International cooperation and technology transfer

Fras, Mojca Kosmatin

Bibliographic data

Monograph

Persistent identifier:: 856490555

Author:: Fras, Mojca Kosmatin

Title:: International cooperation and technology transfer

Sub title:: Ljubljana, Slovenia, February 2 - 5, 2000 : proceedings of the workshop

Scope:: VI, 163 Seiten

Year of publication:: 2000

Place of publication:: London

Publisher of the original:: RICS Books

Identifier (digital):: 856490555

Illustration:: Illustrationen, Diagramme

Language:: English

Usage licence:: Attribution 4.0 International (CC BY 4.0)

Publisher of the digital copy:: Technische Informationsbibliothek Hannover

Place of publication of the digital copy:: Hannover

Year of publication of the original:: 2016

Document type:: Monograph

Collection:: Earth sciences

Chapter

Title:: HIGHWAY SURVEYING WITH DGPS BASED ON RTCM SATELLITE CORRECTIONS. S. COSSI, M. MARSELLA, C. NARDINOCCHI, L. TOMBOLINI

Document type:: Monograph

Structure type:: Chapter

HIGHWAY SURVEYING WITH DGPS BASED ON RTCM SATELLITE CORRECTIONS S. COSSI, M. MARSELLA, C. NARDINOCCHI *, L. TOMBOLINI ** D.I.T.S - Facolta’ di Ingegneria - Università’, di Roma "La Sapienza * D.I.C. Facolta’ di Ingegneria -Università’ di Parma ** Trimble Italia Commission VI Working Group 3 - Commission IV Working Group 3 KEYWORDS: highway surveying system, kinematic GPS, odometer, differential RTCM GPS, quality assessment. ABSTRACT A number of tests involving GPS receivers in various kinematics settings were conducted to assess the performance of GPS used in support of highway surveys. The main objective was to experiment the recently developed GPS Pro XR/XRS Trimble receiver for determining trajectories and reference point positions of a land vehicle dedicated to road maintenance. The performance of this single frequency receiver, equipped with internal antenna for receiving satellite transmitted RTCM correction, was evaluated by using, as reference, precisely determined positions. Different surveys were performed both in continuos kinematic and in Stop and Go mode. In order to define an accuracy range for RTCM corrected positions, the tests were conducted mounting the Pro XR/XRS system on a vehicle of the Societa’ Autostrade equipped with an odometer and a geodetic dual frequency GPS receiver. Chainage values, conventionally adopted for localising objects during road surveys, are extracted from the GPS co-ordinates and compared with those derived by the odometer. Preliminary results from the tests are presented and discussed. 1. INTRODUCTION The present work examines the use of GPS for the kinematic positioning of a land vehicle dedicated to road survey; in particular, focus was placed on the necessity of the highways survey, where different vehicles are used to measure parameters about road surface characteristics. On the basis of these parameters, the related maintenance activity can be planned; therefore it is necessary that the employed vehicles are able to assign a spatial position to every data samples, which should correspond to a unique point on the road. The spatial position is usually assigned by means of a one-dimensional cumulative co-ordinate, know as mile chainage. The origin of the co-ordinate is set on conventional points, which can be different for each path of highway. In most cases the vehicle dedicated to road survey are able to measure the mile chainage through an odometer. Where possible, a number of reference points are established in correspondence of a stable and well visible object (as road signs or junctions). In a typical highway survey the vehicle proceeds at a constant speed (about 70 km/h) on the right lane of the road, as close as possible to the border line; when passing by the reference points the operator bits an impulse which is recorded by the on board computer. Additional points in support of a better localisation of the measured technical parameters can be determined on the way; the position of these points is computed relatively to the main reference points. The most advanced systems include also a video camera on board of the vehicle, which acquires images to help in the positioning processing. The described measurement system has the following characteristics: 1. the mile chainage is a relative measure without geographic meaning; therefore the collected data cannot be either overlapped to data from other source or referred to a cartographic reference system; 2. the accuracy of the vehicle’s positions is in the range of 50 to 100 meter every kilometre (the lower errors can be obtained when the route is quite regular); 3. the durability of the reference point is not guarantied. With the aim to define an alternative procedure for positioning data collected on the road, a number of field experiments were carried out in this work. Initially, the performance a recently developed GPS receivers (Trimble Pro XR/XRS) was investigated in different environments. Secondarily different tests were executed on highways where a vehicle equipped with an odometer was adopted. Finally, a hardware solution is proposed to be adopted for operational survey. 2. THE USE OF GPS IN THE ROAD SECTOR Recently developed models of GPS receivers (single frequency only code) results particularly suitable for accurate and reliable kinematic survey. In these new receivers the signal acquisition system is very robust against the noise that is very frequent in a typical dynamic environment. Moreover the achievable accuracy (about 1 -2 meter), is quite satisfactory for most of the applications in the road sector. Among these new types of receivers, the Pro XR/XRS Trimble system was selected to carry out the experiment described in the following. This receiver uses twelve channel for tracking Ll/CA code with carrier phase filtered observations. It is an integrated GPS/Beacon/Satellite Differential receiver with Everest™ multipath rejection technology. The given accuracy (RMS) for differential correction is of 50 cm plus 1 ppm for horizontal components and submeter plus 2 ppm for the vertical

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