Swiss Bridge Maintenance: Insights and Challenges

Johannes: Today we talk about the maintenance process of bridges. In doing so, we speak with Jean-Marc Waeber from the Swiss Federal Roads Office, ASTRA. Jean-Marc Waeber works in the Road Infrastructure West department and leads the area of Technical Support. He is a qualified civil engineer and has been working at ASTRA for more than 16 years.

Welcome, Jean-Marc.

Jean-Marc:

Thank you, Johannes.

Johannes: Jean-Marc, can you first give us a brief overview of ASTRA?

Jean-Marc:

My name is Jean-Marc Waeber, I am located in the Road Infrastructure West department and lead the Technical Support West area, am a qualified civil engineer. Have been working at ASTRA for more than 16 years.

The Federal Roads Office “ASTRA” is an important part of the Federal Department of Environment, Transport, Energy, and Communication “DETEC”.

The organization of ASTRA consists of 7 departments.

Control and Finance, which is responsible for the finances of the office as well as risk and quality management;

Directorate Affairs, includes legal service and land acquisition, IT and translation service;

Digital Services, everything concerning IT;

Road Network, reviews and establishes all guidelines, directives and sets the standard of the national road;

Road Traffic, they are responsible for making traffic safer, cleaner, and more efficient. It is their task to continuously review and develop the road traffic law and the corresponding regulations;

and finally, both Road Infrastructures East and West.

The Road Infrastructure departments are responsible for the operation, maintenance, and expansion of the national roads of classes 1, 2, and 3. The national road network is divided into two areas East-West and five branch areas.

The national road network has a length of about 2,250 km and is complex, as it consists of about 4,600 structures, about 240 tunnels, and over 20,000 support structures.

Johannes: What is included in structures?

Jean-Marc:

That’s a good question. At ASTRA, when we talk about structures, we mainly refer to bridges. This includes viaducts, cantilever bridges, overpasses, and underpasses. Then there are the support structures, culverts, and cut-and-cover tunnels.

Johannes: Out of the many areas of responsibility you’ve just mentioned, we would like to focus on bridge maintenance today. What are scenarios where the replacement of a bridge becomes necessary?

Jean-Marc:

The replacement construction of a bridge can be necessary for various reasons. One of them is that the structure cannot reach its intended service life. This means that the construction of the structure was not carried out according to the rules of art.

Another reason is that the existing damages and defects are too large and that the cost/benefit ratio is no longer given.

However, there are cases where replacement construction is inevitable, even if the structure itself is still in an acceptable condition. This is the case when the capacity of the main axis is reached and the flow of traffic comes to a halt. To counteract this, the main axis is expanded by an additional lane. As a result, the clearance profile under the structure can no longer be guaranteed, and the structure must be replaced by a new one.

And in the latter case, the structure has reached its intended service life and is no longer capable of being maintained.

However, ASTRA always strives for the preservation of the structure. Only when all preservation possibilities and solutions have been exhausted is the structure replaced.

Johannes: What do you mean by main axis? What is the difference between the main route main axis and section?

Jean Marc:

The main axis always refers to the highway itself. The difference between the main axis and a section is when talking about a section, it only refers to a part of the main axis, such as a maintenance section.

Johannes: What is the expected lifespan of a bridge?

Jean-Marc:

The lifespan of a structure is about 80 years.

Johannes: So, one reason for a shortened service life is if the design or processing was not carried out according to the rules of art. Does it also happen that some damage mechanisms simply were not known back then / knowledge was not available?

Jean-Marc:

That is also a reason, that the knowledge about our building materials back then was just what they knew. Today it is no different with the new building material UHPC. Today it is assumed that this is dense and the answer to all our design problems. Whether this is the case, we will see in the next 20 to 50 years.

Johannes: To maintain a bridge, as you mentioned, for as long as possible, its condition must be regularly checked, and it must be decided whether structural measures are necessary. How does this process work?

Jean-Marc:

As you mentioned, Johannes, all damages and defects are recorded during the regular inspections, leading to a condition assessment report. This report also lists

Johannes: Today we talk about the maintenance process of bridges. In doing so, we speak with Jean-Marc Waeber from the Swiss Federal Roads Office, ASTRA. Jean-Marc Waeber works in the Road Infrastructure West department and leads the area of Technical Support. He is a qualified civil engineer and has been working at ASTRA for more than 16 years.

Jean-Marc:

As you mentioned, Johannes, all damages and defects are recorded during the regular inspections, which leads to a condition assessment report. This report also includes the proposed maintenance measures to address the damages or defects, with a timeline by when these should be assessed.

Johannes: I would like to go into more detail here. Can you explain more precisely who inspects, how often, and with what means?

Jean-Marc:

All structures that are our property are inspected every five years. These inspections are carried out by professionals who have been trained by us (civil engineers).

These are commissioned by our 5 branches. The inspections can be commissioned to third parties (engineering offices) or to the area units. However, it is up to the branches how they want to handle it.

The monitoring of structures is anchored in our guideline 12002 “Monitoring and Maintenance of the NS Structures”. Inspections are usually visual, “non-destructive” and without disrupting traffic. Should further investigations be necessary, we also commission testing laboratories to take samples from the structure.

Depending on the occasion and purpose, three types of inspections are envisaged:

Main inspection: the normal cycle of the inspection program every 5 years

Intermediate inspection: these are initiated if there are damages or defects that should be closely monitored, or if it will be a few years before the construction of the repair comes (annually or every 2 years).

Special inspection: After an unforeseen event (accident, natural disasters, etc.)

Johannes: You said “inspections can be commissioned to third parties or area units”. What are area units?

