bluuebunny/crossref_metadata_2025 huggingface dataset:
Multiproduct Network Analysis of Freight Land Transport Between Mexico and the United States
Authors: Mendoza Alberto , Gil Claudia Z. , Trejo Juan M.
Published: April 2007

Truck and rail freight transportation are considered as a first stage in an effort to analyze, by means of network assignment models, freight transportation operations between Mexico and the United States. A set of background information is first presented (i.e., the evolution of trade between Mexico and the United States, participation of rail and truck in this commercial exchange, and modal share between these two modes in such a trade). The assignment model that was developed to predict the freight flows in the truck and rail intermodal network for different product categories (multiproduct) is then described. Finally, values that characterize the operation of the land modes for freight transportation between Mexico and the United States are quantified. Results and analyses that were derived from the model include quantification of ton-kilometers and transportation costs for each product type, as well as assessment of the minimum-cost freight modal share between truck and rail. Some of the analyses presented are by product category (disaggregated), whereas others correspond to the aggregated demand. Most of the analyses reported herein correspond to 1996. The growth trends of the freight volumes between the two countries, together with the optimal share results obtained, are indicative of a conspicuous growth potential for the demand of rail transportation in this type of commercial exchange.
Practical Realization of a New Concept for Asphalt Compaction
Authors: Rickards Ian , Goodman Stephen , Pagani Joanne , El Halim A. O. Abd , Haas Ralph
Published: April 2007

Australian field trials of the asphalt multi-integrated roller (AMIR) compactor confirmed the findings of Canadian trials. Consequently a successor to AMIR, hot-iron process asphalt compaction, was designed, fabricated, and tested in 1998 in Australia. With this technology, asphalt mixes can be compacted to equal or greater density with fewer passes than with conventional rolling. Furthermore, there is less variation in density, roller-induced cracking is eliminated, in situ permeability is much lower, and tensile strength and fatigue life are significantly higher. What occurs during the compaction of asphalt concrete mixes is described. The key to this concept is how the binder acts as a lubricant and how the granular particles are reoriented during compaction. Because of significant behavioral differences between unbound granular materials and asphalt concrete, it is suggested that asphalt compaction methods that emulate compaction of unbound granular materials are fundamentally flawed. It is proposed that the behavior of asphalt concrete during compaction may be more accurately modeled with consolidation theory, much like a fine-grained soil. Asphalt compaction is then a fluid flow problem, not the simple particle reorientation required for unbound material compaction. Therefore, the best way to achieve optimum compaction is to supply pressure over a sufficient interval of time. How fluid flow, air flow, and associated particle orientation work together to develop the desired asphalt service characteristics through pressure, contact area, temperature, and load duration are described. Results of analytical and field investigations are presented to support the proposed consolidation-fluid flow model of asphalt compaction.
Innovative Hot In-Place Recycling of Hot-Mix Asphalt Pavement in Mississippi
Authors: Crawley Alfred B.
Published: April 2007

A hot in-place recycling (HIR) project using the MARTEC process was constructed on Interstate 55 in Mississippi from December 1997 to July 1998, the first use of this equipment in the United States. Project size was 180 600 m2 (216,000 yd2). This equipment differed from earlier HIR equipment principally in the method of heating the hot-mix asphalt (HMA). Air heated to 600°C (1,100°F) was produced in a diesel-fired furnace and blown onto the pavement through a manifold. An elevated pugmill performed the final mixing after which the recycled mixture dropped into the hopper of an HMA paver. Principal objectives of this project were to evaluate this equipment to satisfactorily recycle to a depth of 50 mm (2 in.) and to evaluate the use of Superpave technology for design of the HIR mixture and quality control during construction. Preliminary testing with a dynamic shear rheometer (DSR) was used to select a rejuvenator and an initial point for mixture design. Quality control testing with a Superpave gyratory compactor at the field laboratory was used to make adjustments in the recycled mixture. Limited DSR data from recovered binder indicate acceptable properties. An asphalt pavement analyzer was used to compare the HIR mixture with HMA by using differing binder grades. Although construction problems were encountered, it has been shown that this equipment can adequately heat an existing HMA pavement to permit hot in-place recycling to a depth of 50 mm. Both acceptable density and ride quality are attainable.
Structural Field Testing of Flexible Pavement Layers with Seismic Methods for Quality Control
Authors: Nazarian S. , Yuan D. , Tandon V.
Published: April 2007

