Alan P. Vonderohe

Simple map-matching algorithm applied to intelligent winter maintenance vehicle data

Intelligent winter maintenance vehicles are equipped with automatic vehicle location (AVL) technology, including differential Global Positioning System (DGPS) receivers and various additional sensors that collect equipment status and material use data. DGPS data points are associated with the nearest roadway centerline by calculating minimum perpendicular distances between each roadway centerline representation and the DGPS data points. Highly accurate roadway centerline maps and DGPS measurements are not always available. Thus, spatial mismatches may occur at converging and diverging roadways, divided highways, and intersections. Decision makers use winter maintenance performance measures to evaluate achievement of goals and objectives and to improve winter maintenance operations in public agencies. These performance measures are sensitive to spatial mismatches, which need to be resolved before calculations are done. This paper presents a simple map-matching algorithm that resolves spatial ambiguities by determining the correct roadway centerline on which the vehicle is traveling. The algorithm computes shortest paths between snapped DGPS data points using network topology and turn restrictions. A path is considered viable, and locations for the snapped DGPS data points correct, if similarity exists between values of calculated and recorded vehicle speeds. If a path is not feasible, DGPS points are snapped to alternative roadway centerlines contained within their buffers, shortest paths are recalculated, and speeds are again compared. Examples are presented to illustrate the implementation and effectiveness of the algorithm.

Performance Measures for Winter Operations

New winter maintenance vehicles are being equipped with differential Global Positioning System (DGPS) receivers and numerous sensors that collect environmental data (e.g., pavement and air temperature), equipment status data (e.g., plow up, plow down), and material usage data (e.g., salt application rate). These data can be both telemetered to a dispatch center and recorded on magnetic media for later downloading. Data are transmitted and recorded as often as every 2 s. Such data, both type and quantity, have only recently become available. Vehicles were instrumented with the reasonable expectation that information can be used to improve winter maintenance. As a result, these technology demonstration projects tend to be guided by loosely defined “try-and-see” data requirements. Now, with the availability of these data, agencies are beginning to explore the possibilities for improving the performance of winter maintenance operations. A comprehensive set of performance measures for winter maintenance that can be computed from data collected by DGPS receivers and sensors on winter maintenance vehicles is described. The performance measures are indicators of how well winter maintenance operations meet and satisfy expectations. Consideration of the business goals and objectives determined during a series of meetings with state transportation agency professionals from all levels, including winter operations engineers, county commissioners, patrol supervisors, and program managers, led directly to identification of the performance measures. Consequently, the measures directly tie to the business processes and performance of operations. After baseline values of the measures are established, changes in performance can be related to cost of the technology.

Effects of Controlling Parameters on Performance of a Decision-Rule Map-Matching Algorithm

Advanced map-matching algorithms resolve spatial ambiguities between differential global positioning system (DGPS) and roadway centerline data. Most of these algorithms need further research to assess their performances with respect to their controlling parameters and their relationships with spatial data and temporal resolution. This paper presents an analysis of the effects of three parameters controlled by the user and two variables dominated externally through simulated data on the performance of a postprocessing decision-rule map-matching algorithm previously developed by the writers. The algorithm is tested against three different digital roadway map scales from counties in Wisconsin and Iowa, and two automatic vehicle location (AVL)/DGPS technologies mounted on intelligent winter maintenance vehicles. Sensitivity analyses indicate that the algorithm is sensitive to controlling parameter values depending on the data being tested. The algorithm satisfactorily resolves spatial ambiguities given different spatial data qualities, AVL/DGPS technologies, and temporal resolutions. Statistical analysis suggests a direct relationship between data collection frequency and spatial mismatch resolution. Parameter values are presented for minimizing false negatives and maximizing solved cases, thus enhancing the performance of the map-matching algorithm.

Uncertainty and sensitivity assessments of GPS and GIS integrated applications for transportation.

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.

Land records modernization: Centers of excellence from a Wisconsin perspective

Abstract Faculty representing a variety of disciplines at the University of Wisconsin-Madison are planning for the establishment of a center of excellence in land information science, for the purpose of providing a program that develops scholars and professionals, as recommended in a recent report of the National Research Council. They have begun by identifying an interdisciplinary graduate program focused upon education, training, and research required for the development and implementation of large-scale, multipurpose land information systems within the Public Land Survey states. These discussions have identified (a) five reasons to support the concept of centers of excellence in land information studies; (b) five components that are important, if not essential, to the development of a center; and (c) three types of resources at the University of Wisconsin-Madison, including the academic resources of seven departments, institutes, or centers offering instruction in 45 existing courses that are central to or supportive of philosophical and theoretical as well as the technical and application aspects of land records modernization; seven facilities that could provide source materials, research, and technical assistance; and three institutional cooperators. This paper reviews why centers of excellence are needed now, outlines components such a center should include, and discuss current efforts at the University of Wisconsin-Madison that support the center of excellence concept.

Comparison of Earthwork Computation Methods

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-end-area 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 surface-to-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

Planning the Implementation of Three-Dimensional Technologies for Design and Construction: Wisconsin Department of Transportation

112,500 for fill and

Data Density Requirements as Functions of Design Speed: Controlling Accuracy of Representation of Horizontal and Vertical Curves in Surface Models for Automated Machine Guidance

95,800 for cut.

POTENTIAL APPLICATIONS OF GEOGRAPHIC INFORMATION SYSTEMS TO CONSTRUCTION INDUSTRY

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 studys 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.

Enterprise-Wide Data Integration and Analysis for Oversize/Overweight Permitting

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.