Jean-Marc:

To explain this, I need to elaborate a bit.

With the introduction of the NFA (New Financial Equalization and Task Allocation between the Confederation and the Cantons) in 2008, the Confederation became the owner of the national road network. Thus, the Confederation also took over the responsibility for the operational maintenance of the national roads.

The cantons have established so-called area units, which conclude performance agreements with ASTRA and provide numerous services for the national roads: winter service, cleaning, green maintenance, maintenance of the operational and safety equipment, as well as minor structural maintenance.

Johannes: What happens next? How is the inspection information handled? Who decides what to do?

Jean-Marc:

The decision on the repair or replacement construction of a structure is made by the project steering committee. This committee sets the strategy and the projects on the main route and decides on them.

For decision-making, the branches, in cooperation with the technical support, create a maintenance concept for the entire section. This includes the multi-year construction project as well as the resource and financial planning.

Johannes: So, the timing of the bridge maintenance needs to be aligned with that of the section. How far in advance do the branches plan here?

Jean-Marc:

To the first part of the question: Yes. The section, or as we say in ASTRA, the maintenance section, is always considered as a whole. As mentioned before, based on the condition assessment reports, the observations in the maintenance planning, a prioritization of the maintenance sections is carried out and when they need to be renovated. After the renovation of an entire section, our policy at ASTRA is: “No construction sites and no traffic obstructions on this section for the next 15 years”?

Johannes: What are the decisive components that necessitate the maintenance of a section?

Jean-Marc:

The causes can be varied. It can be the road surface, it can be structures, it can be safety defects, it can be the main axis no longer meeting standards. But primarily, our customer, the motorist, counts. They must always be safe from one point to another.

Johannes: A road section is to be renovated. What are the next steps until it is executed?

Jean-Marc:

In the first step, a project generation is created by our Maintenance Planning area of the branches. Based on various inspection reports, it defines the measures required for each specialist area (route, environment, structures, tunnels, geotechnics, and electromechanics). The maintenance planning then hands over the project generation to the branch’s project management. This sets up a project team.

The project team consists of the branch’s project manager, the client support, and the project authors (civil engineers, specialists from various fields). This team develops the individual project phases (preliminary design, final design, and construction phases) and submits them to my area (technical support) for review. Technical support checks the projects to ensure they comply with various legal bases (laws, regulations, standards of the NS, and norms). After a thorough review on our side, the project can be submitted for approval.

After our approval, the project team can start drafting the tender dossier and begin the tendering process to find a company.

Johannes: To understand the responsibilities and processes between the stakeholders more precisely. The client representation represents ASTRA and takes care of project management, communication, helps with contracts, etc.

The project author in the project team is usually an external civil engineering office that does the preliminary studies, design, etc.?

Jean-Marc:

Let me explain. The client supporter and the project author are both external engineering offices. The client supporter assists the branch’s project manager in their daily work. As you’ve already said, their activities are project management, meeting management, and they assist with accounting and contracts. The project author does exactly what you predicted, they conduct preliminary studies, design, etc.?

Johannes: You mentioned that “further investigations” are sometimes necessary? Does this mostly occur during the main inspection, intermediate inspection, or only during project generation?

Jean-Marc:

This depends on the individual case. The further investigations are carried out during project generation. Additional investigations are conducted during the design phase to obtain specific material characteristics at specific locations.

Johannes: A tender is issued, and the best offer from a contractor/consortium, in terms of quality and cost, is selected. What happens next?

Jean-Marc:

The construction company executes all construction projects of ASTRA considering the previously mentioned legal foundations.

After the construction work is completed, all project objects are accepted by the contractor, the project manager, and ASTRA’s maintenance planning. The accepted objects are returned to ASTRA’s ownership for maintenance planning. This closes the loop, and the cycle can begin anew.

Johannes: How is the project handed over to maintenance planning? (Documents? Inspection plan?)

Jean-Marc:

The project manager hands over the file of the executed construction. It includes: the actual executed plans of the structure, all important documents such as project basis, usage agreement, monitoring plan, statics, etc.

Johannes: Thank you, I believe the listeners have gained a good overview. I would also like to talk about the challenges ASTRA faces concerning maintenance. What are the biggest?

Jean-Marc:

The biggest challenges for ASTRA in the coming years will undoubtedly be climate issues and digitalization.

Especially the reduction of CO2 emissions and the management of energy consumption.

And not to forget: We have an aging infrastructure, and it is not getting any younger.

Most structures were built in the 1960s/70s. So, the majority of our structures are almost 60 years old and will need to be renewed in the next 20 years.

The big question is: How should this be done, and how can we do it without emitting more CO2 and using less energy?

One answer for ASTRA could be digitalized project planning BIM. Simplify planning and construction processes and save resources.

Yes, resources are also an exciting topic. As we already see and feel today, the search for new professionals is a huge problem because we lack skilled workers. The job market is dried up.

Therefore, we need today’s youth, who are motivated and looking for interesting, exciting challenges. Who help us bring our structures, all of which are prototypes, up to date again.

And who want to face the challenge. “How do we build and maintain our structures in the future? With what materials and equipment on the construction sites.”

Johannes: … and how are we preparing for the mobility of the future, keyword “autonomous driving”?

Jean-Marc:

I can say this about it. We at ASTRA are fully committed to advancing autonomous driving. Our three departments, Road Network and Digital Services, are working on developing the necessary directives, guidelines, and standards to ensure autonomous driving, and the Road Traffic department is developing the necessary laws and the associated regulations.

Johannes/Jean-Marc: Thank you for your attention.