BAB A 3, Noise Abatement Encasement Goldbach/Hösbach

In the Goldbach/Hösbach area, built-up districts are to be found along both sides of the BAB A 3 motorway, which are largely classified as residential or mixed/rural zones. Owing to the high traffic frequency, the minimal gaps between the built-up districts to the motorway and the unfavourable topographical Situation with a motorway running through the valley and housing located on the slopes, an encasement had to be provided for certain part-sections apart from the extensive noise protection walls already foreseen in conjunction with developing the 6-lane motorway. The encasement structure is planned as a closed concrete-glass system with a longitudinal structuring of the roof and outer wall areas. The directional carriageways are separated from each other by means of a continuous central partition. Each tube is to be provided with a folded roof. Windows set at the side in the roof area will cater for natural lighting. The amount of light needed for the carriageway section governs the size of window. In order to be in a position to fulfil these high demands, lighting strips are to be set up in the section both on the inside as well as the outside. In the transition and inner zones, windows located on the inside only are foreseen. The required window dimensions for the inside are 2.2 x 3.25 m and 2.2 x 2.7 m for the outside. The entire window areas for the encasement will amount to around 9,500 m². It is intended to use partly pre-stressed compound safety glass. The naturally lit encasement will be interrupted at the municipal boundary of Goldbach/ Hösbach and replaced over a length of some 185 m by a box cross-section, in which greenery will be planted. A new road is also to be constructed here and linked with the motorway by means of ramps. Artificial lighting is foreseen for this part-section. Thanks to the central partition wall along the entire length, it will be possible to make avail of the "piston effect" from the directional carriageways. As a result, no ventilation system will be needed under normal circumstances. However, artificial longitudinal ventilation with jet fans is foreseen in the event of tailbacks. The continuous partition wall also has the advantage that in the event of fire, the other carriageway will still be operational. In addition, a sufficient number of escape doors will be set up. The carriageways will be drained via ducts and transferred outside of the encasement structure via lines to receiving basins without outlets. There, fluids which have been polluted during cleaning procedures and accidents, which involved substances harmful to water, are collected and disposed of accordingly. The surface water falling onto the roof areas can be passed directly into the Aschaff which runs practically parallel to the motorway.

• Country: Germany
• Region: Bayern
• Tunnel utilization: Traffic
• Type of utilization: Road tunnel
• Client: Autobahndirektion Nordbayern
• Consulting Engineer: Ingenieurgemeinschaft Lässer
• Main construction method: Open
• Type of excavation: Encasement
• No. of tubes: 2
• Tunnel total length: western structure: 1,382 m two-sided; eastern structure: 364 m two-sided, 340 m one-sided
• Cross-section: 110 m² per tube
• Contract Volume: 125 mill. DM
• Opening: 2005