Current mechanistic procedures for structural design of flexible pavements consider the modulus and Poisson’s ratio of each layer. Unfortunately, the construction specifications are not based on these engineering properties. The acceptance criteria typically are based on adequate density of the placed and compacted materials. To successfully implement any mechanistic pavement design procedure, and to move toward performance-based specifications, it is essential to develop tools that can measure the modulus and Poisson’s ratio of each layer. Presented is an approach to such a program based on seismic testing. Field protocols and test equipment, which in a rational manner combine the results from laboratory and field tests with those used for quality control during construction, are discussed. A series of simplified laboratory tests that are compatible with the field tests also can be used; these methods are discussed. Several case studies are included to present some results that can be obtained with the methodology. Several issues that remain to be addressed are included.
Development of a Method for Early Prediction of the Asphalt Content of Hot-Mix Asphalt by Ignition Test
Authors: Mallick Rajib B. , Brown Elton Ray
Published: April 2007

The ignition test, developed by the National Center for Asphalt Technology, has proved to be a fast, pollution-free, automated, and inexpensive method for determining the asphalt content of a hot-mix asphalt (HMA) sample. The time required to perform this test is about 30 to 40 min, which is significantly less than the time required to perform a solvent extraction test procedure. However, having the ability to determine asphalt content in 10 to 15 min would allow the technician to identify any problem in mix production much earlier and thus save a significant amount of time and money. Presented are the results of a study carried out to develop a method for estimating the asphalt content of an HMA sample within 10 to 15 min after testing begins. The method consists of determining the prediction factor on the basis of test results from two samples and then predicting the asphalt content of additional samples on the basis of the prediction factor and the asphalt content loss at 10 to 15 min of test. Use of this method is expected to provide a good estimate of the measured asphalt content in less than half the test time. This shortcut method should be used for quality control only and should not be used for acceptance or rejection of the mixtures.
Nuclear Density Readings and Core Densities: A Comparative Study
Authors: Choubane Bouzid , Upshaw Patrick B. , Sholar Gregory A. , Page Gale C. , Musselman James A.
Published: April 2007

Presented are the findings of an investigation performed to identify possible correlations between nuclear density gauge readings and core density results. The nuclear density data were collected on a Superpave section of I-95 in Brevard County, Florida. Core samples also were obtained from this section for laboratory density determination. Five gauge units [Troxler models 3401, 3440 (two units), 3450, and 4640] and three core density methods (Florida test method FM 1-T 166, ASTM D1188, and dimensional analysis) were considered. The relationships among the core density results were analyzed, then an investigation of the correlation among the different gauges used in this study was evaluated. Finally, the performance of each of the units with respect to the core density results was assessed. The findings indicated that the five nuclear gauge density units did not always produce similar results and did not consistently correlate with the core densities. In addition, the nuclear density testing variability differed not only from gauge to gauge but also from location to location within each gauge.
Conditions of Suspension Bridge Cables: New York City Case Study
Authors: Betti Raimondo , Yanev Bojidar
Published: April 2007

From the opening of the Brooklyn Bridge in 1883 to the opening of the Verrazano Narrows Bridge in 1964 the New York City Metropolitan Area was the center of the most intensive construction of record-breaking suspension bridges worldwide. Of the 10 suspension bridges in the area, 5 established span-length records at their completion. As the twentieth century draws to a close the current records are held elsewhere and these bridges hold a record for the average age and total traffic they have jointly accumulated over the last 115 years. An understanding of suspension bridge behavior can be gained nowhere better than in the examination of the New York examples. In an unprecedented joint effort partly including the New York City Department of Transportation, the New York State Bridge Authority, and the Port Authority of New York and New Jersey, all available information and present common recommendations and guidelines for inspection and rehabilitation of the cable systems were pooled. Some conclusions about the resulting comprehensive study on the condition of cable systems in suspension bridges located in the New York Metropolitan Area are presented.
Tendon Corrosion in Precast Segmental Bridges
Authors: Wouters Jeffrey P. , Kesner Keith , Poston Randall W.
Published: April 2007

Tendon corrosion of grouted internal tendons in precast segmental bridges is reviewed, with an emphasis on the role of grouting in the corrosion protection of posttensioning. An analysis and compilation of the available information on the subject was conducted as part of an NCHRP research study (NCHRP Project 20-7, Task 92) with emphasis on those structures located in the United States and the United Kingdom. It was determined that the corrosion problems with precast segmental and posttensioned bridges in the United Kingdom principally were due to poor design choices and poor quality construction, not a significant intrinsic susceptibility to corrosion. The study found no evidence of corrosion or other durability problems with precast segmental bridges in the United States, although it must be recognized that this conclusion is based on reported information primarily gathered by visual inspection. Similar to the experience in the United Kingdom, the few reported problems with grouted posttensioned structures in the United States were due to poor quality construction. Additionally, laboratory research indicates that properly designed and constructed precast segmental and posttensioned structures are corrosion resistant. To ensure good future performance of precast segmental bridges, high-quality design details and proper construction practices must be continued, especially when using internal tendons. It is important to adopt more stringent grouting requirements and inspection procedures in the United States, similar to what has been done in the United Kingdom, to ensure that the tendons are completely encapsulated in a high-quality grout.
In-House Versus Consultant Design Costs in State Departments of Transportation
Authors: Wilmot Chester G. , Deis Donald R. , Schneider Helmut , Coates Charles H.
Published: April 2007

