of varied complexities, extracted from the literature, are employed to create databases in which the relationship between the response and the predictor variables is known. The solutions to the models are developed employing genetic algorithms. The results indicate a high degree of accuracy, which suggests that genetic algorithms are useful as a tool for development of solutions to pavement deterioration models.
Simulation Model for Calculating Pavement Temperatures Including Maximum Temperature
Authors: Hermansson Åke
Published: April 2007

A simulation model has been developed to calculate the temperatures of asphalt concrete during summer. Input data to the simulation model are hourly values for solar radiation, air temperature, and wind velocity. Longwave radiation incident to and outgoing from the pavement surface is calculated from the air and pavement surface temperatures, respectively. The portion of the incident shortwave radiation absorbed by the pavement surface is calculated from the albedo of the surface. By means of a finite difference approximation of the heat transfer equation, the temperatures are calculated under the surface. Apart from radiation and heat transfer, convection losses from the pavement surface are also calculated depending on wind velocity, air temperature, and surface temperature. The formulas used for the calculation of radiation and the simulation model as a whole are validated by comparison with measurements, showing good agreement. A method for the calculation of direct solar radiation from a clear sky, at an arbitrary location and time, is used to create input data to the simulation model in order to calculate maximum pavement temperatures. The formulas used with Superpave to calculate maximum pavement temperatures are based on the assumption that there is an equilibrium when a maximum temperature is reached. Such an equilibrium assumption can be strongly questioned, and its consequences are discussed.
Accuracy of Weather Data in Long-Term Pavement Performance Program Database
Authors: Wu Chung-Lung , Rada Gonzalo R. , Lopez Aramis , Fang Yingwu
Published: April 2007

To provide accurate climatic data for pavements under the Long-Term Pavement Performance (LTPP) Program, a climatic database was developed in 1992 and subsequently revised and expanded in 1998. In the development of this database, up to five nearby weather stations were selected for each test site. Pertinent weather data for the selected weather stations were obtained from the U.S. National Climatic Data Center and the Canadian Climatic Center. With a 1/ R2 weighting scheme, site-specific climatic data were derived from the nearby weather station data. The derived data were referred to as “virtual”weather data. To evaluate the effect of environmental factors on pavement performance and design, automated weather stations (AWS) were installed at LTPP Specific Pavement Study Projects 1, 2, and 8 to collect on-site weather data. Since the virtual weather data were developed for all LTPP test sites and will be used for future pavement performance studies, it is essential that the derived virtual data be accurate and representative of the actual onsite climatic conditions. The availability of the AWS weather data has provided an opportunity to evaluate whether virtual weather data can be used to represent on-site weather conditions. Daily temperature data and monthly temperature and precipitation data were used in this experiment. On the basis of the comparisons made between the virtual and onsite measured (AWS) data, it appears that climatic data derived from nearby weather stations using the 1/R2 weighting scheme estimate the actual weather data reasonably well and thus can be used to represent on-site weather conditions in pavement research and design.
Winter Storm Event Volume Impact Analysis Using Multiple-Source Archived Monitoring Data
Authors: Knapp Keith K. , Smithson Leland D.
Published: April 2007

Data collection and information management systems typically are implemented to improve decision-making efficiency and capabilities. Results of these systems sometimes are used in real-time scenarios; however, in other instances, the data are collected and summarized, then archived or possibly destroyed. Data from several information management systems in Iowa were used to analyze the traffic volume impacts of winter storm events. Roadway and weather condition data were acquired from a roadway weather information system, and hourly traffic volumes were obtained from automatic traffic recorders. Daily snowfall data were acquired from the Iowa Department of Agriculture and Land Stewardship and the National Weather Service. Winter storm events with at least a 4-h duration and snowfall at 0.51 cm/h (0.20 in./h) or more were evaluated. Overall, 64 winter storm events were defined and analyzed for seven interstate locations. The analysis indicated that winter storm events generally decrease traffic volumes, although the impact can vary greatly. The calculated average winter storm event volume reduction was approximately 29 percent, but ranged (by data collection location) from approximately 16 to 47 percent. Regression analysis revealed a statistically significant positive relationship between winter storm event percent volume reduction, total snowfall, and the square of maximum gust wind speed. This research can be used to determine the potential volume impacts of winter storm events and provide additional data for the eventual development of a winter-weather level of service system based on traffic flow characteristics.
Rural Intelligent Transportation System for Snow Avalanche Detection and Warning
Authors: Rice Robert , Decker Rand , Jensen Newel , Patterson Ralph , Singer Stanford
Published: April 2007

