Straßentunnel

Straßentunnel is a type of tunnel dedicated to road traffic, located underground or submersed, enabling a route when surface alignment is impractical due to urban density, geological obstacles, or watercourses. They range from short urban underpasses to long mountain or city-center tunnels. The main construction methods are cut-and-cover, where a trench is excavated and the tunnel structure built at shallow depth, and bored tunnels, which are excavated through rock or soil with tunnel boring machines and then lined. In some cases immersed tunnels are used, typically for crossing water bodies, though this method is less common for road traffic than for rail.

Twin-tube designs house traffic in separate bores for safety, with cross-passages for evacuation and emergency egress. They are equipped with ventilation systems, fire protection and detection, lighting, drainage, flood barriers, emergency telephones, cameras, and variable message signs. Control systems manage lane use, speed, incident response, and ventilation to minimize smoke propagation.

Design and construction involve geotechnical assessment, groundwater management, tunnel lining, and structural support. Urban tunneling requires mitigation of surface settlement, traffic disruption, and environmental impact. After opening, ongoing maintenance includes inspection of lining, ventilation, electrical systems, and safety equipment, with regular safety drills and compliance checks according to national and European standards.

Straßentunnel play a key role in modern transportation by enabling continuous routes, reducing surface congestion, and lowering noise and air pollution at ground level, while introducing challenges in safety management and lifecycle costs.