The use of consultants in providing preconstruction engineering design services for state departments of transportation has increased over the last 20 years. This has resulted in several investigations into the cost-effectiveness of this trend. This paper reviews past studies, examines their methodology, suggests improvements to certain parts of the commonly used investigative process, and demonstrates their use in an application to the Louisiana Department of Transportation and Development. The suggested improvements include using the same project to compare in-house and consultant design costs (instead of the use of similar projects, as in most studies), performing a detailed analysis of overhead rates that are comparable between state and consultants, and measuring comparative design costs as the ratio of in-house to consultant design costs instead of as the ratio of design to construction cost commonly used in past studies. Most previous studies have concluded that consultant design costs are higher than in-house costs or that there is not a significant difference in cost between the two. The Louisiana study found that consultants are approximately 20 percent more expensive than in-house staff in producing road and bridge designs but that the difference was almost entirely due to the extra cost of contract preparation and in-house supervision required for consultant designs. The study also identified factors other than cost that are used in decision making to employ consultants.
Design-Build Effects on a Construction Company: A Case Study
Authors: Ernzen James J. , Schexnayder Cliff , Flora Gwen
Published: April 2007

A comparative study of the design-build and non-design-build project delivery experiences of one construction company was conducted to measure the advantages and disadvantages of both delivery methods. Five categories—business practices, employee satisfaction, safety, labor costs, and profit margins—were selected for study. The categories gave a broad analysis of the effect each project delivery method had on the construction project team. The business practice review revealed four categories of importance in design-build practices: team member roles and relationships, risks, strategies, and owner relationships. The employee survey targeted the contractor’s field-level management and consisted of seven open-ended questions. The respondents were consistently optimistic about design-build practices within the company. The contractor’s design-build and non-design-build safety records, from 1991 through 1997, were compared. The results indicated that the design-build projects experienced more minor accidents but fewer major accidents. Labor reports from two similar highway projects, one design-build and one design-bid-build, were compared. The design-build project had lower labor costs but increased quantity and cost variability. The profit margin analysis revealed that design-build project average profit margin was 3.5 percent greater than non-design-build.
Use of Falling Weight Deflectometer and Dynamic Cone Penetrometer in Pavement Evaluation
Authors: Chen Jianzhou , Hossain Mustaque , Latorella Todd M.
Published: April 2007

The Kansas Department of Transportation (KDOT) has been using the falling weight deflectometer (FWD) and dynamic cone penetrometer (DCP) for pavement evaluation since the early 1990s. KDOT experience has shown that the existing relationships between the output of the DCP test (DCP value) and the California bearing ratio (CBR) and between CBR and subgrade modulus resulted in widely varying sub-grade moduli along the project length. These relationships appeared to be unreliable for relatively high CBR or low DCP values. In this study, the FWD deflection data and DCP results on six KDOT pavement projects were analyzed to develop a relationship between the DCP values and FWD-backcalculated subgrade moduli. Results of the linear regression analysis show that the best regression equation is a power model with the coefficient of determination, R2, ranging from 0.72 to 0.95 for individual pavement sections. The global power model has an R2 value of 0.42. The model provides a new approach toward interpreting DCP results that is consistent and reliable for applications in pavement evaluation and design. A better correlation equation for global application could be obtained by including some common soil properties, such as moisture content, plasticity index, and dry density, in the model.
Performance Evaluation of Backcalculation Algorithms Through Three-Dimensional Finite-Element Modeling of Pavement Structures
Authors: Shoukry Samir N. , William Gergis W.
Published: April 2007

Currently, the only means of assessing the performance of a backcalculation algorithm is to compare its results with the values obtained through laboratory measurements of core samples. Discrepancies are attributed to the inability of replicating in laboratory tests the same consolidation and stress conditions encountered in the field. In this paper, an explicit three-dimensional (3D) finite-element model (FEM) is used to back-calculate the layer moduli of rigid, flexible, and composite pavement structures. The modeling approach accounts for the dynamic nature of the falling weight deflectometer (FWD) load, friction at pavement-layer interfaces, and the 3D geometrical characteristics of the pavement structure. The FWD-measured and FEM-generated deflection basins are matched by adjusting the values of layer moduli used in the FEM. The backcalculated moduli using 3D FEM are compared with the results obtained from three backcalculation programs: MODCOMP, MODULUS, and EVERCALC. The results indicate that the three programs have an excellent capability of predicting the FEM-generated subgrade modulus values for flexible, composite, and rigid pavements provided that a correction factor is used. A correction factor for backcalculated subgrade modulus is estimated for each program and pavement type. The mechanistically evaluated correction factors were found to be in close agreement with the experience-based values recommended for flexible and rigid pavements in the American Association of State Highway Officials pavement design guide.
Investigation of Asphalt Concrete Layer Strains from Wide-Base Tires
Authors: Siddharthan Raj V. , Sebaaly Peter E.
Published: April 2007

