Overview of ITIS probe data technologies

Floating Vehicle Data (FVD^®) is ITIS’ patented technology for generating high quality real-time and historic road traffic information. The FVD^® core system has been developed, to generate travel times across oriented links of the road network by using the available probe data at the deployment site, be they GPS boxes or Cellular handsets. As such FVD^® source data can be divided into two categories depending on the raw location information used to generate traffic information:

· GFVD: GPS-FVD is based on anonymous tracking of fleets fitted with GPS devices.

· CFVD: Cellular-FVD, which is dependant on anonymous location attributes from cellular handset movement in a cellular network.

In most cases the use of either data source (GFVD or CFVD) in a deployment site is sufficient to generate reliable traffic data in isolation; however data from both GPS and cellular sources may be merged in the same core FVD^® system along with existing traditional roadside traffic infrastructure, such as cameras, loops and sensors. A hybrid sourced FVD^® system can lead to an enrichment of the traffic information gathered and extend the coverage of the system.

The advantages of ITIS probe data technology can be summarized as follows:

Advanced GIS modelling. Advanced GIS techniques are used to model the topology of the road network taking account of the different turning options within a given network. This means the system can provide accurate traffic information in complex road networks such as dense urban areas.

Data independent. The technology is not dependent on any single positioning technology and can be adapted to take almost any form of location information. The algorithms have been developed to cope with inaccurate locations and very noisy data to achieve the accuracy and comprehensive road coverage required to provide high quality traffic information.

Travel time, not velocity. The technology is based on extracting travel time information and not velocities from the supplied data. This has the advantage of providing extremely accurate journey time information.

Merging of historic and real-time data. The system does not consider traffic information to be static but combines both historic and real-time traffic information to generate accurate predictions of traffic congestion.

To identify the different source data, ITIS uses the term “GFVD” for GPS based Floating Vehicle Data and “CFVD” for Cellular based Floating Vehicle Data.

CFVD™ technology

By sampling the location of a mobile phone over a period of time, the route and velocity at which the phone is travelling can be determined. While an individual record of a mobile phone’s position is typically less accurate than that of a corresponding GPS record, this is compensated for by the large number of mobile phones on any road, knowledge of the underlying road network and the application of statistical techniques.

The ability to position a mobile phone within a cellular network is well understood. However, to create highly accurate traffic information there is a number of challenges to be overcome. These include collecting data without compromising an individual user’s privacy, de-cluttering the millions of data points available into a usable data stream and map-matching the resulting patterns to the road network so as to measure velocity and travel time. Drawing on experience from defence and military intelligence, ITIS has used advanced statistical techniques to solve these issues and to generate an economically viable source of traffic information.

CFVD^TM System architecture

The method of collecting the data from the cellular operator is totally passive - it does not add any load to the cellular operators system as it does not require any additional signalling to the handset. The data required by the core FVD system is already on the operator’s network. The data transferred to the ITIS application does not identify individual handsets or users as it is made anonymous prior to transmission.

Location event records that are being produced over the cellular network are monitored by a probe installed on the links between the network elements or directly off the cellular hardware, the switch, depending on the configuration of the mobile network. These location events are monitored anonymously by the ITIS CFVD™ system to derive the movement path and speed of the mobile devices when overlaid on a digital map (GIS). The CFVD™ software can also receive data from other location devices such as GPS enabled cellular phones or vehicles equipped with telematics devices.