Road charging needs trust and assistance

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10 March 2010

As Europe’s roads become more congested, governments are looking for ways to better manage traffic and pay for the upkeep and development of the network’s infrastructure. Increasingly, satellite navigation applications for congestion management and fair and flexible road pricing are being seen as a means of achieving those ends.

The use of automated road pricing systems can ensure that revenues are based on actual road usage, creating a financial incentive to change driving behaviour. It has the potential to reduce congestion, lower vehicle emissions and generate revenue streams for infrastructure improvement. It can also be designed to encourage commuters to use more public transport.

The principal objective of the SIGNATURE (SImple GNSS Assisted & TrUsted REceiver) project is to prototype a solution based on satellite navigation technologies. Satellite navigation services based on Europe’s EGNOS can provide a flexible road user charging system that can deliver a high integrity, or trustworthy, solution in a cost-effective and scalable manner.

In particular, the project aims to use EGNOS to reduce the time to first fix and the positioning integrity, greatly enhancing the reliability of GNSS based systems. The 18-month project is co-funded by the European Commission through the Seventh Framework Programme for Research (FP7) and started work in February 2009. 

“For road charging applications very high integrity with high availability is required,” says Kevin Sheridan of the project’s coordinator Nottingham Scientific Limited (NSL). “99.9% or greater reliability of data is needed to reduce problems with billing vehicle owners and to boost the confidence of users that they won’t be charged for trips they do not make.”

Pay as you drive 

Road charging schemes to date have focused on specific road segments, such as urban centres, particular infrastructure projects, such as bridges and toll motorways, or classes of vehicle using fixed roadside infrastructure.

This type of fixed technology is not a feasible option for more extensive charging schemes that will need to cover far greater areas, such as an entire country, more road types and practically all private vehicles.

In addition, there will be demand for a fully flexible system with variable charges that depend on the location of the vehicle and the time of day. These flexible schemes will require the positioning element to be on-board the vehicle.

Satellite navigation-based positioning technologies have been identified as the best option to achieve this. The challenge is to develop and demonstrate solutions that can reliably determine a vehicle’s position even in the most demanding operating environments, such as in an urban environment where buildings might block satellite navigation signals.

“The goal for road applications is to have a simple ‘pay-as-you-go’ box,” says Sheridan. “This will integrate into one system for navigation, road charging, emergency response and other applications. The key is to provide a value-added solution. Car makers – and users – will want just one box in the vehicle not 20. And the unit will need to be able to display information on route charges and provide route guidance and traffic travel information.”

EGNOS assistance

The project aims to demonstrate a robust positioning system based on low-cost global navigation satellite system (GNSS) components that work reliably – even in demanding urban environments.

This achievement will be critical to supporting its adoption as the core technology for applications such as congestion management, fair and flexible road pricing, and pay-as-you-drive insurance applications.

The first critical step to this high-availability, high-integrity solution is the delivery of reliable location information via the EGNOS Data Access System (EDAS). The EDAS service allows users to 'plug in' to EGNOS by providing access to satellite navigation data generated by ground stations distributed over Europe and North Africa.

EDAS will allow a vehicle’s on-board unit (OBU) to quickly acquire the GPS signal and accurately position a vehicle during any journey. The OBU platform is being developed by project partner Istituto Superiore Mario Boella, a private research centre based in Italy.

“The time to first fix is very important for accurate road billing,” explains Sheridan. “The aim is to minimise the delay in accessing high quality positioning data when the vehicle starts moving.  Assistance data will come from EDAS, which provides convenient access to all the necessary inputs.”

The OBU can be either fitted with a commercial GPS receiver or an experimental reconfigurable receiver that is being developed for the project by the Ecole Polytechnique Federale de Lausanne in Switzerland.

“The experimental receiver is designed to be highly sensitive and to detect the low strength sat-nav signals that are typical of driving in the urban environment,” Sheridan explains.

Positioning algorithms

The second key factor in achieving the necessary integrity of the system is the implementation of embedded GNSS reliability algorithms in the OBU to provide an assurance of the positioning information.

The new positioning algorithms have been developed by NSL, which specialises in GNSS applications and technology. Only when a system is aware that there is an error can it take action to correct it in real time.

“The NSL software is designed for the specific job of increasing the integrity of the data,” says Sheridan. “NSL has done similar work for aviation and other position-critical fields. By integrity of a system we mean the ability of a system to identify when it is not working properly.”

During a journey the assured positioning data is accumulated in the unit and is transferred to NSL’s Service Centre when the journey is completed. In the Service Centre the position data is assessed by processing it with a map matching application, called a Map-Matcher, which relates the route data to road segments and relevant charging rates to produce a bill for the vehicle’s owner.

Galileo Application Days in Brussels

During Galileo Application Days, SIGNATURE will be showing flash animations of the system at work at the event’s Application Village. “We have produced a live video of a car equipped with a road user charging OBU that will give visitors a real flavour of the whole process,” says Sheridan.

A vehicle’s route and speed will be displayed and the demonstration will show how data collected on this trial journey is sent back to the Service Centre and processed by the Map-Matcher to assess billing accuracy, integrity and availability. A car with SIGNATURE equipment on board will also be on the stand.

Galileo Application Days, 3-5 March, kicks off this year’s European Satellite Navigation Competition (ESNC). Live demonstrations of cutting-edge satellite navigation applications using EGNOS and Galileo will be held at the event’s ‘Application Village’.

The event is being organised by the European GNSS Supervisory Authority (GSA) and the Application Centre for Satellite Navigation in Oberpfaffenhofen (AZO), the managing organisation for Galileo Masters.

The European Geostationary Navigation Overlay Service (EGNOS), Europe’s first venture into satellite navigation, improves the open public service offered by the USA’s Global Positioning System (GPS). Known as a satellite-based augmentation system (SBAS), EGNOS provides both correction and integrity information about the GPS system, delivering opportunities for Europeans to use the more accurate positioning data for improving existing services or developing a wide range of new applications.

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More information:

Galileo Application Days

Updated: Sep 01, 2014