Transportation Research Record: Journal of the Transportation Research Board

A new link road is to be constructed top down between parallel cast-in place pile walls under a series of railway lines in Kreuzlingen, Canton Thurgau, which is an important hub in the regional transportation network. The results of a site investigation on the soft, normally consolidated, post-glacial lacustrine clay deposit underlying the railway lines, including a cone penetration test, undisturbed sampling from an adjacent borehole, and laboratory testing, are reported. Strength characteristics of the clay were determined, correlated, and linked to stress history and current stress. The investigation demonstrated a close agreement between strength parameters derived from the laboratory and the in situ testing when a piezocone factor of N_kT = 17 was applied. This agreement confirms previous local experience. The results obtained lead to a more differentiated knowledge of the clay deposit, providing valuable data for constitutive modeling. These data will be particularly useful for future local construction work using the observational method and value engineering.

A stratum of cemented sand can cause numerous geotechnical design problems. Extensive research has been conducted to determine both the properties of cemented sand and their effects on the engineering response of soil. A cone penetration test module was developed at the University of Florida to detect the presence and strength of these materials. After design and construction were complete, the prototype module was field tested in sand without cementation and again at a site with possible cementation. Development, calibration, and field testing of the module are discussed, as are preliminary recommendations for its potential use.

Driven piles are a common foundation used to support highway bridges. Data gathered from instrumented piles and piezocone tests in finegrained soils indicate that variable pore pressure profiles, which depend on the overconsolidation ratio of the soil, can develop during penetration. For piles driven in soft clays and silts, the pore pressure profiles developed show a monotonically decreasing response with time. However, for piles driven in heavily overconsolidated silts and clays, the pore pressure profiles show dilatory behavior, with the pore pressure behavior increasing from the initial measured value to a maximum, and then decreasing to hydrostatic values. A theoretical framework is presented that combines cavity expansion theory and critical state soil mechanics with an analytical solution to the radical consolidation equation to estimate the pore pressure response as a function of time and to evaluate the coefficient of consolidation of fine-grained soils on the basis of instrumented pile and piezocone data. The method is able to describe the pore pressure response curve in soils that demonstrate either monotonically decreasing or dilatory pore pressure behavior. Driven pile data from three sites are used to verify the estimations of the model.

Results of a case study to demonstrate the use of the piezocone (CPTU) for selection of soil parameters for design of bridge foundations at a clay site in Massachusetts are presented. The test site is the location of several timber-supported bridges that have suffered significant deck and foundation deterioration and need replacement. The soil profile generally consists of 1 to 10 m of fine sand and silt, followed by 45 m of a low-plasticity marine clay that rests on a very dense fine to coarse sand. The site investigation consisted of traditional drilling and sampling techniques, field vane testing, and CPTU profiling. Shelby tube samples were used for laboratory tests, including basic soil characterization and measurements of stress-strain-strength behavior through oedometer and K₀ consolidated direct simple shear tests. Results from laboratory tests showed that some of the tube samples had suffered moderate to high levels of sample disturbance, making them unreliable for laboratory stress-strain-strength testing. A comparison of the laboratory results with the CPTU profiles showed that the CPTU provided excellent information on soil stratigraphy and good comparison with the laboratory-determined stress history and undrained shear strength profiles. The CPTU test program involved less time and expense than the laboratory test program and was not susceptible to sample disturbance effects. This case study suggests that state departments of transportation should consider the CPTU as the instrument of first choice in site characterization programs for design of bridges founded on soft clays.

