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Motorway winter service: out and about in a snow plow

Dino Eisele
Motorway winter service
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The snow was in the air. But he wouldn't stay there, that was the problem. You could feel it, some say, your bones ached or itched. Peter Szautner knew that the snow would come, and he also knew when: at night.
D he man doesn't rely on his bones, he trusts SWIS. The road weather information system provides the chief of operations with a colorful image on a screen at the Kirchheim /Teck motorway maintenance facility. Blue means: risk of slipperiness. Red: smoothness. Violet: 'End of the world', says Szautner.

400 kilometers of blowing snow

The shift change at seven. It's cold, dark, nobody speaks much. They drove about 400 kilometers in the night, the dance of thousands of flakes glaringly illuminated in front of them, the plow scratching on the asphalt, and the orange flashes of the warning light from the cabin roof, maximum speed 60. 'Six times Kirchheim – Stuttgart and back, none Pause, and that stupid snow, it was right back behind the plow, vicious snow. '

Bernd Nething's eyes tell the story of last night before he prepares the truck for his colleague on the day shift. Ten times he pushes the shovel of the wheel loader into the white mountain in the hall next door, ten times he dumps it over the rear of the clearing vehicle. Ten tons of salt plus almost 3,500 liters of brine in tanks to moisten the salt before the spreader disc at the rear throws it onto the road. Five to 40 grams per square meter. On average, around 15 are enough because a thermal camera measures the road temperature and the driver can set a spreading program depending on the road conditions.

When Robert Wendling and three colleagues get onto the A8 at half past seven, the display shows a street temperature of minus 3.5 degrees. With a personal number, he logged into a GPS that records when and where he is spreading how much with the clearing vehicle, how fast he is traveling and whether the almost four-meter-wide front plow and the 2.7-meter-wide side plow are pushing over the road or Not. 'Then let's go,' says Wendling and presses against a small joystick.

Everyone's brain freezes

It lifts the 33-ton truck out of bed when the almost two-ton front plow hits the asphalt and spits a gray-brown slush fountain to the right. 'In winter,' says WendlingLook in the rearview mirror, 'everyone's brains freeze.' What he means by that is demonstrated by a car that passes by on the left, Wendling's colleagues almost hang in the spreading plate, pulls them over and pushes their way between the spreading vehicles. It will go on like this with regularity. 'Everyone wants clean roads. But nobody wants to wait. And a few kilometers further they are stuck in the guardrail.'

Under the front plow, orange sparks jump over the asphalt, the rush hour traffic intensifies, and the three gritting vehicles follows a line of lights. Wendling tells the story of a BMW. The driver had tried to overtake the gritting vehicles at the last minute on the right. 'They later picked the lumps of mud, salt and broken glass out of his throat. The stuff had broken through the windshield and flew through the interior to the rear window.'

More than 40 accidents around Stuttgart

Can Wendling suffer from the snow? 'Yes,' he says and smiles. The first ton of salt is outside at Stuttgart Airport. Your smell mixes with the air and your lips taste like after a day at the sea. The icicles grow on the mirrors, at 40 km /h the diesel sings softly to itself. Madonna not. 'Holiday', she crows from the radio, 'it would be so nice.' More than 40 accidents around Stuttgart, snow all over the country, 'drive carefully,' pleaded a moderator. On the right, a dark A3 pushes past on the hard shoulder.

Every day around 140,000 vehicles drive on the A8 between the Stuttgart junction and the Mühlhausen junction, which the Kirchheim /Teck motorway maintenance authority has to take care of, with branch lines almost 96 kilometers. In operation since 1937, it is the oldest of the roughly 160 German motorway maintenance depots. The first main road foreman Peter Szautner calls it 'A-Emmen' and the motorway next to his office is a 'main artery'. In the winter of three years ago, Szautner's people spent 3,800 hours in the clearing vehicles, drove 100,000 kilometers, scattered 7,600 tons of salt and added more than 400,000 liters of brine.

Outside, it continues to trickle quietly. 'It's still fine this morning,' says Robert Wendlinger, while the spreader has just squandered the third ton of salt. Back at the motorway maintenance depot, it will be exactly 4,261 kilograms. Four shovels of the wheel loader full before Wendlinger sets off again. Junction points, shoulder tracks. The plow shovel pushes past the cat's eye and emergency telephones with centimeter precision.

'At some point you get a feeling,' he says. 'You know your car, you know the route, the snow.' And the info system knows when and where it comes down: nationwide in the next few hours. Peter Szautner sees a lot of blue and red when he checks the screen. If his people weren'tIn continuous use since the previous evening, a different color would come: purple. The end of the world. On the streets at least.

Why does salt thaw ice and snow?

Water freezes at zero degrees. The otherwise loosely dancing molecules combine to form a solid crystal lattice. Its surface is covered by a thin film of water. The water splits salt - sodium chloride - into positively charged sodium and negatively charged chloride ions, and the water molecules in turn bind to them. The salt disrupts the crystal lattice formation by removing water molecules - negatively charged oxygen, positively charged hydrogen - from the lattice and binding them in the salt water that is created. Its freezing point is around 21 degrees below zero. On the one hand, this means that the streets won't freeze over again anytime soon. On the other hand, if the thermometer drops to 21 degrees Celsius, road salt will no longer do anything. At a temperature of minus ten degrees it takes 157 grams of salt to melt 1,000 grams of ice. At minus 15 degrees, 235 grams of salt have to be used to thaw the kilo of ice.

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