Full closure of Mainstraße for seven weeks
19.09.2025 – From September 29, driving in Offenbach's east and city center will be a great test of patience. The Mainstraße section between Friedhofstraße and Bürgel will have to be fully closed in both directions for seven weeks over a length of 200 meters. The work will take place at the level of the "Die Grünen Haus" and should be completed by November 17 if the work proceeds according to plan. The detour will be via Arthur-Zitscher-Straße, Mühlheimer Straße and Kettelerstraße. The Main cycle path is not affected by the closure and can still be used. The city will provide information about the construction work and the development of the Innovation Campus in connection with it on September 24, 7 p.m., in the Rumpenheim community center.
The reason for the closure is extensive work by Stadtwerke Offenbach Innovationscampus GmbH & Co KG to connect the Innovation Campus, which is of enormous importance to the Offenbach population. The focus here is on the relatively complicated construction work for connecting the sewer. The construction site will also be used to lay water pipes for the water supply association in the city and district of Offenbach (ZWO) and empty conduits for Energienetze Offenbach GmbH (ENO) to expand Offenbach's electricity grid.
Lord Mayor Dr. Felix Schwenke is aware of the very severe and unpleasant impact on car and bus traffic and is therefore commenting on a construction site as an exception. He emphasizes: "The closure will cause a great deal of congestion and therefore naturally also frustration for car drivers and bus passengers. I am sure that many people will ask themselves: Why is this being done at all? Why is it a full closure? Why does it take seven weeks? Was it at least planned properly?"
Mayor Schwenke says: "Two things were important to us in the planning: 1. if at all possible, vacation periods should also be used for the closure, as there is usually less traffic. 2. as much work as possible should be coordinated in order to avoid multiple closures, which would have meant even more significant obstruction." In fact, the applications for the three construction measures were originally submitted for different dates, meaning that the utilities would have carried out this work independently of each other, i.e. one after the other and only later in the year. "Now we have at least managed to carry out three construction measures at the same time and also use the fall vacations for this. We can also start a little earlier than originally planned. I am fully aware that many commuters, families, care services and other people affected will not be able to switch to bikes at will. But by starting earlier, the weather will be a little better, at least at the beginning, for all those who are able to switch to bikes. In this respect, every effort was made during the planning phase to take the negative effects seriously and limit them."
The duration of the full closure is mainly due to the fact that large rainwater and wastewater sewers have to be laid up to six meters below the carriageway using the open construction method. The wastewater sewer will be connected to the city's main sewer, which is historically very deep there. In future, the rainwater will be discharged into the Main. In order to prevent the Main water from backing up, a concrete weir tower with a diameter of three meters will be installed around eight meters deep into the ground on the Innovation Campus. In simple terms, this creates a kind of gigantic backwater flap that is connected to other shafts and pipes.
ENO is using the full closure to simultaneously close a gap in its new 110 kv ring network to expand the electricity grid. The expansion of the capacity of the 110 kv ring network is necessary so that the electricity grid can supply both people and companies in the city with sufficient electricity in the long term. While data centers in particular have high energy requirements for companies, which are a direct consequence of the massive use of data by the population, it is the constantly growing electricity consumption of private households, including that of heat pumps and electric cars. The sensible increase in solar cells on roofs also requires the entire grid to be modernized so that the power supply remains stable at all times.
"Because the excavation pit is so exceptionally deep due to these measures and very large construction machines are being used, a full closure is unfortunately unavoidable, I had to be convinced," says Schwenke. For safety reasons, appropriate barriers and protection against the excavation pit collapsing are required. For this reason, it is not technically possible to restrict the closure to just one lane - Mainstrasse must be completely bypassed at this point. The detour will be via Kettelerstraße and Mühlheimer Straße, where major traffic jams can be expected during this time. "Due to this situation, we as the city have not approved any further construction sites on the detour route during the closure of Mainstrasse," says Mayor Schwenke with regard to the expected traffic obstructions.
