The same Järva County section of the Tallinn-Tartu highway was the scene of four accidents with in the space of a few hours Sunday. A young woman was killed in one of the crashes, while the Transport Administration had said at the time that it was not satisfied with de-icing precautions on that stretch of road.

Those at the scene said the highway had been particularly slippery at the time of the accidents.

Andres Piibeleht, spokesperson for the Transport Administration said that, nonetheless, drivers should take extra care when traveling in winter, and account for sudden changes in conditions.

"Estonia experiences northern winters, and the road conditions can be very changeable from section to section," Piibeleht said.

"Sunday's tragic accident also happened on a section of road which sees a constant surface wind, which can make road conditions significantly different from the sections of highway either side of it. In such cases, even continuous salting is often not very helpful," Piibeleht went on.

"Living in Estonia as we do, we must take into account that we cannot drive in the winter in the same manner as we do in the summer," Piibeleht continued.

"We get all four seasons, and in winter we have to bear in mind that the roads will be slippery - whether we want them to be or not. If it is snowing, it means the temperature is below zero and there is a wind – that renders it possible to guarantee summer driving conditions on all roads," Piibeleht added.

"When the temperature fluctuates, the road can become slippery even when there has been no heavy precipitation - but ice rain can transform large swathes of Estonia into a virtual skating rink in just a few minutes, while all heavy precipitation brings with it snowy roads. This is all by the way in spite of the fact that road maintenance vehicles are all out at work at full capacity."

Analysis of Sunday's accidents revealed that road maintenance personnel assessed the situation at 8.37 a.m., at the Paia intersection, roughly halfway between Tallinn and Tartu, and, while surface blizzard conditions were found, the grip factor as measured was acceptable (at 0.36, where a minimum of 0.3 is required).

This remained the case for three hours, until the first notification of particularly slippery road surfaces came in at 11.43 a.m., when the Police and Board Guard Board (PPA) were informed of an accident.

Since there had been no knowledge of these exceptionally slippery conditions beforehand, and no reason to proactively predict them, precautions such as a grit spreader had not been deployed.

"The measurement results indicate that the road surface met the established requirements prior to the accident(s)," Piibeleht said.

Piibeleht added that when driving, be it the 15 minute commute to work, or a several-hours' drive to the other end of Estonia, more time must simply be factored into journeys, during winter time.

Speeds should be selected according to the conditions, while the maximum speed limit is just that, an upper cap and not a mandatory speed to be maintained at at all costs, Piibeleht added.

The Transport Board says on its website, in English, that there two highest condition levels in Estonia, referring to the busiest roads, divide: "Into two - level '3+"'and level '3'. There are 1,638 km of level '3+' roads and 1,649 km of level '3' roads. These are the major national roads: Tallinn to Narva, Tallinn–Tartu–Võru–Luhamaa, Tallinn–Pärnu–Ikla, their support roads and a few secondary roads that have more traffic."

"Snow control is conducted within five hours after a snowfall or blizzard has ended, at the latest. The thickness of critical, fluffy snow must not exceed 4 cm, while the thickness of critical wet snow [must not exceed}] 2 cm."

"De-icing is conducted at the level '3+' within 2 hours and at the level '3' within four hours after slipperiness has occurred, at the latest," the board adds.

Piibeleht called Estonia's road maintenance requriements "relatively similar to those of neighboring countries," including Finland.

In Estonia's northern neighbor, requirements for ensuring road grip facto depend on the distribution of the roads (there are six categories), while maintainers have between zero and seven hours to react. 

Roads in Latvia, comparable with Estonia in size, are divided into five categories, with the requirement to eliminate slipperiness within three-to-six hours, while there are no standards on certain roads.

The board currently has no plans to tighten the requirements in force in Estonia Piibeleht added, noting that upgrading one level in each case of road category doubles maintenance costs.

The Transport Board and its public and private sector partners carry out winter road maintenance on more than 16,600km of national roads, of which almost 4,000km are roads with the higher condition levels (see above).

The board has 387 units of equipment to use for road maintenance - 214 base trucks, 39 gritters and 134 tractors

Anti Palmi, head of the Transport Administration's infrastructure and maintenance department, told ERR Monday that anti-slippage activity had been insufficient to the task, adding that while the board endeavors to prevent slippage in accordance with all requirements, road and weather conditions are changeable and it is not always possible to do so at the rate road users might expect.

AS Tariston has the contract for road maintenance in Järva County. Alvar Aedma, head of road maintenance at Tariston, says the cause of the slippery conditions which led to the accidents Sunday was a surface blizzard.

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