mit expert Otto Noger from ASTRA (Federal Roads Office)
A Swiss motorway maintenance planning section, or U-Plans, runs roughly 3 x 5 kilometers on average and can take about seven years from planning to construction start. Otto Noger, branch head at Switzerland’s federal roads authority ASTRA in Winterthur, explains how maintenance planning for national motorways works, what role inspections play, and why concrete, pavement, and electromechanical systems all age on completely different timelines.
How structure inspections actually work
ASTRA’s maintenance planning unit inspects its network on a five-year cycle, split into annual segments so the entire territory is covered every five years. Structures such as bridges are inspected visually, historically almost entirely by eye, but increasingly supplemented today by drones for bridge underside inspections and, in some cases, sensors and material investigations such as drill cores.
External inspectors work from a clear brief defining what to check and which points on a given structure are critical. The inspection data then goes to ASTRA for evaluation. If cracks or water ingress appear on a structure, that finding triggers closer, ongoing observation.
Who decides when the finding is unclear
Inspectors receive a clearly defined task, but how they arrive at their result is left to them. They are expected to propose additional tools when a more precise assessment is needed. The final decision, however, always rests with whoever is responsible for making it, and that person has to judge how much information is enough to support a sound decision.
For electromechanical systems such as fire and safety installations, condition can be checked fairly definitively, for instance by triggering the safety responses directly. Looking into concrete or subsoil is far less conclusive, and a fully certain answer is rarely possible. That is where experience matters most, and Otto Noger sees human judgment remaining central for the foreseeable future, rather than being replaced by automated assessment.
Why rehabilitation almost always happens under live traffic
Because the national motorway network is Switzerland’s primary traffic system, load cannot simply shift to lower-tier roads during rehabilitation. Greenfield construction has essentially disappeared; nearly all projects now rehabilitate existing infrastructure, sometimes with modest capacity additions. That pushes much of the construction and investigation work into night shifts.
- Emergency measure (like-for-like replacement): about six months to completion
- Smaller measure: roughly 2 to 3 years from planning to completion
- Larger U-Plans project: about 7 years to construction start, sometimes 15 to 20 years total
Maintenance planning as a balancing act between components
Concrete outlasts pavement and electromechanical systems by a wide margin; some electronic components have a notably short service life. To avoid subjecting drivers to constant construction disruption, ASTRA targets roughly 15 years of maintenance-free operation per section. Experience has also shown that a single construction zone should not exceed about five kilometers, since longer stretches measurably increase driver fatigue and accident rates.
A 15-kilometer U-Plans section is therefore split into three five-kilometer segments, each rehabilitated in a separate traffic phase. Planning must also account for regulations that may have changed since the last intervention, such as updated noise-protection or environmental requirements.
You have to start the right project tasks at the right moment. That is really the art of maintenance planning. — Otto Noger, ASTRA
Why yesterday's standard solutions are being replaced
What once counted as sound engineering practice is not always considered adequate today. Concrete cover over reinforcement used to be calculated at around two centimeters; today it is five centimeters or more. Gerber hinges were once seen as an elegant, efficient solution, but their interior condition is practically impossible to inspect, even with a drone. As a result, bridges built with this detail are largely being replaced. Monolithic rock anchors also revealed unexpected corrosion behavior in practice and are no longer used for that reason.
According to Otto Noger, the fastest-moving area today is not concrete but operational and safety equipment. Where tunnels once had isolated individual systems, entire stretches of the network now run continuous hard-shoulder running, speed harmonization, and hazard warning systems. These systems are highly complex and age far faster than concrete or asphalt, though Otto Noger notes that some electronics have stayed in service for over 30 years, provided spare parts remain available.
What the coming years will bring
Most of Switzerland’s national motorways were built starting in 1960, putting the network roughly at the halfway point of its approximately 100-year design life. A structure typically undergoes comprehensive rehabilitation once or twice over that lifespan; after a first major wave in the 1990s, a new wave of structures is now approaching renewal age. At the same time, the nature of the infrastructure is changing: roads are increasingly becoming networked systems that must be operated like a factory, with complex, electronically controlled processes.
With limited land available and little public appetite for new roads, squeezing more capacity out of the existing network requires better and more precise inspection data, in Otto Noger’s view. Sensor deployment will therefore intensify, and as data volumes grow, the ability to select and prioritize the relevant data will become increasingly important.
FAQ
What is a U-Plans in Swiss motorway maintenance?
A U-Plans is a maintenance planning section of the Swiss national motorway network, typically around 15 kilometers long, based on the original construction sections. According to Otto Noger, a larger U-Plans project takes about seven years from planning to construction start.
How often are motorway bridges and structures inspected in Switzerland?
Structures are inspected on a five-year cycle, with one segment of the network covered each year so the full territory is inspected every five years. Inspections are primarily visual and increasingly supplemented by drones, sensors, and material testing such as drill cores.
Why are Gerber hinge bridges being replaced?
Gerber hinges were once considered a clean, efficient engineering solution, but their internal condition cannot be reliably inspected, even with drone technology. Because a dependable condition assessment isn’t possible, ASTRA is replacing most bridges built with this detail.
