Displaying Records 1-10 of 19840
|Light Detection and Ranging (LIDAR) Deployment for Airport Obstructions Surveys
Obstructions surveys--the identification and mapping of objects on the ground that might interfere with aircraft operations--are required at all airports. These surveys are used by the airport to analyze when action is needed to avoid or remediate impingements on airspace (e.g., reduce the height of trees near runways); by airlines to analyze flight paths for their aircraft; and by the Federal Aviation Administration (FAA) to analyze and design new instrument approaches, including global positioning system (GPS) approaches. Airports also use these surveys to update airport layout plan (ALP) drawings that may become the basis for restricting the heights of structures that could impinge on airspace and to note locations of temporary potential obstructions (e.g., construction cranes). The National Oceanic and Atmospheric Administration's (NOAA) National Geodetic Survey (NGS), operating under a series of interagency agreements with the FAA, is responsible for certifying that information developed from obstructions surveys meet the requirements for operation of the National Airspace System. Obstructions data collected and information derived from those data for ALP development may go beyond NGS-administered requirements. Most obstructions-survey data are obtained using field-survey and photogrammetric methods. A traditional NOAA-certified obstruction survey takes approximately 6 months, and a backlog of demand for such surveys far exceeds the funding available under federal programs, so that some airports must operate with obsolete and possibly inaccurate obstructions information. In addition, introduction of new GPS approaches at airports has increased demand for obstructions-survey data and lack of resources for obstructions surveys impedes FAA's ability to support this new technology. Seeking to reduce costs and enhance accuracy of obstructions surveys, the FAA and NOAA have been conducting research on the use of airborne LIDAR technology. This research has proven that airborne LIDAR data can be used effectively in analysis and mapping of obstructions, including treetops and poles, accurately. Now that use of airborne LIDAR data has been proven technically effective for obstruction analysis, further research is needed to establish a cost-effective methodology that airports and their consultants can adopt to procure, process, and use these new data. The objectives of this research are (a) to describe requirements that must be met to use LIDAR data in aeronautical obstructions surveys and airport layout plan (ALP) elevation surveys; (b) to recommend procurement specifications and procedures that could be used by airports or other agencies for procuring and using LIDAR data; and (c) to describe the technical bases that could justify acceptance of LIDAR-based obstructions surveys by the NGS, FAA, airports, and airlines.</p>
FAA, USD350,000.00, Completed
|Increased Understanding of Driver Visibility Requirements
This research project will develop a hybrid human/computer model of the quantity and quality of visual information needed to navigate certain curves in the roadway safely and effectively at night.
FHWA, USD1,309,272.00, Completed
|Ramp Incident Data from Selected Large and Medium Hub Airports
|Flexural Fatigue Performance of an Ultra-High Performance Concrete
Recent advances in concrete materials have led to a new generation of cementitious materials, namely ultra-high performance concrete (UHPC). This concrete possesses advanced properties in terms of compressive behavior, durability, and tensile load carrying capacity. UHPC attains these behaviors via an optimized gradation of cementitious materials, chemical admixtures, and steel fiber reinforcement. The current project aims to investigate the tensile fatigue behavior of this type of concrete through the flexural testing of 18 medium scale prestressed rectangular beams. In this test program, the cyclic load levels will focus on the cracking strength of the UHPC so as to allow for the determination of the steel fiber reinforcement behaviors under fatigue loading.
|Foundation Health Monitoring Systems
A series of field investigations are underway to demonstrate foundation monitoring systems and utilize data for enhanced engineering assessment of structural performance. The new I-35W bridge in Minneapolis and the Woodrow Wilson Bridge in Virginia are current test sites.
|NDGPS Reference Station Modernization
This project involves research to define existing global positioning system capability area.
|Evaluation of Preventive Maintenance Treatments
Preventive maintenance is the planned treatment of pavements that provides protection, decreases the rate of deterioration and adds 5 to 10 years to the service life of the pavement. Agencies must determine which of the many treatments that are available provides the most benefit for the various stages of a pavements life. In this study an evaluation will be performed of two seal treatments to provide cost/benefit data and assist in the updating of Mississippi DOT?s ?decision trees? that are utilized to determine which preventive maintenance treatment provides the most benefit for each pavement condition.
