|traffic connection||B304 , B299|
|place||Altenmarkt an der Alz|
|Number of tubes||1|
|cross-section||95 – 108|
|Largest coverage||40 m|
|Client||Federal Republic of Germany|
|building-costs||€ 30 million for the entire bypass|
|start of building||2017|
|Plans||Motorway Directorate South Bavaria|
The Aubergtunnel is a finished in 2020 road tunnel of B304 to the bypass road from Altenmarkt an der Alz . In particular, it relieves the confusing and narrow traffic junction "Schneeweißeck" with the B299 . 
The confluence of the B304 with the B299 lies in the middle of the densely built-up center of Altenmarkt. It is winding and difficult to see and is a hot spot for accidents. With over 15,000 vehicles daily, the traffic load in the Altenmarkt thoroughfare is relatively high. A solution to the traffic problem through construction work on the Schneeweißeck is ruled out due to the local conditions.  The tunnel solution eliminates the problem and enables a partial bypassing of the Altenmarkt community. The complete bypass is provided as a further measure in the requirement plan for the federal highways.
The B299 federal road is an important north-south traffic axis; in its southern part it connects the A94 motorway near Altötting with Altenmarkt. Then it goes over to the south-leading part of the B304, which runs to the A8 near Traunstein . Because of the numerous industrial and commercial operations in the region, it has a high number of trucks. The B299 runs in the Alz valley right through the neighboring town of Trostbergand the north of the municipality of Altenmarkt. About halfway between the two motorway connections, the B304 branches off to the west in Altenmarkt and connects the region with Munich. For a long time, there have been considerations about bypassing and relieving the existing road network. With the completion of the Auberg tunnel, a major bottleneck will be eliminated. When connecting to the existing road network, options for future expansion plans are taken into account.
The total length of the two-lane road construction measure is 1.5 km. In the west of Altenmarkt there is a junction-free junction from today's B304 to the new tunnel. The remaining section of the old federal road will serve as local access for local traffic. In the north of Altenmarkt, the tunnel will be connected to the existing road system via a roundabout. An operations building and parking areas for rescue operations are being built right next to the north portal. The tunnel is designed for a total carriageway width of 7.50 m (2 × 3.25 m) and a height of 4.50 m. There are also two side strips of 0.25 m each, a central strip of 0.5 m and two emergency walkways of 1.0 m each. 
The symbolic groundbreaking ceremony took place on April 24, 2017.  The tunnel breakthrough was celebrated on October 15, 2018.   The tunnel is driven from north to south-west. The construction site equipment is located at the north portal. The mining work is carried out conventionally in partial cross-sections. The excavation is mostly carried out using an excavator, blasting is only partially planned. Immediately after the cavity has broken out, temporary securing is carried out, after which the shell is sealed. The tunnel has been open to traffic since November 2, 2020.  The official opening is scheduled for early 2,021th 
- Auberg tunnel (pdf) . In: Bavarian State Ministry for Housing, Building and Transport . Retrieved January 21, 2019.
- The wait is over: groundbreaking at the "eye of the needle"! . In: rosenheim24.de . April 24, 2017. Retrieved January 22, 2019.
- Through at Aubergtunnel in Altenmarkt . In: Marti GmbH Germany . October 14, 2018. Retrieved January 22, 2019.
- Auberg tunnel in Altenmarkt: breakthrough made + video . In: Passauer Neue Presse . October 18, 2018. Retrieved January 21, 2019.
- Exclusive insights before the trial opening of the Aubergtunnel. Chiemgau24de, November 2, 2020, accessed on December 3, 2020 .