Study of infrastructure support and classification for automated driving on Finnish motorways

Finnish Transport Infrastructure Agency set a project to assess the feasibility of Finnish motorway section between Helsinki and Tampere on E12 highway for operation of SAE Level 3-4 automated vehicles, to propose a framework for service level classification for them and to prepare a proposal for further actions in this field.

Feasibility of motorway for automated vehicles

The feasibility of the current road network for automated vehicles was assessed with a detailed inventory of the selected motorway section on E12 highway between Helsinki and Tampere, the overall length of 160 km per direction. Overall, the assessment proved that the current physical and digital infrastructures provide good support for the basic use cases of SAE Level 3-4 driving automation. The project team did not identify any major defects that would require immediate corrective actions with regards to supporting automated driving on motorways.

Service level classification

The service level classification was built on the ISAD (Infrastructure Support for Automated Driving) levels but was extended to other relevant attribute areas, namely physical infrastructure, environmental conditions, and dynamic elements. The five ISAD levels from E to A remained:

E: Conventional (physical) infrastructure only, no AV support

D: Static digital information / map support

C: Dynamic digital information

B: Cooperative perception

A: Cooperative driving

The new attribute areas were labeled following the original logic in digital infrastructure.

The level thresholds were partly quantitative, where applicable data exists, and partly qualitatively described. The likely ODD attributes were compiled based on existing literature, and the validation and reformulation of the attributes based on the implemented field measurements and the views of corresponding experts. The ODD attribute list was compressed to the most critical attributes, that are applicable in motorway environment and that can be provided with threshold values between the service levels, based on the current knowledge.

The accomplished work should give the national authorities and operators a solid understanding of the most critical parts of the infrastructure regarding conditionally or highly automated driving. The classification framework was set for motorways. Anyhow, it was assessed that the proposed ISAD classification does not require many changes in terms of classification attributes to be applicable for also other main roads. The created framework should work well in the communication of the overall and thematic AV support for the users and developers.

The classification was made for motorways in the Finnish conditions only. It must be noted that the level A of proposed classifications is not regarded as a vision to be realised within the next decades on the Finnish road network. According to the E12 case study, the Finnish motorways are likely corresponding quite nicely to the proposed classification, with most sections reaching level D and many even level C.

Further actions

There are many topics that require active follow-up of international standardization of AV support and related technological development.

More analysis is seen to be needed to assess the cost for upgrading specific attributes on, e.g. motorway networks from the current level to the next, as well as, critically, the obtained socio-economic benefit. As the penetration of conditional and highly automated vehicles may be slow, focus should be at first on the so-called “no-regret” actions, benefiting both manual and automated driving, that have been identified in the cost-benefit analyses.

With regard to facilitating automated driving, an important future target is to develop, deploy, operate, and maintain a secure, up-to-date, standardised data set containing the values of each ODD attribute utilised in the ISAD classification. This should cover all road networks where highly automated driving of SAE Levels 3–5 is to be permitted.

Further information

For more information, please see project report:
FTIA (2021). Automated driving on motorways – Study of infrastructure support and classification for automated driving on Finnish motorways. FTIA publications, 21/2021, Finnish Transport Infrastructure Agency.

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