California Department of Transportation

About: California Department of Transportation is a government organization based out in Sacramento, California, United States. It is known for research contribution in the topics: Poison control & Seismic analysis. The organization has 308 authors who have published 389 publications receiving 12623 citations. The organization is also known as: Caltrans & Bureau of Highways.

Predicting Geotechnical Parameters of Sands from CPT Measurements Using Neural Networks

Abstract: This study develops a system of neural networks for predicting sand parameters such as relative density, coefficient of lateral earth pressure at rest and overconsolidation ratio, based on cone penetration test (CPT) measurements. The proposed system uses backpropagation neural networks for function approximation and probabilistic neural networks for classification. By strategically combining both types of networks, the proposed system is able to predict the sand and other soil parameters accurately without iterative procedures. Being able to estimate the coefficient of lateral earth pressure at rest and overconsolidation ratio is significant because no other CPT-based methods exist that can produce accurate and consistent estimates of these parameters.

Fracture critical inspection team of the State of California Department of Transportation

Abstract: The Department of Transportation for the State of California (Caltrans) abides by the regulations of the Federal Highway Administration's National Bridge Inspection Standards section 650.305 that states that bridges are to be inspected at regular intervals not to exceed two years. The Division of Structures, Office of Structures Maintenance and Investigations is responsible for the inspection of approximately 26,000 bridges in California. Approximately 3,100 of these are steel bridges and of these, 1,000 have fracture critical members. Fracture critical members are tension members of a bridge whose failure will probably cause a portion of, or the entire bridge, to collapse. In 1980, the Division of Structures established a category 'A' inspection program which identified what fracture critical features were on the steel structures. All of the 'ingredients' are present for steel structures to develop cracks. The age of the structures has increased along with the average daily truck traffic and their loads. The material properties required in the 1950s and 1960s did not have requirements for fracture toughness. Proper welding procedures/quality remain a challenge to achieve today, and those structures that are 30 to 40 years old were not immune to this problem. Caltrans has 12 districts in the state with at least two area bridge maintenance engineers (ABME) per districts. Caltrans requires that the ABME be a licensed civil engineer. The ABME faces a heavy responsibility when inspecting fracture critical members. The ABME is not trained in different methods of nondestructive evaluation (NDE), which is not unusual for an engineer graduating from a four-year engineering curriculum. Beginning in 1985, the Welding and Metals Technology Branch of the Transportation Laboratory assisted the Division of Structures in the inspection of these fracture critical features using NDE methods. As of 1990, the Welding and Metals Technology Branch's Fracture Critical Inspection Team accompanies AMBEs on their scheduled category 'A' inspections.© (1995) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Automated Sequence Selection and Cost Calculation for Maintenance and Rehabilitation in Highway Life-Cycle Cost Analysis (LCCA)

Abstract: Life-Cycle Cost Analysis (LCCA) for highway projects is an analytical technique that uses economic principles to evaluate long-term alternative investment options, especially for comparing the values of alternative pavement design structures and construction strategies. Several approaches and software have been adopted to undertake LCCA by many transportation agencies in the United States over the last decade. In 2007, the California Department of Transportation (Caltrans) adopted RealCost, the LCCA software, developed by the U.S. Federal Highway Administration (FHWA). The California implementation incorporates major user interface enhancements and customization. This paper introduces the Caltrans LCCA procedure and describes the functions and improvements of the enhanced California version of RealCost software (RealCost 2.5CA). Automated functions were developed to select efficient and adequate sequences for future maintenance and rehabilitation (M&R) for comparing alternatives. The graphical user interface integrates service life, maintenance frequency, and agency cost of each maintenance activity with given project constraints, such as climate region, final pavement surface, and design life. The automated cost calculation modules estimate future M&R costs based on each construction scope and pavement type. The main focus of the California LCCA enhancement is to improve the efficiency of LCCA procedures with automatic data selection and computations. The RealCost 2.5CA program has been adopted as an official LCCA tool to comply with regulatory requirements for California state highway projects. Utilization of this California-customized LCCA software helps Caltrans to achieve substantial economic benefits (agency cost and road user cost savings) for highway projects.

Stress-Strain Behavior of Geomaterials in Loading Reversal Simulated by Time-Delay Neural Networks

Abstract: The effectiveness of time-delay artificial neural networks (TDANNs) as highly nonlinear mapping tools for simulation of hysteresis stress-strain (σ-e) response of geomaterials under repeated reversal loading is investigated. A nonlinear recursive simulator containing the developed TDANNs was designed to enable forecasting of complete σ-e curves from the knowledge of only the initial σ-e condition of the tested material. Theoretically-obtained data were used to derive the TDANNs, and simulations were performed to validate the proposed approach. Advantages, limitations, and method of enhancement of the approach are presented.

Plantable geosynthetic reinforced retaining wall

Abstract: A modular retaining watt has tiers of headers which extend into compacted backfill material and tiers of stretchers which extend between headers to form the front face of the wall. Vertical pins, extending between successive headers in each stack of headers, facilitate precise emplacement of headers during construction of the wall. Layers of geosynthetic mesh reinforcement reinforce the load bearing capability of the backfill. Load forces in the backfill are sustained by forward ends of the layers of geosynthetic mesh reinforcement, which extend upward in front of the backfill and then backward into the backfill, instead of being sustained by the stretchers. A sizable space behind the stretchers may be filled with loose topsoil to facilitate growth of landscaping plantings on the face of the wall.