Project duration: 2007 - 2013

Location: Linz, Upper Austria

Category: Environmental Assessment Study (EAS)

Client: ASFiNAG


Description of project

To relieve the city center of Linz from traffic, a new highway section is erected, having major parts subsurface. The route leads from the “A7 Mühlkreisautobahn” motorway across the “Westbrücke” bridge into the “Waldeggstrasse” (cut and cover section), followed by a mined tunnel under the “Freinberg” to the banks of the Danube River. The Danube will be crossed by a suspension bridge leading directly into the “Pöstlingberg” Tunnel. Within the assessment study, the effects of the project during the construction and operation phases on air quality were evaluated. Long-term and short-term mean values for NO2 und PM10, as well as the deposition of Nitrogen and airborne dust, were calculated.

To be able to account for all the projected shifting of road traffic, detailed dispersion simulations for NO2 and PM10 for the entire urban area of Linz were carried out in the course of the assessment. The street-level resolution of emissions within the model allows for assertions about increased and decreased pollution concentrations even within the secondary road network. A special focus was put on pollutant dispersion in the vicinity of tunnel portals to assess the pollution.

Together with ventilation designers the ventilation concept for tunnels and cut-and-cover tunnels was developed through variant-studies. For the protection of residents, the use of environmental filter systems for the cut-and-cover tunnel and the western tube of the “Freinberg” tunnel were investigated. It turned out that a traffic dependent pollution management at the portals via a stack is sufficient in order to fulfil the air quality requirements.

Additionally, the effects of pollution reducing measures such as speed limits and noise barriers were considered for different sectors within the project area.

Both emissions and pollution concentrations during construction were calculated based on specifications of the construction concept. Excavation material from tunnels is transported by ships on the Danube, which helps to avoid numerous truck-runs within the inner city´s roads. In addition, NO2- und PM10 concentrations from construction activities were determined and abatement measures were developed.

All calculations were supported by data from a comprehensive air quality measurement campaign within the A26 project area.


Work load: 

  • Environmental assessment study
  • Air quality measurements