A comparison of four different methods for predicting the axial compression capacity of single piles using cone penetration test (CPT) results is presented. Nineteen pile load tests and parallel CPT soundings conducted close to the piles were identified and documented from the Louisiana Department of Transportation and Development archives. Piles with different sizes and lengths were investigated. The four prediction methods selected were the Schmertmann method, the de Ruiter and Beringen method, the French Central Bridge and Pavement Laboratory (LCPC) method, and the Tumay and Fakhroo method. An evaluation scheme was performed using these methods to assess their capability to reliably predict the axial compression capacity of piles installed in soft Louisiana soils. The predicted pile capacities obtained by the different methods were compared with the measured pile capacities obtained from pile load tests. Analysis of the results showed that the Schmertmann, de Ruiter and Beringen, and Tumay and Fakhroo methods predicted the ultimate compression capacities of piles installed in soft Louisiana soils with a reasonable accuracy. The LCPC method underpredicted the measured capacities of these piles.

Nine axial pile load tests were performed in connection with the reconstruction of I-15 through Salt Lake Valley, Utah. In addition, load test data were collected for seven other piles in the valley. The soil profile at these test sites generally consisted of saturated soft to medium stiff silts and clays underlain by a dense sand bearing stratum at 25 to 30 m. Test piles consisted of closed-end steel pipe piles 300 to 600 mm in diameter with a concrete fill. Because cone penetration soundings were available for 15 of these test piles, these data were used to evaluate the accuracy of five available design methods that are based on cone penetration testing. Methods evaluated were the Dutch, Schmertmann, Tumay, Laboratoire des Ponts et Chaussées (LPC), and Fellenius methods. The Davisson method was used to define ultimate capacity. For most design methods, the estimated skin friction was on average only 40 to 60 percent of the measured resistance. The Dutch method predicted 82 percent of measured skin friction, on average, but still exhibited significant scatter for individual tests. Underprediction of skin friction by the LPC method was caused by unnecessarily severe restrictions for steel piles. Without these restrictions, the standard error was cut in half and estimated capacity was 96 percent of the measured capacity, on average. The LPC method also provided the best match with measured end bearing resistance (within 11 percent on average), whereas other methods overestimated capacity by 60 to 80 percent. Overall, the LPC method without side friction limitations gave 97 percent of the measured capacity on average and had the lowest standard error of any of the methods.

Petroleum products are composed of many organic chemicals and are recognized as the most prevalent contaminants found in contaminated soils and sediments. Of particular regulatory interest are simple aromatics and polycyclic aromatic hydrocarbons, which are toxic and carcinogenic at low levels. Many treatment processes have been used for treatment of fuels. Biotreatment appears to hold the most promise as a cost-effective process that can destroy petroleum hydrocarbons on site. The potential for bioremediation was evaluated on a soil contaminated with heavy motor oil from years of dumping waste oils from an automotive garage. This soil was selected because it posed a unique challenge to bioremediation and therefore provided the framework for evaluation of various process enhancements. A series of shake-flask experiments (500-mL flasks filled with 25 percent w/w water-soil slurries) was performed to determine the extent and rate of removal of total petroleum hydrocarbons (TPH) using various soil amendments, including nutrients, cometabolites, a nonionic surfactant, and microbial seeds. The information from the shake-flask experiments was used to plan a series of experiments that used eight 30-L (8-gal), bench-scale biocell reactors. The results of the biocell experiments show that approximately 80 percent of the TPH could be removed using a treatment system that consisted of nutrient and surfactant amending with bioaugmentation with activated sludge.

For two decades, designers of railway systems worldwide have found Reinforced Earth to be ideally suited for support of track beds and bridge and trestle abutments, for earth retention structures adjacent to rights-of-way, and for deflection walls to protect bridge piers from impact in the event of derailment. Stray currents from direct current traction power railways have been shown to be of little concern in corrosion of the metallic soil reinforcements used in Reinforced Earth structures. The discrete metallic reinforcements used in Reinforced Earth structures lack electrical continuity, so the reinforcements act as individual short length conductors instead of part of a continuous network. Therefore, there is no tendency for stray currents to collect on individual reinforcements, accumulate as a result of electrical continuity, and discharge to the earth at remote locations. Select backfill that conforms to the standard mechanical and electrochemical requirements for Reinforced Earth structures provides additional resistance to the flow of stray currents. Several examples of the performance of galvanized reinforcing strips in stray current situations are provided. It is noted that galvanized steel reinforcements without a cathodic protection system have been the predominant choice since 1990.

