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原文传递 Investigation of Procedures for Maximizing the Accuracy of Photogrammetric Pavement Elevations.

题名：	Investigation of Procedures for Maximizing the Accuracy of Photogrammetric Pavement Elevations.
作者：	Munjy-R.; Hussain-M.
关键词：	Pavements-; Pavement-elevations; *Accurate-surface-data.;Procedures-.
摘要：	Precise pavement surveys are required for the engineering and design of pavement overlays, for pavement widening, addition of high-occupancy lanes, and for median barrier and drainage improvements. A significant portion of the activities of transportation agencies consists of rehabilitation and improvement of existing highways. Accurate surface elevations of existing pavements are often required to locate and correct roadway deformations in both longitudinal and transverse directions, to correct cross fall and drainage faults, and to develop plans, specifications and estimates. The effective use of modern computer-aided highway design programs requires the availability of accurate pavement surface data. The California Department of Transportation (Caltrans) Highway Design Manual requires a 13mm elevation change before a pavement rehabilitation is performed (8,Section 611). The 13 mm elevation change is currently being used in Caltrans as a criteria to identify pavement base failure (rutting) and vertical ridges on the pavement. In order to effectively monitor the change in pavement surface elevation at the 13-mm level, the error in the surface elevation data should not exceed about one-half of this value. It is with this objective in mind that Caltrans Survey Manual specifies that data points located on paved surfaces or engineering works should have a standard error of 10 mm horizontally and 7 mm vertically. Minimum measured distance to meet horizontal requirement is 20m. Maximum measured distance to meet vertical requirement is 150m. Caltrans CAD and DTM programs utilize terrain line interpolation (TLI) string data. TLI data is collected in the field by measuring the elevation of a string of points based on any apparent break points in the profile gradient. This data is also used to generate cross sections. The elevation accuracy requirements of the TLI data at the 7-mm level have traditionally been met by collection of pavement profile data along each edge of the traveled way by using conventional topographic surveying procedures. Historically, millimeter level precision in pavement surface data could only be achieved through differential leveling, a surveying method used for generations. The advent of electronic distance measuring instruments (EDMI) and electronic theodolites has resulted in the adoption of the Total Station Survey System (TSSS) in Caltrans.
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