A FAST GPS-BASED SYSTEM FOR SURVEY CHECK OF ROAD ALIGNMENTS

摘要

Survey check of road alignments is an important quality assurance procedure in road construction. Before the kerb lines are actually laid, engineering surveyors have to set out road alignment reference marks and indicators. The positions of these indicators would be checked independently by consultant surveyors to ensure that they are set out according to design parameters. Many surveying methods can be adopted to set out and carry out survey check of road alignments. The most commonly used appreach is by radiation with a total station [see e.g. Uren J. and Price W.F., (1978), Schofield W. (1993)]. This conventional surveying method has the disadvantage of requiring a sufficient number of intervisible control points near the survey area. To fulfill this requirement, sufficient control points have to be maintained inside the project area throughout the project period, which is a difficult task for surveyors in complicated construction site environments. When consultant surveyors carry out the survey check of road alignments with the conventional method, they always encounter the same difficulty that request for survey check of setting out work is in a rather short notice, the results of which have to be reported as quickly as possible in order not to delay the progress, however, time is required to re-establish control points and to carry out data processing of survey check results. In order to alleviate this pressure imposed on consultant surveyors, a fast GPS-based system for survey check of road alignments is proposed. This system combines the GPS positioning techniques with an automatic database search and computational algorithm. With the high precision GPS Real-Time Kinematic (RTK) [ see e.g. Hefmann W. (1992), Leick, A. (1995) and Mi.sra P. et al. (2001)] positioning results fit into the processing engine, survey check results can be reported on-site.