Quality control of the compaction process is an important concern for owners and contractors because compaction is essential for improving the stability and density of construction materials such as soils and asphalt. When other conditions such as roller frequency, wheel load, and compactor speed are the same, the density of asphalt pavement depends on the number of coverages of the compactor. If the mat is compacted with less than the determined number of passes, the result may be a large volume of air voids, leading to low density. However, if the mat is overly compacted, the aggregates will be crushed further and the attributes of the mix will be changed, leading to a reduction in density. For this reason, monitoring the exact number of coverages over the entire surface of the pavement mat is desired. Research that started 3 years ago to develop an automated system for mapping compaction equipment using global positioning system (GPS) technology is reported. The objective of this research is to test the GPS receiver under various conditions of compaction operations. The researchers conclude that the accuracy of GPS devices selected should be better than 15 cm, the typical asphalt coverage overlap.

Data exchange, sharing, and archiving are universal problems for departments of transportation (DOTs) and the consulting industry. Unlike computer-aided design, for which translators have been in place for years, engineering data lack universal standards to enable electronic exchange. The lack of standards means that the civil and transportation engineering data are proprietary. Thus, in most cases, manual transcribing is required to share data from division to division or from department to consultant. In addition, archiving this information puts the DOT at risk of not being able to use this information in the future. A consortium of DOTs, consultants, and vendors was formed in June 1998 to define, document, prototype, and disseminate standard engineering data formats. This nonproprietary file format, Engineering and Survey-Exchange (EAS-E), will enable vendors to provide importing and exporting engines within their proprietary software products that will survive the test of time. EAS-E will foster a more efficient project work flow by DOTs, surveyors, design consultants, owner’s construction staff, and construction contractors. The data of primary interest are horizontal alignments, vertical alignments, coordinate geometry, cross sections, and surface data. Suggested formats for these data are presented.

The development of individual intelligent transportation systems (ITS) that operate well independently is not sufficient to meet the growing transportation needs of urban areas. To realize the true potential of ITS, systems such as freeway management systems, transit scheduling and dispatch systems, signal control systems, emergency computer-aided dispatch systems, and even construction scheduling systems must be integrated to allow for coordinated regional decision making. The formidable task of realizing integrated ITS (IITS) must often be accomplished by various municipal systems, most with little or no automation, and several organizational bodies that attempt to coordinate these efforts into a comprehensive regional network. Each of these organizations and systems has its own set of objectives, and these objectives may be noncommensurate and conflicting. Regional integration allows the systems to share information, allowing transportation officials to manage the entire regional transportation system. A sound regional architecture must be developed to guide developers in fitting their individual systems into a regional context. An overview of a vision of IITS is presented, along with an example of an integrated system proposed for the Hampton Roads region of Virginia. The vision is based on a critical analysis of five principal design areas: regional architecture, open systems, the World Wide Web and extranets, data warehousing, and data mining.

The categorization and quantification of the type, severity, and extent of surface distress is a primary method for assessing the condition of highway pavements. Several methodologies are reviewed that were developed to automate pavement distress surveys. Existing available applications of automated pavement surface distress surveys rely on analog video technology, which poses several limitations on the performance of the systems. Through the use of new digital, high-performance cameras, high-definition images of pavement surfaces were acquired. These images were directly captured, archived, and analyzed by microcomputers. Two types of digital cameras were used in the research: area scan and line scan. Research revealed that high-performance area scan cameras may have advantages over line scan cameras. However, line scan cameras based on the technique of time delayed integration have good potential when tight synchronization and correct timing control are fully integrated into the system. The imaging subsystem of a full digital highway data vehicle that has been developed at the University of Arkansas is also discussed.