Fog warning system for the A8
2018-02-26 10:37
by Dürr Group GmbH
The motorway

The motorway A8 is one of the most important main road arteries in South Germany. The motorway between the Lämmerbuckeltunnel and Ulm leads over the Swabian Alb which is the biggest complete Karst area in Germany. There are many caves in this area. Eduard Mörike, a well-known lyricist from Ludwigsburg wrote the saga “die schöne Lau” all about this beautiful region, the “Blautopf” (a crystal clear blue spring) in the Karst area. Even Hans Christian Andersen wrote the story of the little mermaid, inspired by this area. Until the first fog warning system was installed in 1992, this area of the A8 motorway, to the west of Ulm was a place where many accidents occurred. In this area we often experience sudden fog banks which cause very poor sight. The installation of the fog warning system led to a clear decrease in accidents.
Traffic and weather conditions can be viewed on the following website:

Construction stage "West"

The A8 leading through and over the Swabian Alb is being constructed into a six-lane motorway with 3 lanes in each direction. However the section “west” will remain a four-lane section, i. e. 2 lanes in each direction. This section reaches from the Alb-ascent from the Lämmerbuckeltunnel to the European Watershed at a height of 785m above sea level, which makes it one of the highest motorway points in Germany. On this side of the watershed, the Swabian Alb belongs to the catchment area of the Rhine – the water flows into the North Sea. The rain that falls south east of the Swabian Alb falls into the Donahue and flows into the Black Sea.

The blind operation

All cables for the display points M01 – M04 have been layed. The variable message signs are not fully working yet. They are still being tested, as also the communication links and the traffic computer sub centre by the road works company of Dornstadt. Still, all sensors are fully functioning and giving feedback over traffic conditions, weather conditions as also road and system conditions. The sensor data gives the central computer, i. e. the car driver the possibility of looking ahead. Information concerning traffic jams or poor weather are sent to the relevant display points. The display points confirm the carrying out in blind operation but the traffic signs on the street remain black. When all tests have been completed, the operator will switch the cross sections to normal operation.

The communication

There are fog measuring points between the display points, especially in the west section. The sensor data is sent by decentralised communication interface through glass fiber ring busses, which means redundant paths lead from the section stations located by the sign bridges, collecting information to be transmitted to the so called “Isle bus”. The connection between the traffic sub centre and the Isle bus is made by our “communication computer Isle bus” type KRI2b. The computer has a redundant power adapter and double network interface. The road stations are implemented in integrated design which means that all functional groups, traffic and environmental data collect, as also variable message sign control are all summarized through the same hardware. So the data of the brightness sensors are available for the control of the variable message signs. The central computer can chose between central and local brightness control. To avoid dazzling the vehicle drivers, a large number of brightness levels are selectable.

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