Reference: A8 Tunnel Giswil

The Giswil Tunnel is a single-tube tunnel with two-way traffic. It is part of the A8 national highway in Switzerland. The tunnel is 2066m long and has a 2.5% gradient from north to south. The Giswil Tunnel was one of the first road tunnels in Switzerland to be equipped with a parallel safety tunnel.

The ventilation system consists of longitudinal ventilation with mid-point extraction. A local smoke extraction system with controllable dampers is installed for emergency ventilation. The airflow along the carriageway can be actively controlled with jet fans. The safety tunnel has a pressurisation system to keep it smoke-free.

The Giswil Tunnel was opened to traffic in 2004. Dr. Riess was involved in the project as project manager for tunnel ventilation from 1997 to 2004.

Detailed Design Tunnel Ventilation
Detailed investigation of the ventilation control system in normal operation and smoke control conditions
Specification of the ventilation control system
Procurement of axial and jet fans as well as exhaust dampers
Bid evaluation and recommendation for contract award
Factory acceptance tests
Technical site management for tunnel ventilation
Commissioning, acceptance tests, control system tests
Supervision of fire tests, evaluation of results

The refurbishment project was developed in 2023 and 2024. Riess Ingenieur-GmbH was responsible for the tunnel ventilation design.

Detailed Design tunnel ventilation
Detailed Design egress tunnel pressurisation
Ventilation control specifications
Immediate measures: replacement of damper actuators

The following images provide some impressions of the tunnel construction. Additional photos were added from 2023 to 2025 showing the refurbishment project.