Noise remediation of national road: proportionality of noise barriers and WTI calculation with road surface; remittal for supplementation of the facts

Facts

The Federal Roads Office (ASTRA) on 21 September 2015 asked the Federal Department of the Environment, Transport, Energy and Communications (DETEC) to approve the detailed project 'National road N2 noise remediation project Sursee-Rothenburg'. The project provides for the installation of a low-noise road surface Type SDA 8 Class A (except for the tunnel in the municipality of Eich), but no noise protection structures. At the same time, ASTRA applied for exemptions for properties where the immission limit values would still be exceeded.

The municipality of Schenkon filed an objection during the public consultation and requested the construction of the noise barrier Schenkon Dorf (East) and the noise barrier Seemattbrücke (middle wall), possibly with cost participation by the municipality. DETEC approved the detailed project on 4 April 2018, granted exemptions and dismissed the objection.

The municipality of Schenkon appealed this decision to the Federal Administrative Court on 4 May 2018. The court joined the proceedings with the appeal of the municipality of Eich and other parties involved and dismissed the appeals by judgment of 20 February 2019 (A-2587/2018).

The municipality of Schenkon lodged a public law appeal with the Federal Supreme Court on 27 March 2019 and requested the annulment of the lower court's judgment and of the plan approval, alternatively the remittal to DETEC or the lower court for further clarification of the facts, alternatively the construction of the requested noise protection structures. ASTRA requested dismissal; DETEC and the Federal Administrative Court waived a response; the Federal Office for the Environment (FOEN) considered the lower court's judgment to be compliant with environmental law. The President of the I. Public Law Division rejected the application for suspensive effect by order of 13 June 2019.

The dispute concerns in particular whether, in the economic viability assessment (Index of economic viability, WTI) for the noise barriers, the new road surface had to be included, and whether the applied cost benchmark of CHF 1'700.--/m2 for the middle wall on the Seemattbrücke is accurate. The lower court had performed a plausibility calculation and dispensed with further investigation.

Considerations

The appeal is admissible: there is a final decision of the Federal Administrative Court in a public law matter (Art. 82 lit. a, Art. 86 para. 1 lit. a, Art. 90 FSCA). The municipality has standing under Art. 89 para. 1 FSCA, as it represents significant public interests such as the protection of residents from harmful immissions and a large part of its residents are affected. The Federal Supreme Court does not enter into the appeal against the DETEC decision of 4 April 2018, which was replaced by the judgment, due to the devolutive effect, but this decision is deemed to be contested as well.

Exemptions under Art. 17 EPA and Art. 14 NAO are to be applied restrictively. The remediation obligation (Art. 16 EPA, Art. 13 NAO) is owed only insofar as it is technically, operationally and economically viable. In plan approval proceedings, not all alternatives must be designed in detail; obviously disproportionate variants may be excluded summarily. The WTI is an aid developed by practice (WTI = effectiveness * efficiency / 25; sufficient from 1.0), but it does not replace a comprehensive proportionality assessment with qualitative criteria.

According to the Technical Guideline on Project Planning and Annex 4a to the Guide on Road Noise, measures with a common area of effect must be assessed in their interaction. The Federal Supreme Court nevertheless holds that a combined WTI calculation with surface replacement is not mandatory in every case. Since low-noise surfaces are installed as standard on national roads, the surface may be disregarded in the calculation for a noise barrier with a clearly insufficient WTI; a combined calculation is carried out only in the case of a marginally insufficient WTI (0.8 to 1.0). The FOEN, as the specialist authority, supports this practice, which is why the Federal Supreme Court does not depart from it. With a WTI of 0.2, forgoing the combined calculation is not contrary to federal law.

With regard to the cost benchmark, there are different approaches: the…