Information event on the development of the Innocampus and the construction work:
"Of course, it is legitimate to ask whether the restrictions ultimately serve a sensible purpose. After all, citizens keep asking what exactly is happening on the Innovation Campus. For this reason, there will be an information event on Wednesday, September 24, at 7 p.m. in the Rumpenheim community center. There will, of course, be room for all questions relating to the closure." Mayor Schwenke will also be answering questions from the public. As an introduction, Samson and BioSpring will inform the general public about the status of their projects for the first time. Mayor Schwenke will show on a slide what the Innocampus will look like in the end. ENO will also be available to answer questions about the expansion of its 110 kV grid. In addition, flyers will be distributed in the districts of Bürgel, Rumpenheim, An den Eichen, Im Eschig and Waldheim, whose residents are particularly affected by the closure.
Date: Wednesday, September 24, 7 p.m.
Location: Rumpenheim community center
The information event will take place on the same evening as the information event on chlorine in drinking water with Mayor Sabine Groß. This could not be avoided due to the week of the city council meeting, the date of the lockdown from September 29 and the topicality of the issue of chlorine in drinking water. While the construction activities of Samson and BioSpring are of interest to the entire city, the chlorine in drinking water mainly affects the western areas of the city, while the closure of Mainstrasse mainly affects the eastern areas. In this respect, the two events are aimed primarily at different audiences.
Background to the development work for the Innovation Campus:
A completely new development for electricity, energy, heat, water and wastewater is required for the Innovation Campus, as the infrastructure that still exists there from the times of former chemical production is outdated and no longer meets today's requirements. The old sewer of the former Hoechst plant is also no longer compatible with today's existing sewer network - which is why it would not be possible to use the Innovation Campus without completely renewing the sewers and pipes. The 36-hectare site is currently being developed into a new attractive location for future-oriented companies. The companies Samson and BioSpring are already in the process of settling there. With them, new industry and in some cases highly qualified jobs are returning to Offenbach for the first time in decades. The first employees have been working at the new Samson site since the beginning of August 2025, producing positioners "made in Offenbach". Step by step, more and more parts of the Samson plant will go into operation until the plant opens completely in 2026. BioSpring has also started building its first production facility in the meantime.
"It is important for the population that the return of companies is not an end in itself for some abstract 'economy'. We can be both happy and proud that companies and jobs are coming back to Offenbach. All long-established Offenbach residents are aware of the difficult financial situation our city has been in for a long time. This has had an impact on people's lives in every nook and cranny. We want to and must change this. This can only be achieved with more jobs and more companies," says Lord Mayor Schwenke. He recalls that the construction of the S-Bahn, from which the population has now benefited for decades, was also associated with considerable restrictions. "The attitude of 'I'm not against more jobs, but I don't want to see any of this' doesn't work in real life. You have to be that honest. Our aim was and is to keep the restrictions to a minimum. But now comes a particularly difficult phase of the development work," says the mayor.
In March 2025, the magistrate and city council created the final legally binding building rights for the development of the public areas of the Innovation Campus, which also includes the construction of the canals. INNO Innovationscampus GmbH & Co KG is developing and marketing the site on behalf of the City of Offenbach.
Once the Samson and BioSpring plots had been supplied, partly in their final state and partly with interim measures, the final development work on the public areas of the Innovation Campus began in August 2025. After setting up a large construction site with office and sanitary containers, the first task from the end of September will be the sewer construction and pipeline work for electricity, water and wastewater, which will require a temporary full closure of Mainstrasse. The underground measures will be followed over the course of next year by the innovation belt, as the new main development axis along the commercial areas is called, new cycle connections and then, in 2027, the traffic connection of the site to Mühlheimer Straße. The existing junction of Mühlheimer Straße and Untere Grenzstraße will be expanded for this purpose. There will then be a second and final restriction for the public due to the Innovation Campus.
Mayor Schwenke describes the end result of all the work: "In the end, it will not just be a measure for companies. The site has been completely closed off for over a century. When we are finished, all Offenbach residents will be able to cross the area via roads, cycle paths, footpaths and new squares. It will be made accessible to the entire public and landscaped. Around 140 trees are to be planted in the Innovation Belt section alone - a big difference to before, when the area was completely sealed."
The general contractor has currently promised to complete the public development, including access to the innovation strip for the public, by the end of 2027 if everything goes according to plan. After that, the area will also be made accessible to the public in other places, such as the old park. However, the timetable for this will only be drawn up once the currently prioritized development has been completed, probably by the end of 2027.