In Finland, passenger cars and vans must have studded or studless winter tires from the beginning of December to the end of February. There are still no reguirements for the grip capabilities of tires in winter conditions. In winter tyre tests, it has been demonstrated, that the grip of Middle European studless tires in icy conditions is much lower than Nordic studless tires. The object of this study is to examine, would it be worthwile to lay an ice grip approval demand for studless tires in Finland.
Four scenariour were analyzed in the study: A) present state (present winter tyre type distribution) and no ice grip approval, B) present state with compulsive ice grip approval, C) the share of studless tyre increase and no ice grip approval and D) the share of studless tyre increase with ice grip approval (table 1).
Table 1. The scenarious in the study. *=possible winter tire type distribution in Finland, if Helsinki will exceed the target of 75 % studless tire share in 2030 as planned.
The accident risk of different winter tyre types in different conditions were concluded in the basis of litterature and calculations. Because the available detailed information is quite limited, the risks were partly assessed (table 2).
Table 2. The relative accident risk of different winter tyre types in different conditions. The calculation is based on the assumption, that risk of studded tires is 1.
According to calculations made with accident costs, the compulsive ice grip approval will give 0,9 million euro savings in present state. If the share of studless tires will increase like in scenario C, the ice grip approval will give 2,7 milloin (26,2-23,5=2,7) yearly savings (table 3).
Table 3. Number of accidents and accident costs in relation to the present state (scenario A).
It was assessed, that if the compulsive ice grip approval will be brought into force, there will be development, passing and testing costs about a half million euro before the approval is coming into force. If the approval will happen in present state, these cost will be spared during first year with approval (scenario B). The starting costs will be spared in few months, if the approval will come into force in situation, when the share of studless tires is bigger (scenario D). The costs have been assessed in table 4.
Table 4. The costs before ice grip approval comes into force, and costs after approval has come into force.
The ice grip approval will not have direct effects on the ground, water, air, climat, vegetation, organisms, their mutual interaction and nature diverseness, living conditions and comfort, people health, urban structure, buildings, landscape, cityscape and cultural heritage nor the utilization of natural resources. However, when the number of accidents will decrease, the negative effects of traffic on the environment and people will be reduced. Ice grip approval will increase the testing and promote the development of Lapland. If approval would expand to the Sweden and Norway, it will promote Nordic traffic safety, will make formalities on the borders more easy and will bring broader markets for tyre manufacturers.
The report (in Finnish) can be found here.