The application of a continuum-based finite-layer mechanistic model to evaluate pavement strain response under moving traffic loading generated from wide-base tires is presented. The model incorporates important pavement response factors such as the noncircular contact area, complex contact stress distributions (normal and shear), vehicle speed, and viscoelastic material characterization. Results of a parametric study in which two typical thin and thick pavement sections were subjected to traffic loading moving at different speeds are included. The impact of vehicle speed on the strains induced in the asphalt concrete layer is consistent with the results from several field studies. The study reveals that especially in the case of thick pavements, the fatigue failure mechanism resulting from wide-base tires is different from those generated by conventional tires. With thick pavements longitudinal fatigue cracks are expected when wide-base tires are used.
Characterization of Transverse Profile
Authors: Simpson Amy L.
Published: April 2007

The Long-Term Pavement Performance (LTPP) program currently being conducted by the Federal Highway Administration is collecting transverse profile data on each of the asphalt-surfaced test sections included in the study. These data have been collected since monitoring was begun on these sections in 1989. A study was undertaken to provide indexes that summarized these x-y profiles. A study was conducted to recommend profiles to be included in the LTPP database in which six indexes were recommended to be included in the National Information Management System (NIMS). These six indexes and how they relate to each other are examined in this paper.
Use of Relational Database Management Systems Principles in Reliable Prediction of Pavement Skid Resistance
Authors: Prasanna R. , Nageswaran B. , Jayawickrama P. W.
Published: April 2007

Findings are presented from a research study conducted at Texas Tech University on the skid resistance of hot-mix asphalt concrete surfaces. The background on problems of evaluating aggregate sources using the results of laboratory tests and field skid resistance history is presented, and the methodology adopted by researchers is discussed briefly. The study findings indicate that by using a combination of tests, such as acid-insoluble residue (AIR) and petrography analysis, aggregates can be classified into three major groups: low AIR carbonates, high AIR carbonates, and noncarbonates. Skid performance rating (SPR) values were used to correlate the laboratory test results. It was found that laboratory test results of high AIR carbonates and noncarbonates provide good correlation with SPR values. However, the laboratory tests of low AIR carbonates show poor correlation with SPR values. The problems of implementing the results are discussed from the viewpoint of a pavement engineer. An entity-relationship (ER) modeling technique was used to analyze and design a database application specifically created as a tool to assist pavement materials engineers. The database application, SKIDRATE, combines relational database management principles and the results of statistical regression models obtained in this study. Thus, SKIDRATE serves the dual objective of effective data management and data processing. Essential features of the application and its use to evaluate field skid performance of aggregates are briefly explained.
Measurement, Analysis, Evaluation, and Restoration of Skid Resistance on Streets of Muscat
Authors: Ali Galal A. , Al-Mahrooqi Rashid , Al-Mammari Mohammed , Al-Hinai Nasser , Taha Ramzi
Published: April 2007

This research was undertaken to study the problems of skidding, particularly during the wet season. Thirty-nine typical street sections of known service age and traffic were selected from the Muscat area for field investigation. Six age groups were used, ranging from ⩽0.5 to >10 years, with five to eight road sections in each group. Traffic-level categories were low, medium, and high. Field measurements of dry and wet friction coefficients were undertaken for 6 months using a pendulum skid tester and a motometer decelerometer mounted on a test car. Site measurements included surface temperature, length of skidding, texture depth, and assessment of pavement condition. Cored samples 100 mm in diameter were visually evaluated and laboratory tested. The experimental work included determination of asphalt mix content and gradation, Los Angeles abrasion, and acid-insoluble residue of the extracted aggregates. Various relationships between friction coefficient and the relevant independent variables were developed. A predictive relationship between the friction coefficient and the skid length was obtained. Minimum required values of friction coefficient were recommended for safe performance. On the basis of criteria such as those proposed in this study, recommendations were made to immediately maintain eight streets to increase their skid resistance followed by others with different maintenance priorities to improve skid resistance. Open-graded friction courses are strongly recommended to reduce wet-weather skidding. The results of this research will have a positive effect on constructing and maintaining roads to reduce skidding accidents.
Performance Comparison of Base Materials Under Accelerated Loading
Authors: Djakfar Ludfi , Roberts Freddy L.
Published: April 2007

