Project Untertor Bridge
The Untertor Bridge is Bern’s oldest bridge crossing the River Aare and one of the oldest stone bridges in Switzerland. It is constructed primarily of regional tuff and sandstone. It was last extensively renovated between 1980 and 1982 and reinforced with a concrete slab. The planned renovations from 2029 to 2031 will address the damage to the historic railing anchors, the undersides of the arches, and the waterproofing.
Reasons to renovate
The railing anchors are damaged
The railing is rusting and the posts have cracks; both will be repaired, and the anchors will be replaced. In addition, the required load-bearing capacity must be retrofitted.
Waterproofing and bridge drainage system are not sufficient
The waterproofing is leaking in some places, and the drainage outlets are partially clogged. Water ingress has damaged the natural stone and joints. There are minor cracks on the undersides of the arches, and they are partially wet. Below the waterline, the piers consist partly of sandstone and partly of limestone blocks. The sandstone blocks show signs of spalling and sand deposits; in the area of the waterline, some joints are open.
The pavement is uneven along the traffic lanes and has damaged joints.
The pavement will be replaced, and at the same time, the street layout will be reconfigured to widen the sidewalk.
The utility lines are being replaced
The City of Bern and “Energie Wasser Bern” are taking advantage of the bridge renovation work to rehabilitate the sewer lines and replace the electricity, water, and gas lines at the same time.
The surrounding area will be enhanced
Along Altenbergstrasse, new benches will be installed on the paved area between the trees. The sidewalk, which currently runs directly along the riverbank wall, will be moved in front of the trees and widened. The bicycle parking spaces in front of the Landhaus will therefore be relocated to the other side of the street, between the trees.
Construction schedule
- Widening of the sidewalk on Altenbergstrasse
- Construction of the walkway next to the bridge for pedestrians and cyclists
- Road construction and utility line work, waterproofing, paving, lighting, railings
- Commissioning of the gas and water lines in the center of the bridge
- Road construction and utility line work, paving, railings
- Landscaping work to enhance the quality of the public space
- Dismantling of the walkway
Early 2029 – Early 2030
- Drying out the bridge
2030
- Restoration of the natural stone using a bridge inspection device
- Commissioning of the water line at the edge of the bridge
Early 2031
-1.jpeg%3F2026-10-12T09%253A02%253A54.524Z&w=3840&q=80)
Traffic restrictions
During construction, the Untertor Bridge will be closed for private motorized transport. Local traffic will be rerouted via the Untertor Bridge, while other traffic will be rerouted on a larger scale via the Kornhaus Bridge, Monbijou Bridge and Lorraine Bridge. Pedestrians and cyclists will cross the Aare on a walkway approximately three meters wide at the Nydegg Bridge. Bicycles must be walked across.
Starting in spring 2031, during the natural stone restoration, the bridge will be open to pedestrians and cyclists on only one side at a time. It will be closed to private motorized transport during this period.
Klösterlistutz and Altenbergstrasse will remain open to traffic during construction, though occasional restrictions are to be expected. The road will reopen during the eight-month dewatering phase.
Nice to know about the Untertor Bridge
Yes. During construction, the Untertor Bridge will be closed to motorized private transport. It will reopen during the eight-month drying phase. Starting in spring of 2031, while the natural stone is being restored, the bridge will be open to pedestrians and cyclists on only one side at a time. It will be closed for motorized private transport during this period.
Yes. You can cross the Untertor Bridge on foot or by bike at any time: initially via a walkway where bikes must be walked, and later directly across the bridge.
Yes. The shops and restaurants within the construction zone will remain open throughout the entire construction period and are accessible on foot.
Yes. The Untertor Bridge is listed in the Federal Inventory of Historic Transport Routes in Switzerland. The renovation is being carried out in close coordination with the historic preservation authorities.
The total cost is approximately CHF 8.74 million. The City of Bern is covering the main part of CHF 7.74 million, while “Energie Wasser Bern” and the telecommunications providers are covering the remaining CHF 1 million. Voters approved the funding on May 18, 2025.
Building ownership Untertor Bridge
Renovates the bridge structure (railing, natural stone, paving), widens the sidewalk, and replaces the municipal drainage system as well as the connections and traffic signal systems.
