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KEY WORDS: Car Navigation, Map Matching, GPS-Masking Effects, GPS-second way effects, Integrated Traffic Management 
ABSTRACT 
Modem car navigation systems are based on odometers, heading sensors (differential odometers, gyros, magnetic field sensors) and GPS 
or DGPS facilities. 
85% of mobility activities in road traffic occur in urban areas. The availability of GPS is heavily restricted due to masking and second 
way effects. Therefore a combination of different positioning sensors is required to overcome the GPS-availability problem. 
Especially the GPS-positioning of railways in urban areas and in terminal situations requires a compensation of the missing GPS-signals 
also for train positioning for radio-based railway guidance systems. 
KURZFASSUNG 
Moderne Fahrzeugnavigationssysteme nutzen Multisensorsysteme (Differentialodometer, Kreisel, Magnetfeldsonden) in Kombination 
mit GPS/DGPS. 
85% aller Fahrten mit dem PKW erfolgen in städtischen Ballungsräumen. Die Verfügbarkeit von GPS durch Abschattung und 
Reflexionen beeinträchtigen die Verfügbarkeiten erheblich. Daher wurden Multi-Sensor-Modelle benötigt, um diese GPS- 
Verfügbarkeitsprobleme zu überwinden. Insbesondere für die Ortung im Schienenverkehr wurden aus der PKW-Navigation bekannte 
Zielführungssysteme auf der Basis von Map Matching-Technologien zukünftig eine wachsende Rolle spielen. 
1 MAP MATCHING PROCESS 
Up-to-date car navigation systems with integrated map matching 
are under research in the study. Setting-up sensor models for 
magnetic field sensors, differential odometers combined with 
GPs, differential odometers combined with DGPS, gyros, 
odometers, and GPS or DGPS were analysed in terms of the map 
matching procedure. It can be shown that odometers together with 
heading sensors lead to a curvature of vehicle trajectory of the 
road or rail. This curvature can also be extracted from the traffic 
network data base (Digital Road Map, Digital Rail Map). In 
combination with GPS or DGPS typical sensor characteristics are 
modeled in a multi-sensor approach. Different map matching 
techniques were developed for map matching processes for 
curvature pattern, angular pattern and trajectories in cartesian 
coordinates. During the map matching process in the coordinate 
pattern line elements of the driven road way and elements of the 
digital map are compared. A theoretical background for multi 
sensor map matching processes and the achievable positioning 
accuracy relatively to the road network for emergency systems 
were approved in practical tests together with Daimler-Benz. 
INTEGRATED TRAFFIC MANAGEMENT 
traffic management systems 
A new market of information providers will be developed. Traffic 
information has to be captured, integrated, and processed for 
user-specific interfaces via appropriate communication channels 
as satellite communication, mobile telephone networks and 
terrestrial communication networks Basic requirements for 
information of traffic participants can be described by 
- what happened, 
- when 
- where 
- on the traffic network? 
Future clients are provided by pre-trip information at home or by 
up-to-date traffic information inside the vehicle or train. 
Individual traffic guidance systems provide the connection of 
driver information systems to the infrastructure. Basic examples 
are shown in the German pilot project LISP. Necessary 
information density for successfiil operating of these systems will 
be extremely high. Provision of complex broken information 
chain in parallel to the traffic guidance process are mainly 
unexplored. Especially for safe operational guidance techniques a 
new quality standard has to be developed than available today in 
geodetic information theory. This is a challenge for industrial and