![]() ![]() Such findings on the relationship between roadway grade and safety, fuel consumption, and network performance indicate that the availability and quality of roadway elevation and grade data will be a critical consideration in the development of a next generation “green” highway design strategy that integrates life cycle maintenance, operation, safety, and environmental cost in the planning stage. Boriboonsomsin and Barth showed that the optimal speed in terms of fuel efficiency changes with grade. Previous work has also identified non-linear relationships between roadway grade and fuel economy. Likewise, degradation of vehicle performance and sight distance at vertical alignments are often causes of recurrent congestion and vehicle collisions. The Highway Capacity Manual (HCM) 2010, for example, assigns values of heavy vehicle to passenger car equivalency factors based on grade changes. Previous research has shown that vehicle performance and fuel efficiency are significantly affected by roadway elevation changes. Roadway elevation data play a critical role in a wide range of transportation analysis and design applications including roadway geometric design, infrastructure construction, safety analysis, fuel consumption estimation, highway capacity analysis, and emergency evacuation planning. Overall, it is found that the high accuracy elevation data available from GE provide a reliable data source for various transportation applications. The methodology validation results indicate that the proposed extraction method can locate the extracting route accurately, recognize multi-layered roadway section, and segment the extracted route by grade automatically. Finally, the proposed extraction method was implemented and validated for the following three scenarios: (1) extracting roadway elevation differentiating by directions, (2) multi-layered roadway recognition in freeway segment and (3) slope segmentation and grade calculation in freeway segment. Mean absolute error (MAE) and root mean squared error (RMSE) are used to assess the accuracy and the test results show MAE, RMSE and standard deviation of GE roadway elevation error are 1.32 meters, 2.27 meters and 2.27 meters, respectively. Geological Survey National Elevation Dataset (USGS NED), which is a widely used data source for extracting roadway elevation. This study also compares the GE elevation data with the elevation raster data from the U.S. ![]() The GE elevation data was compared with the ground truth data from nationwide GPS benchmarks and roadway monuments from six states in the conterminous USA. A comprehensive accuracy assessment of the GE-extracted elevation data is conducted for the area of conterminous USA. This paper intends to address this need by proposing a method to extract roadway elevation data from Google Earth (GE) for transportation applications. However, it has been challenging to obtain such data and most roadway GIS databases do not have them. ![]() Publication manual of the American Psychological Association (7th ed.).Roadway elevation data is critical for a variety of transportation analyses. Retrieved December 4, 2019, from Īmerican Psychological Association. Please see How Do I Cite In-text Two or More Resources by the Same Author That Were Published in the Same Year in APA Style? for information on how to append a lowercase letter after the year of publication to distinguish between resources, and see below for examples: If you're citing from more than one Google map in your text, you will need to distinguish between them in your in-text citations and references. If you're using data from a Google map and quoting or paraphrasing that information in your work, you'll need to cite the data in-text and provide a reference to the source. If you're including a Google map in your thesis or dissertation, please see the information on using maps in Copyright Information For Thesis and Dissertation Publication and give the appropriate attribution in the figure caption. "Because dynamically created maps (e.g., Google Maps) do not have a title, describe the map in square brackets, and include a retrieval date" (American Psychological Association, 2020, p. ![]()
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