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Safe Road Trains for the Environment; developing strategies and technologies to allow vehicle platoons to operate on normal public highways with significant environmental, safety and comfort benefits

Periodic Report Summary - SARTRE (Safe road trains for the environment; developing strategies and technologies to allow vehicle platoons to operate on normal public highways …)

Project context and objectives:

The SARTRE project is exploring the challenges and some of the potential strategies that will enable road trains (i.e. platoons) of mixed vehicle types (e.g. trucks and cars) to operate on public highways (i.e. motorways) without requiring any infrastructure changes and with full interaction with other road users. The lead vehicle of a platoon will have a professionally trained driver who has additional platoon specific training. Following vehicles within the platoon will be autonomously controlled, following instructions received from the lead platoon vehicle.

Through the development of platoon systems and concepts the project aims to demonstrate some core concepts of platooning leading to an eventual step change in transport usage. Benefits are expected to address congestion, environmental and road safety challenges as well as providing added convenience for platoon users who would be able to utilise their time more effectively.

The project is analysing platooning concepts and strategies and also implementing a subset of these in a demonstrator consisting of two trucks and three cars. The demonstrator is targeting use of existing (rather than developing new) sensors and actuators. The demonstration will also include a back office assistant that will allow 'navigate to platoon' to be demonstrated. This function is an aspect of a paid for service where the lead vehicle owners benefit commercially from leading a platoon of vehicles. The service thus needs to ensure 'clients' are able to find and join a platoon when required. The project will include assessments of a business model and specific human factors criteria that may affect the successful adoption of platoons.

Project results:

The project is divided into six Work package (WP)s:

- WP1: Management.
- WP2: Concept Study.
- WP3: Implementation.
- WP4: Validation.
- WP5: Assessment.
- WP6: Dissemination.

WPs 1,6 are ongoing throughout the project with 2-5 being roughly sequential (with some overlap).

The first 18 months of the project has largely been focussed on defining/ understanding the platoon concept and selecting a number of use cases that are being implemented in the demonstrator as part of the implementation WP.

A number of WP2 tasks have been undertaken to ensure a good understanding of platoon issues is achieved:

1. use case definition;
2. traffic modelling;
3. human factors assessment;
4. preliminary safety analysis.

Each of these activities has been used to understand the potential operating parameters and constraints for both a platoon concept and also for the platoon demonstration which is implementing a subset of the identified use cases.

The paper 'Operating Platoons On Public Motorways: An Introduction To The SARTRE Platooning Programme' 2010 by Tom Robinson & Eric Chan (Ricardo UK Ltd) and Eric Coelingh (Volvo Car Corporation) explains some of the complexities in undertaking the programme and some of the conclusions reached.

The use case definition has included the definition of terminology and a set of working assumptions for platoons and also a more detailed analysis of specific use cases, i.e. Create, Join, Maintain, Leave, and Dissolve. In addition back office use cases have been considered, i.e. Register, Handle Platoon Status, Charge Platoon and Guide to Platoon. Use cases have included the main scenarios as well as alternative and exceptional scenarios where appropriate. For example: an exception for Join use case would be the driver of the lead vehicle not accepting a potential following vehicle into the platoon. Some of the conclusions from the use case analysis may be found in the paper 'CHALLENGES OF PLATOONING ON PUBLIC MOTORWAYS' 20010, by Carl Bergenham (SP Technical Research Institute of Sweden) , Qihui Huang, Ahmed Benmimoun (RWTH Aachen University - Institut für Kraftfahrzeuge) and Tom Robinson (Ricardo UK Ltd).

The traffic modelling element of the programme has sought to understand some key parameters relating to the interaction of the platoon with other road users. This task has two elements, one is the modelling of existing traffic behaviour and the second is the modelling of platoons in the context of that behaviour to assess the impact on the platoon and other vehicles. E.g. the time taken to complete a join from side and potential interference to other road users. The analysis has helped in short-listing appropriate platoon strategies that will be implemented in the demonstration system.