The Louisiana Transportation Research Center (LTRC) recently conducted a research effort using the Accelerated Loading Facility (ALF). Nine test sections were constructed for this research using the same wearing course material but having different thicknesses of crushed stone and soil cement bases and subbases. The soil cement base is the most commonly used base material in Louisiana, and crushed stone is a preferred base material in northern Louisiana. The performance of several configurations of crushed stone and soil cement constructed at the Pavement Research Facility and tested using the ALF machine is compared. The comparisons are based on rutting, roughness, and crack development measured on each lane during ALF loading. From the analysis it was found that the combination of crushed stone base over a soil cement subbase, known as an inverted pavement, provided better performance than the soil cement bases and resisted rutting and retarded the occurrence of reflection cracking. This finding confirmed results from other research conducted previously. On the basis of the analysis, it is recommended that an inverted pavement section definitely be considered for use in Louisiana even in those areas where the subgrade is relatively soft. In addition, soil cement bases of 4 percent cement and mixed in place should be constructed and their performance observed and compared with that of the more standard 10 percent mixed-in-place soil cement bases.
Accident Reduction Effects of Using Weigh-in-Motion and Automatic Vehicle Identification for Mainline Bypass Around Truck Weigh Stations
Authors: Barnett Jeffrey C. , Benekohal Rahim F.
Published: April 2007

Using weigh-in-motion (WIM) and automatic vehicle identification (AVI) technologies may permit trucks with appropriate credentials to bypass the weigh station on the mainline traffic stream. This would reduce the number of disruptions to the mainline traffic stream and reduce the chances that an accident might occur. Characteristics of accidents on road segments around weigh stations [influence zones (IZs)] are examined and compared with those for accidents on similar basic freeway sections [control zones (CZs)]. There were significantly more accidents around weigh stations than on similar basic freeway sections, particularly during operating hours. Similarly, there were significantly more accidents involving trucks in the IZs than in the CZs. A comparison of the number of IZ and CZ accidents during typical operating hours, excluding animal-related accidents, indicated that the CZs had 38 percent fewer accidents than the IZs. This would result in 146 fewer accidents during typical operating hours around the 20 Interstate weigh stations when animal accidents are not included. When animal accidents were included, the reduction was 30 percent. This would reduce the total number of accidents during typical operating hours around the 20 Interstate weigh stations over 10 years by 129. Thus, a maximum reduction of 129 to 146 accidents could be achieved if the IZs were made identical to the CZs. These figures represent the upper limit of accident reductions. A model is developed to predict potential accident reductions around weigh stations at varying levels of WIM and AVI usage. The resulting model is an S-shaped curve, which should approximate the potential accident reductions as a function of percent WIM-AVI usage.
Decision Aids for Tunneling
Authors: Einstein Herbert H. , Indermitte Claude , Sinfield Joseph , Descoeudres Françcois P. , Dudt Jean-Paul
Published: April 2007

The decision aids for tunneling (DAT) are a computer-based tool with which tunnel construction cost and time as well as required and produced resources can be computed. The DAT work with standard information such as geologic/geotechnical, structural, and material characteristics as well as construction performance. The two major components of the DAT, the “description of geology” and “construction simulation and construction management” are reviewed followed by descriptions of major applications of the DAT. Specifically, this involves application in the projects of two new transalpine rail tunnels in Switzerland (Gotthard, 57 km; Lötschberg, 36 km), investigation of different alternatives for a Metro project, and, finally, use of the DAT for assessing the effect of new tunneling technology on cost and time of construction.
Metal Culvert Response to Earth Loading: Performance of Two-Dimensional Analysis
Authors: Taleb Bahaa , Moore Ian D.
Published: April 2007

The results of finite-element analyses conducted before and after testing of a 9.5-m span low-profile metal arch culvert are presented here. A two-dimensional procedure that models the elastic-plastic response of both structure and soil during backfilling has been used. A plasticity-based procedure to provide an upper bound for the effect of soil compaction on metal culvert response during side filling is introduced and used in the analysis of field response. The procedure involves application of passive earth pressures after layer placement to simulate the highest values of residual horizontal earth pressure. The pretest and posttest analyses are compared with measurements of field response previously published by Webb et al. Predictions for culvert deformation and bending moments generated during backfilling were excellent. The new procedure to include the effects of compaction during construction was effective in capturing culvert peaking during placement of the side fill and increases in bending moment. Both pre- and posttest predictions for deformation and moment successfully captured the culvert response during burial and the effect of backfill soil density. The posttest predictions include consideration of the top-loading applied during placement of the side fill. The predictions of deflection follow measured values during application and subsequent removal of those temporary surcharge loads. Estimates of soil stresses acting normal to the external surface of the culvert were shown to be close to those measured in the field. The analysis indicates that shear strength is fully mobilized in wedge-shaped zones of the backfill adjacent to the culvert. Those zones diminish in size once backfill is placed over the crown. The residual horizontal earth pressures that are modeled during compaction act to reduce the size of the plastic zones.
Metal Culvert Response to Live Loading: Performance of Three-Dimensional Analysis
Authors: Moore Ian D. , Taleb Bahaa
Published: April 2007

