Even notorious speeders brake for them: 65 years ago, on January 21, 1957, the first stationary speed trap in Germany went into operation.
Today, mobile systems and hand-held measuring devices do most of the work.
But there is still a prominent, stationary facility in the district, overseen by the Holzkirchen motorway police.
Some days it clicks there 400 times.
Holzkirchen
– The four young Arabs knew that they would be photographed. In August 2016, they smirked and presented the victory sign as they raced north at 193 km/h in their rented Opel Astra under the Irschenberg motorway gantry. They thought about their imminent departure and apparently felt like turning their noses at the highway police. However, they had not expected Police Chief Inspector Thomas Wagner (58).
Wagner is an old hand.
Since 1990 he has worked for the Holzkirchner motorway police and is responsible for technical traffic monitoring.
His flagship is on the Irschenberg: the sign bridge there, equipped with digital measuring technology since 2014, never takes a break.
"It runs 24 hours a day," says Wagner.
However, the recordings are not transmitted online.
"I drive there twice a week and load the data onto my laptop," says the 58-year-old.
In the office he checks the catch.
200 to 400 images can be generated daily.
It is usual for Wagner to burn the photos onto a DVD and send them to the traffic police in Rosenheim.
The police administration office in Straubing then collects the fines.
The speed offenders were asked to pay at the airport: 1263.50 euros
On that August day in 2016, the rather sharp image of the four smirking Arabs suddenly popped up on Wagner's laptop.
"It was clear that things had to be done quickly." A phone call to the colleagues from the airport police - and the driver was promptly caught.
The treasury was happy about 1263.50 euros.
The obvious willfulness had doubled the fine.
The measuring system on the Irschenberg is linked to pressure sensors in the roadway.
The system records the speed, deducts limit values and only triggers a recording if the current maximum speed is exceeded.
"Most of the time we drive there at 100 km/h," says Wagner, "it goes downhill, then there is a right-hand bend - an accident black spot."
Before 2014, Wagner still had the choice of which of the four gantries of the Holzkirchner section he would equip with the analogue measuring system.
"These were wet films, after 420 frames it was over." In the end, when the film quality was poor and the number of development laboratories became fewer and fewer, the image quality suffered.
The old technology has been completely phased out.
And Wagner no longer has to make a decision: the new system is only installed on the Irschenberg.
"Section Control" is the name of the technology of the future
The technology of the future is called "Section Control": The speed is not recorded at one point, but the average speed between two measuring points is calculated.
"We don't have that yet," says Wagner, whose job also includes organizing roadside monitoring with mobile radar devices throughout the district - in consultation with the respective inspections.
The fastest car whose photo Wagner viewed reached 225 km/h under the gantry.
“Approval in Eastern Europe,” remembers Wagner.
Although two-thirds of all offenders from Irschenberg received a letter, this driver got nothing.
Wagner is a professional, but that annoyed him: "Unfortunately, we couldn't identify him."
You can read a detailed report on the episode with the four Arab tourists here.