The human factors assessment has been undertaken using a simulation environment to assess a number of key issues. The human factor has explored driver and other road user perception of key factors such as distance between vehicles and platoon length. In addition it has been used to assess the level of driver interaction required to ensure safe operation of the platoon. Some of the conclusions from the human factors study may be found in the paper 'SAFE ROAD TRAINS FOR ENVIRONMENT: Human factors' aspects in dual mode transport systems' 2010 by Maider Larburu, Javier Sanchez and Domingo José Rodriguez (Tecnalia-RBTK).

A high level system specification has been defined along with an initial view of the functional architecture. The specification and architecture were used as the basis for the preliminary safety analysis.

The preliminary safety analysis has endeavoured to apply the draft ISO 26262 standard to the platoon concept and proposed functional architecture. It has also considered how future legislation changes may affect risks identified (e.g. considering the platoon as 'one vehicle'). Although not ideally suited to multi-vehicle analysis utilising ISO DS 26262 has allowed some initial safety requirements to be defined for the system. The application of 26262 has also allowed some ambiguities to be identified in the draft standard, in particular relating to operational situations, the definition of hazards, and the relationship between faults and hazards. Feedback has been passed to the ISO 26262 team.

The first project milestone of CONCEPT READY has been achieved and work has commenced on the implementation phase of the programme.

The implementation phase is largely about the development of the demonstration prototype system and involves the modification of a number of vehicles (two trucks and three cars) such that following vehicles may be autonomously controlled by a lead vehicle.

Implementation is progressing well with two cars and one truck being equipped with sufficient sensors and new actuators to allow development of vehicle following control systems. These have been successfully tested by the team with one car following a lead truck at 40 kph. The results have provided valuable information that is being used to develop the system further.

Work has also started on the assessment of fuel consumption, initially using a modelling environment that will explore the aerodynamic characteristics and benefits given selected distances between vehicles. This work will also seek to assess the likely flow and dissipation of exhaust gasses given the selected platooning manoeuvres. An outline of the planned evaluation method has been described in a paper presented at the PRT conference in London in 2010, 'SARTRE: Safe road trains for the environment', 2010, Arturo Davila & Mario Nombelo (Idiada Automotive Technology SA).

Throughout the programme a number of dissemination activities are being undertaken to raise public and stakeholder awareness of the potential of road trains. The programme team has a defined communications strategy that includes the creation of a SARTRE documentary (of which parts 1 and 2 are now available on the web - see: www.sartre-project.eu/en/press/Sidor/default.aspx) and the presentation of papers at conferences.

Potential impact:

SARTRE is a cross cutting programme that aims to address several societal challenges (environment, road safety and congestion) as well as providing added convenience for road-train users.

The following list highlights the anticipated benefits for various stakeholders:

1. Anticipated benefit to society
- reduced emissions;
- reduced road fatalities;
- high capacity usage of roads reduces the number of new roads needed.

2. Anticipated benefits for lead vehicles/drivers
- reduced fuel costs;
- remuneration for leading the platoon;
- added value: sensors can be used for active safety.

Anticipated benefits for following vehicles / drivers
- reduced fuel costs;
- increased convenience through freed up time;
- added value when not in a platoon: sensors can be used for active safety.

3. Anticipated benefits for service provider
- commercial arrangement - being paid for providing the platooning back-office service and the charging mechanism.

4. Anticipated benefits to non-platoon road users
- increased accessibility (assuming that enough vehicles use the platoons);
- reduced congestion;
- more consistent journey times.

The SARTRE programme has an assessment WP that will specifically be looking at these anticipated benefits in order to provide a refined understanding of the actual benefits likely to be achieved. This WP will also look at the platoon roadmap, including an assessment of the non-functional requirements (e.g. legislative) that may be necessary to achieve the desired step-change in transport usage.

The publicity generated by SARTRE has been very successful in raising the profile of ITS (and platooning in particular) as an alternative to building or modifying the road infrastructure: entering 'SARTRE platooning' into Google generates 189 000 results.

List of websites: www.sartre-project.eu