A three-dimensional elastic procedure was used to examine the response of a 9.5-m span low-profile metal arch culvert to surface live load. Field tests featured a heavily loaded truck producing axle forces at conventional design limits. Culvert response was measured and analyzed at very low cover. The three-dimensional finite-element analysis for vehicle load provided good predictions of the magnitude and distribution of culvert deformations. Predictions of moment and thrust were reasonable, but the analysis neglects shear failure in the soil and this likely produced moments and thrusts directly under the wheel loads that were less than the field measurements. Three-dimensional analysis with backfill modulus reduced to compensate for the effect of shear failure in the soil below the vehicle produced thrust and moment values close to those measured in the field. A comparison with two-dimensional predictions of culvert response to live load revealed the importance of explicitly modeling the three-dimensional geometry of the vehicle. Plane-strain analysis with line-load equivalents, which give close to the correct crown deflection, produced thrust and moment estimates that were in error by factors of 9 and 3, respectively.
Curved-Beam Stiffness for Thermoplastic Gravity-Flow Drainage Pipes
Authors: Gabriel Lester H. , Goddard James R.
Published: April 2007

Procedures for evaluating time-independent initial stiffness, at the time of application of load, of high-density polyethylene and polyvinyl chloride gravity-flow drainage pipes with curved-beam sections of production run pipe are proposed as an alternative to ASTM Standard D2412 “Test Method for Determination of External Loading Characteristics of Plastic Pipe by Parallel Plate Loading.” A strategy for predicting relaxation moduli extrapolated to 50 and 100 years is proposed. Laboratory studies are presented and discussed.
Full-Scale Field Tests on Longitudinal Uplift Response of Corrugated Metal Pipe
Authors: Kjartanson Bruce H. , Lohnes Robert A. , Klaiber F. Wayne
Published: April 2007

In response to problems with corrugated metal pipe (CMP) culvert uplift failures caused by unbalanced inlet hydraulic loading, full-scale field testing and numerical analysis were undertaken to develop a rational design methodology for CMP inlet tiedowns. Four uplift tests performed on a 2.44-m-diameter CMP under different backfill cover, foreslope, and restraint conditions are described. The objectives of the tests were to gain insight into the soil-structure interaction processes and to provide data for verification of the performance of the finite-element model used to calculate the required restraint forces. The test results indicate that the backfill foreslope has a significant effect on uplift response. For example, the force required to lift the CMP inlet 25 mm was about 50 percent greater with 0.6 m of backfill cover and a full 2:1 foreslope than with 0.6 m of backfill cover and approximately 4 m of the CMP exposed beyond the toe of the backfill foreslope. These results indicated that appropriate modeling of the soil-structure interaction and interface behavior in the foreslope region is extremely important.
Scrap Tire Culverts: Hydraulics and Design
Authors: Yang Shiping , Kjartanson Bruce H. , Gu Ruochuan , Lohnes Robert A.
Published: April 2007

Reusing whole scrap tires as a culvert is a cost-effective alternative to draining water from small drainage basins. The complete design of a scrap tire culvert must consider both structural and hydraulic performance. Hydraulic considerations are the focus of this report. The hydraulic capacity of a scrap tire culvert is largely affected by the limited size and the relatively rough barrel formed by scrap tires. In this analysis, the hydraulic capacities of culverts made of truck tires, at various slopes and lengths, were obtained by estimating Manning’s roughness coefficient and limiting the maximum flow depth in the culvert to 75 percent of the pipe diameter. The Manning’s roughness coefficient of a truck tire culvert was estimated to be 0.05 and 0.075, respectively, with and without sand ballast placed in the bottom of tires. The results show that a truck tire culvert can drain water up to 0.35 m3/s, and its hydraulic efficiency approaches that of conventional pipes of the same diameter when the slope is greater than 0.11 or 0.30, respectively, for culverts made of truck tires with or without sand ballast. The equivalent concrete and corrugated metal pipe sizes were obtained for corresponding flow capacities of truck tire culverts.
Construction of a Full-Scale Noise Barrier with Recycled Plastic
Authors: Roschke Paul N. , Esche Steven T.
Published: April 2007