The growth of winter travel on alpine roads in the western United States, a result of the demand for reliable winter access, has increased the hazard to motorists and highway maintenance personnel from snow avalanches. Configurations are presented for systems that can detect and provide, in real time, warnings to motorists and highway maintainers of roadway avalanches. These warnings include on-site traffic control signing, in-vehicle audio alarms for winter maintenance vehicles, and notifying maintenance facilities or centralized agency dispatchers. These avalanche detection and warning systems can detect an existing avalanche and use the avalanche’s remaining time of descent to initiate on-site alarms. Alternatively, real-time knowledge and notification of the onset of avalanching may be used to proactively manage the evolving hazard over an affected length or corridor of highway. These corridors can be several tens of kilometers in length and may be very remote, low-volume rural highways. As a consequence, these detection and warning systems must be cost-effective alternatives to existing avalanche hazard reduction technology. Results and experiences from the winters of 1997–1998 and 1998–1999 are presented, along with recommendations and criteria for future deployment of these automated natural hazard reduction systems for rural transportation corridors.
Road Safety Benefits of Liquid Anti-Icing Strategies and Agents: Kamloops, British Columbia, Canada
Authors: Gilfillan Graham
Published: April 2007

The Insurance Corporation of British Columbia (ICBC) formed a partnership with the city of Kamloops in September 1996 to undertake a 2-year project to test the effectiveness of liquid anti-icers in preventing motor vehicle accidents compared with traditional deicing techniques. ICBC provided $131,000 in financing to Kamloops over the 2 years. Costs included the conversion of city trucks for liquid dispensing, purchasing of liquid magnesium chloride (Freezgard GSL), and updated road weather information systems. G. D. Hamilton and Associates, an engineering and consulting firm in Vancouver, British Columbia, evaluated the safety benefits achieved during the 2 years. The results of the analysis show up to a 74 percent reduction in overall slush, snow, and ice collisions and associated insurance claims. In the previous 3 years, traditional deicing methods were used. The study area for 1996–1997 consisted of 46 km of arterial streets and 38 km of highways within the city of Kamloops. In the second year, 1997–1998, 148 km of arterial and collector roads were studied. However, the anti-icing agent was not applied to the highways in the second year, and the analysis further showed an increase of 84 percent in the overall slush, snow, and ice collisions and resulting claims. The ICBC Research Department evaluated accident claims reported to the Kamloops Claims Office for winter 1997–1998. The results of the analysis show a 6 percent reduction in overall claims on relevant snow days for an estimated minimum savings of $281,868.00 to ICBC for that year. A similar study was completed in 1998–1999 and showed an 8 percent reduction in overall claims on relevant snow days. For the 3-year program, 285 fewer claims were filed, an average of 95 fewer claims per year.
Environmental Implications of the Use of “Ice Ban” as a Prewetting Agent for Sodium Chloride
Authors: Michael Fitch G. , Roosevelt Daniel S.
Published: April 2007

Ice Ban is the registered trade name of a group of agricultural byproducts patented for use as roadway deicing/anti-icing agents. Ice Ban is applied primarily in anti-icing operations as a direct liquid or prewetting agent. Because Ice Ban is far more expensive to use than the traditional chemicals for snow removal and ice control, it may be cost-effective only if it can reduce equipment corrosion, infrastructure damage, and the adverse environmental effects of traditional chemicals while maintaining at least the same level of service. A study was conducted to evaluate particular environmental effects of Ice Ban M50 when used as a prewetting agent for salt. The agent’s effects on turf grass seed, freshwater minnows, and roadside vegetation were determined and compared with the effects of salt alone, salt prewetted with magnesium chloride, or both. When used as a prewetting liquid at the spinner, Ice Ban M50 had little impact on the effect of salt on turf grass seed germination, freshwater minnow mortality, or roadside vegetation stress.
Safety Effects of Limited Stopping Sight Distance on Crest Vertical Curves
Authors: Fitzpatrick Kay , Fambro Daniel B. , Stoddard Angela M.
Published: April 2007

Previous studies that examined the relationship between stopping sight distance and safety have been inconclusive and inconsistent; however, the fact that a relationship has not been established does not necessarily imply that stopping sight distance is not a contributing factor in some crashes. Instead, it means that existing databases have failed to quantify any relationship that might exist. A promising approach to identifying such a relationship is a detailed examination or case study of crashes from a relatively large sample of limited sight distance roadways. If limited sight distance is a factor that contributes to crashes, it should show up in such a study. The objective of this study was to determine whether stopping sight distance was a contributing factor in crashes on roadway segments with limited sight distance crest vertical curves. This objective was accomplished by reviewing 439 narratives from crashes that occurred on 33 multilane and two-lane roadways with limited sight distance crest vertical curves. The findings suggest that the crash rates on rural two-lane highways with limited stopping sight distance are similar to the crash rates on all two-lane rural highways. They also suggest that the percentage of accidents involving large trucks and older drivers is similar on limited sight distance highways and all two-lane rural highways. Thus, for the range of conditions studied, limited stopping sight distance does not appear to be a safety problem.