FHWA, USD90,000.00, Completed
|Countermeasures to Reduce Big-Rig Crashes
The Arizona Department of Transportation's (ADOT?s) Motor Vehicle Division reported that trucks (large and small) constitute 27% of vehicles involved in crashes and 30% of fatal crashes. Although big-rig crashes are less frequent than those involving passenger cars, their impact on fatality and traffic congestion are far greater than passenger car related crashes. Hence, countermeasures to reduce big-rig crashes are crucial from the safety and congestion management standpoint. The objectives of this research are to identify freeway segments in Arizona with high frequencies of big-rig crashes and to develop countermeasures to reduce the probability of incident occurrence.
FHWA, USD100,000.00, Active
|Low-Cost Energy Dissipation at Culvert Exits
Many culverts in Nebraska require a steeply sloped section in order to convey water to the downstream side of the roadway. The resulting high velocities in the culvert barrel are mitigated by a hydraulic jump in some circumstances, but in many others the high velocities must be diminished by some kind of energy dissipation. Energy dissipation at box culvert outlets is important for reducing harmful impacts to the receiving channel and for minimizing soil loss through scour and erosion. Currently the only options available to roadway designers are riprap basins or rigid concrete structures requiring significant additional costs for concrete and steel and right-of-way. It is proposed to evaluate at least three different energy dissipating methods for concrete box culverts: a sill wall placed in the downstream apron of the box culvert, a vertical drop structure with stilling pool or sill, and the feasibility of using concrete forms to increase the hydraulic roughness of the interior walls and floor of a concrete box. The idea for the sill wall and drop structure are that they will act to trip a hydraulic jump within the concrete barrel and reduce its outlet velocity. The idea for increasing the hydraulic roughness of the interior of the box is to keep the velocity from getting high enough that energy dissipation is necessary. The proposed research project will be a joint research project between the University of Nebraska ? Lincoln, Washington State University, the Nebraska Department of Roads (NDOR), and the Federal Highway Administration (FHWA). The goal of the research is to experimentally evaluate several simple, low-cost alternatives for dissipating the energy in rapidly moving water exiting from culverts and to incorporate successful methods into NDOR design procedures.
FHWA, USD106,979.00, Completed
|Evaluate Warm Mix Technology for use in Asphalt Rubber - Asphaltic Concrete Friction Courses (AR-ACFC)
European countries are using technologies that allow a reduction in the temperatures at which asphalt mixes are produced and placed. These technologies have been labeled Warm Mix Asphalt (WMA). The immediate benefit to producing WMA is the reduction in energy consumption required by burning fuels to heat traditional hot mix asphalt (HMA) to temperatures in excess of 300? F at the production plant. With the decreased production temperature comes the additional benefit of reduced emissions from burning fuels, fumes, and odors generated at the plant and the paving site. The technology allows the production of WMA by reducing the viscosity of the asphalt binder at a given temperature. This reduced viscosity allows the aggregate to be fully coated at a lower temperature than what is traditionally required in HMA production. There have been a number of demonstration projects in the US with a variety of mixes and binders, but none with asphalt rubber. This will be a two-phase project to evaluate the applicability of warm mix asphalt technology to Arizona Department of Transportation (ADOT's) AR-ACFC mixes. The first phase would be principally a laboratory evaluation and review of relevant literature designed to answer the following questions: Are the existing WMA technologies compatible with the asphalt rubber binders used in ADOT's AR-ACFC mixes? How does ADOT's design procedure for AR-ACFC mixtures need to be modified to accommodate WMA technologies? The second phase would be primarily a field trial with the following research objectives: (1) to characterize (quantify) the potential plant production / mix lay-down savings that can be generated by using WMA technologies in AR-ACFC (e.g. energy cost reduction, reduced emissions, etc.); (2) to characterize the impact of incorporation WMA technologies into AR-ACFC mixes on the surface characteristics of the mix (e.g. noise reduction capabilities, frictional characteristics, and smoothness); and (3) to evaluate the potential for extension of the paving window for AR-ACFC resulting from reduced paving temperatures (e.g. minimum surface temperature, paving season).
FHWA, USD155,000.00, Active