Ever wonder how Munich keeps its Autobahn flowing? Today we are standing before the Allacher Tunnel. It is more than just a passage. It’s a critical artery of Munich’s traffic network. Officially named Tunnel Allach, this Autobahn tunnel lies in Munich’s northwest.
Opened in 1998, the Allacher Tunnel guides the Munich Autobahn ring road with six lanes. The Allacher Tunnel stretches 1,030 meters. It was constructed using the cut-and-cover method. Above the tunnel, several roads and paths run. Even the Munich to Treuchtlingen railway line crosses overhead.
The Allacher Tunnel also facilitates the crossing of the Würm River. Just west of the tunnel entrance, the Eschenrieder Spange branches off towards Stuttgart. The tunnel’s construction cost 264 million Deutsche Marks. Construction started in 1996 and concluded in 1998. Each tube measures 16.10 meters by 4.80 meters.
Interestingly, the Allacher Tunnel has an automatic height control system at its entrances. This system prevents vehicles taller than four meters from entering. If a vehicle exceeds this height, the tunnel automatically closes in that direction. This protects the Allacher Tunnel from damage caused by oversized trucks.
But that’s not all. The section of the A99, where the Allacher Tunnel resides, is a notorious bottleneck. This often leads to traffic jams. Currently, there are modernizations of the ventilation systems being prepared. Also, cable strands will be newly installed. This is needed for the future. The upgrade will temporarily open the side strips inside the Allacher Tunnel. This should increase capacity.
Looking ahead, the Federal Transport Infrastructure Plan for 2030 lists a complete expansion of the section to eight lanes as a priority. A new tube for the eastbound direction is planned. This expansion might require demolishing existing residential buildings. The existing tubes would then serve the westbound A99a/Eschenrieder Spange or south/west A99 traffic.
The A 99 Autobahn ring is one of the busiest roads in Bavaria. Its location is important. It is a central element in Bavaria’s Autobahn network for the capital city. The Allacher Tunnel runs through this area. The Allacher Tunnel has two tubes. Each one is for one direction. It goes under several streets. It also goes under the railway and the Würm river.
Daily, about 132,000 vehicles pass through this section. During peak times, especially rush hour, the Allacher Tunnel becomes a chokepoint. The Autobahn GmbH of the German Federation is planning to renovate the Allacher Tunnel. The tunnel walls will be repaired. New operating technology will be installed. Drainage systems in the tunnel will be renewed. The renovation is necessary. It has been more than two decades in operation.
To relieve traffic, the Autobahn Suedbayern is planning a temporary side strip release during the tunnel renovation. This will be between the interchanges Munich-Allach A 8 and Munich-Feldmoching A 92. The side strips can become temporary fourth lanes. Cables and lines of the tunnel operating technology must be relocated for this. They will be put in a newly built route on the tunnel surface. This cable route includes six cable houses. These will be newly built on the tunnel surface.
The project is currently in the planning approval phase. The application documents were submitted at the end of 2020. Construction is expected to take eight years. The Allacher Tunnel will remain open with at least two lanes in each direction during construction.