PPos-Taxi - Efficient Taxi Allocation Based on Precise Vehicle Positioning

The booking office of the taxi company “Taxi 31300” uses GPS positions to automate the allocation of the taxis to the costumers. Due to the currently achieved positioning accuracy of about 10m-15m, it is impossible to identify the driving lane and direction especially in the inner city, on bridges and highways. This may result in waiting times not calcuable for the customer.

The aim of the project is to provide the horizontal position of taxis within a few meters by means of two correction strategies (EGNOS and DGPS) and to test these strategies with regard to accuracy, availability, economic efficiency, and operator convenience. Contrary to similar approaches the correction data will be applied by software in the booking office and therefore do not have to be forwarded directly to the fleet of rovers.

The applied strategies are based on

• using EGNOS-corrections via internet: In urban areas the EGNOS satellites are not visible due to obstructions by buildings, etc., so the raw GPS positions, sent to the central office by the taxis, must be corrected in the booking office in near real-time. Additionally, some taxis will directly try to receive EGNOS- corrections from the geostationary satellites to provide test data for a comparison of the availability and the accuracy reached.
• using correction data of a permanent GPS-station (DGPS): Here the raw GPS position of the taxi is also corrected in the central office, using corrections of the WEP (Wienstrom Echtzeit Positionierung).

Additionally, the independent problem of multipath effects will be reduced by analysis of the signal-noise-ratio of the GPS- signals. The disturbed signal, which has a time delay due to reflections on buildings, trees, etc, can so be identified and removed, and the calculation of the position can be repeated.

After a successful realization of the project "Taxi 31300" has the opportunity to choose the most efficient service before upgrading the 800 vehicles in their fleet. The approach chosen can of course be used in general for fleet management in urban areas.

Coordinator

Institute of Geodesy and Geophysics, Vienna University of Technology - Dr. Michaela Haberler-Weber

Partners

• Funktaxi 31300 VermittlungsgmbH & Co KG - Nikolaus Norman
• Austrosoft ® Weiss Datenverarbeitung Ges.m.b.H. - DI Michael Leitner
• Wienstrom GmbH - DI Christian Klug

Institute of Geodesy and GeophysicsVienna University of Technology
Dr. Michaela Haberler-Weber
Gusshausstrasse 27-29
A-1040 Wien
Tel.: +43 (1) 58801 - 12839
E-mail: Michaela.Haberler-Weber@tuwien.ac.at
Web: http://info.tuwien.ac.at/ingeo/