The feasibility of using recycled plastics in place of conventional building materials in the design and construction of a prototype noise barrier is presented. A design process that allows selection of support columns that limit lateral deflection of the barrier due to wind load is introduced along with discussion that focuses on fabrication and installation of components of the prototype noise barrier. Analysis of the structure includes monitoring of response to environmental factors such as exposure to ultraviolet radiation and testing of acoustic insertion loss.
Traffic Capacity, Speed, and Queue-Discharge Rate of Indiana’s Four-Lane Freeway Work Zones
Authors: Jiang Yi
Published: April 2007

In addition to traffic capacity, vehicle speeds and queue-discharge rates at work zones are essential in assessment of work zone traffic delays and user costs. The traffic flow characteristics of freeway work zones were analyzed based on the traffic data collected from Indiana four-lane freeways. It was found that traffic congestion at work zones was characterized by sustained low vehicle speeds and fluctuating traffic flow rates. Therefore, work zone capacity was defined as the traffic flow rate just before a sharp speed drop, followed by a sustained period of low vehicle speed and fluctuating traffic flow rate. Study results indicate that the mean queue-discharge rates in Indiana freeway work zones were lower than the work zone capacities, even though, at times, individual values of queue-discharge rates could be higher than capacities. Therefore, it is not justified to use work zone capacity values, instead of queue-discharge rates, in estimating traffic delays and user costs under congested conditions. Vehicle speeds at work zones under uncongested conditions remained stable and close to the work zone speed limit of 88.5 km/h (55 mph), while they dropped 31.6 to 56.1 percent from the normal work zone speeds during congestion. The values of work zone capacity, queue-discharge rate, and vehicle speed provide valuable input for predicting traffic congestion, estimating traffic delays, and analyzing user costs at work zones.
A Model for Estimating Excess User Costs at Highway Work Zones
Authors: Jiang Yi
Published: April 2007

Highway work zones reduce available lanes for traffic, form traffic bottlenecks, and cause traffic delays and congestion. The additional travel time and effort involved in changing driving maneuvers at work zones result in excess costs to motorists in time, consumption of fuel and oil, and wear and tear of vehicle parts. A model for estimating excess user costs at work zones was developed based on traffic data collected at work zones on Indiana’s freeways. Indiana’s model for estimating excess user costs at work zones is described. Individual components of user costs and total user costs at two work zones were calculated to show the applications of the model. Factors affecting the work zone user costs are also discussed, and examples of application are included. Also briefly presented are the values of traffic capacities, average vehicle speeds, and queue-discharge rates of work zones.
Serious and Fatal Injuries to Workers on Highway Construction Projects
Authors: Bryden James E. , Andrew Laurel B.
Published: April 2007

An analysis of 240 accidents resulting in hospital-level or fatal injuries to workers on New York State Department of Transportation highway and bridge construction projects between 1993 and 1997 identifies types of accidents resulting in worker injuries. Construction accidents accounted for nearly four-fifths of all serious injuries and nearly three-fifths of the fatalities. Traffic accidents accounted for about one-fifth of the serious worker injuries and more than two-fifths of the fatalities. Construction accidents involving tools and equipment were most frequent, accounting for nearly half of the serious worker injuries and 20 percent of the fatalities. Fall accidents accounted for one-quarter of all serious construction injuries, with falls from heights the most common occurrence. Serious injuries from trench or excavation collapse and electrical contacts were rare, but electrical contacts resulted in two fatalities. Although not as frequent as construction accidents, traffic accidents also represented serious risk both to pedestrian workers and to workers in construction vehicles or equipment. Traffic accident injuries involving pedestrian workers accounted for 15 percent of all serious injuries and more than 40 percent of the fatalities. Two-thirds of the traffic accident injuries to pedestrian workers occurred from vehicles intruding into marked work spaces and striking workers or flaggers, but 4 of the 14 worker fatalities included in the study involved workers who were outside the defined work space. The calculated fatality rate of 24.4 fatalities per 100,000 worker years is higher than rates reported for workplace fatalities in general but is consistent with reported rates for construction occupations.
Application of Optical Speed Bars to Highway Work Zones
Authors: Meyer Eric
Published: April 2007

