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Federal Way, WI, United States

Hong S.,Korea Institute of Construction Technology | Vonderohe A.P.,Vonderohe Consulting LLC
Sensors (Switzerland)

Uncertainty and sensitivity analysis methods are introduced, concerning the quality of spatial data as well as that of output information from Global Positioning System (GPS) and Geographic Information System (GIS) integrated applications for transportation. In the methods, an error model and an error propagation method form a basis for formulating characterization and propagation of uncertainties. They are developed in two distinct approaches: analytical and simulation. Thus, an initial evaluation is performed to compare and examine uncertainty estimations from the analytical and simulation approaches. The evaluation results show that estimated ranges of output information from the analytical and simulation approaches are compatible, but the simulation approach rather than the analytical approach is preferred for uncertainty and sensitivity analyses, due to its flexibility and capability to realize positional errors in both input data. Therefore, in a case study, uncertainty and sensitivity analyses based upon the simulation approach is conducted on a winter maintenance application. The sensitivity analysis is used to determine optimum input data qualities, and the uncertainty analysis is then applied to estimate overall qualities of output information from the application. The analysis results show that output information from the non-distance-based computation model is not sensitive to positional uncertainties in input data. However, for the distance-based computational model, output information has a different magnitude of uncertainties, depending on position uncertainties in input data. © 2014 by the authors; licensee MDPI, Basel, Switzerland. Source

Vonderohe A.,Vonderohe Consulting LLC | Zogg J.,Bureau of Project Development | Whited G.,University of Wisconsin - Madison | Brockman K.,Wisconsin Department of Transportation
Transportation Research Record

The Wisconsin Department of Transportation (DOT) has developed a specification for highway subgrade construction by automated machine guidance (AMG). Wisconsin DOT is also deploying new design software, capable of providing three-dimensional (3-D) models required for AMG. During 2008, Wisconsin DOT, with assistance from the Construction and Materials Support Center at the University of Wisconsin-Madison, undertook a study of benefits and impediments to wider use of 3-D information in design and construction. The primary finding of a stakeholder workshop was that 3-D design and AMG are among a larger group of technologies and processes that have interrelated dependencies, synergistic benefits, and shared implementation issues. Thus, the study's objective was expanded to development of a high-level implementation plan for 3-D technologies and methods, in general, for highway design and construction in Wisconsin. The plan presents a vision, a management strategy, and six initiatives, including descriptions of backgrounds, issues, stakeholders, recommendations, goals, timelines, levels of effort, priorities, benefits, relationships with other initiatives, and responsible parties. The initiatives address an ongoing height modernization and continuously operating reference station program; standards, procedures, and training for 3-D data collection; 3-D model content and format standards; additional specifications for AMG; field technology and inspection; and infrastructure life-cycle uses of 3-D data. The plan differentiates between priorities (importance) and precedence (dependencies) among initiatives and goals within them. This information should be beneficial to other state highway agencies considering implementation of 3-D technologies. Source

Hintz C.,University of Wisconsin - Madison | Vonderohe A.P.,Vonderohe Consulting LLC
Transportation Research Record

Modern technologies for data collection, data processing, and highway design allow for accurate representation of terrain-specific information to support volume computations for earthwork. These technologies support the representation of existing ground, design, and final as-built surfaces that can be overlaid and differenced to obtain volumes. However, most state highway agencies still use, or even specify, the average-endarea method, which relies on a coarse abstraction of cross sections. Results of an investigation of three highway design and construction data sets indicated, as expected, that when the cross-section interval was decreased, average-end-area volumes approached those computed by the surfaceto-surface method. There could be exceptions, explainable by coincidence of the arbitrary cross-section interval and random variability of the terrain. Study results indicated that differences between the two methods could approach 5% when the cross-section interval was 100 ft. On one of the tested data sets, this difference in construction costs represented $112,500 for fill and $95,800 for cut. Source

Hong S.,University of Wisconsin - Madison | Hong S.,Yonsei University | Vonderohe A.P.,Vonderohe Consulting LLC
Transportation Research Record

The Global Positioning System (GPS) and geographic information systems (GIS) have been integrated for a wide range of transportation applications. When a linear datum is not implemented into the applications, a route measure is indirectly determined with snapped GPS-derived coordinates along roadway centerlines. Thus, uncertainties in output information are subject to various types of error and error sources in GPS and roadway centerline maps and their propagation through spatial operations. A method for uncertainty analysis is presented. The method estimates the quality of output information from GPS- and GIS-integrated applications for transportation. The method involves an analytical GPS error model and an error propagation model, assuming that a test road-way centerline map is representative of roadway centerline maps with the same nominal scale. In the case study, the method was applied to a winter maintenance application and a travel time study. The optimum input data set for each application was determined by sensitivity analysis that explored the impact of positional uncertainties on variations of output information computed from distance-based and non-distance-based computation models. Results indicated that the winter maintenance application required accurate input data because uncertainties in output information were accumulated as winter maintenance vehicles repeatedly treated roadways. However, for the travel time study, consistent output information was computed with a minute level of accuracy, so positional uncertainties in input data had a negligible impact on output information. Source

Vonderohe A.,Vonderohe Consulting LLC | Hollister B.,Methods Development Unit
Transportation Research Record

When designed, horizontal and vertical highway alignment components are parametrically described geometric objects (e.g., smooth curves and straight lines). However, surface models resulting from highway design and for use in construction by automated machine guidance (AMG) are not geometrically smooth. Rather, they are triangulated irregular networks containing straight line segments that serve as edges of contiguous triangular facets. Designers and construction contractors must decide how frequently to discretize parametric design objects for adequate representation by such line segments in surface models. Higher data frequencies, or densities, result in more accurate representations of design. However, high data densities lead to large file sizes, greater storage and data management requirements, and greater data transfer times. This paper presents mathematical derivations that relate minimum required data densities to error tolerances for horizontal and vertical curves. Geometry, physics, and quantifiable human factors are used to couple expressions of tolerable error with parameters of curves and, more fundamentally, with design speeds. An example is provided in which the method was used to produce interim standards for electronic design-AMG for data-sharing pilot projects with the Wisconsin Department of Transportation. The mathematics should be straightforward for incorporation in design software to ensure that individual design objects, groups of objects, or entire corridors are represented to acceptable levels of accuracy, with minimum data requirements, in surface models used for construction by AMG. The scope of this research is limited to control of discrete errors in representations of smooth curves by straight line segments. Uncertainties resulting from measurements are not addressed. Source

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