The proximity of workers and traffic makes safety a high priority in highway work zones. The occurrence and severity of accidents is related to vehicle speeds and speed variations. The use of optical speed bars to reduce speeds and speed variations in highway work zones is examined. Previous applications of this traffic control device are considered with respect to design parameters such as length of pattern, number of stripes, and the sequence of spacing between bars. A general design was developed to test the effect of the pattern on speed, the mechanism through which the effect occurs, and the usefulness of the technique to work zones (previous applications have been predominantly at the approach to intersections). Because the application of multiple-pattern designs is impractical, simulations of various designs were developed to obtain subjective evaluations of the relative effectiveness of the various alternatives. Based on the review of previous applications and the subjective evaluations, a pattern design was developed. The design process is delineated and the resulting design described. Also described are adaptations that were made to previous designs specifically for the application of the technique to highway work zones. Finally, a test project to measure the effect of the technique on traffic is described.
Reflective Properties of Selected Road Surfaces for an Automobile Headlamp Geometry
Authors: Schnell Thomas , Zwahlen Helmut T. , Smith Ryan
Published: April 2007

Luminance-contrast-based pavement marking visibility models are widely used in the design of street and automobile lighting systems, the design and evaluation of retroreflective sheeting materials and pavement-marking materials, and in the establishment of minimum visibility requirements for nighttime motorists. Computer-based visibility models usually determine the visibility of pavement markings by comparing the available luminance contrast formed between the pavement marking and the immediate surrounding road surface with a human threshold contrast value. However, to be able to calculate the luminance contrast between a pavement marking and the road surface, a pavement-marking visibility model needs matrices of retroreflectance as a function of the entrance angle and the observation angle, both for the pavement and the pavement markings. However, no extensive field data are available on the reflective properties of road surfaces under an automobile headlamp geometry (observation angles less than 1°). Retroreflectance matrices were developed for old asphalt, new asphalt, old concrete, and new concrete road surfaces. The road surface retroreflectance was measured with a specially designed apparatus in the field. Multiple linear regression models were developed with the retroreflectance data obtained for each measured road surface. Traffic sign luminance measurements under automobile headlamp illumination conditions were conducted in the field at night to determine the degree to which a post-mounted traffic sign (sign center 1.98 m above the ground) receives indirect light reflected from the road surface.
Location and Configuration of Passing Lanes
Authors: Mutabazi M.I. , Russell E.R. , Stokes R.W.
Published: April 2007

Kansas State University conducted a study of passing lanes on major two-lane highways in Kansas. Passing lane location and configuration are among the crucial design factors that may affect the operation and safety of two-lane highways containing passing lanes. The literature suggests that passing lanes should not be located where crossroad intersections exist. Yet a traffic conflict study of Kansas passing lane locations found that the mean traffic conflict level at crossroad intersections located within the passing lane was lower than it was at a similar intersection on a two-lane highway outside the passing lane sections. Crossroad intersections may be tolerated within passing lanes if they are not in the laneaddition and lane-drop areas of the passing lane and if turning volumes are relatively low. Based on traffic simulation, there was no evidence that tail-to-tail passing lane configurations are better than other configurations, as claimed in the literature. However, the difference in percent time delay between different passing lane configurations was found marginal from a practical point of view.
Relationship to Safety of Geometric Design Consistency Measures for Rural Two-Lane Highways
Authors: Anderson Ingrid B. , Bauer Karin M. , Harwood Douglas W. , Fitzpatrick Kay
Published: April 2007

The relationship of safety to five candidate measures of geometric design consistency for rural two-lane highway alignments was examined. The measures that were evaluated included: ( a) speed reduction on a horizontal curve relative to the preceding tangent or curve, ( b) average radius, ( c) ratio of maximum radius to minimum radius, ( d) average rate of vertical curvature, and ( e) ratio of individual curve radius to average radius. All of these measures were found to have statistically significant relationships to accident frequency in the direction expected and are recommended as candidate measures for assessment of geometric design consistency. The relationships between design consistency measures and accident frequency were developed using Poisson, negative binomial, and lognormal regression analysis.
Distribution of Roadway Geometric Design Features Critical to Accommodation of Large Trucks
Authors: Harwood Douglas W. , Glauz William D. , Elefteriadou Lily , Torbic Darrin J. , McFadden John
Published: April 2007

The ability of the roadway system to accommodate large trucks is constrained by the geometric design of key features, including horizontal curves, interchange ramps, interchange ramp terminals, at-grade intersections, and steep grades. The distribution of the dimensions of roadway elements that are critical to accommodation of larger trucks on the highway is shown, including horizontal curves and grades on mainline roadways, horizontal curves on interchange ramps, and curb return radii for at-grade ramp terminals and intersections. Frequency of mainline and ramp curves with very sharp radii and of very steep mainline grades was found to be very limited. For example, only about 5 percent of interchange ramps have horizontal curves with radii of 30 m (100 ft) or less, and approximately 20 percent of rural ramps and 30 percent of urban ramps have radii of 75 m (250 ft) or less. Curb return radii less than or equal to 12 m (40 ft) on which trucks would frequently encroach are more frequent. Curb returns with sharp radii are more prevalent in urban than in rural areas and are more prevalent at intersections than at ramp terminals.