A8 “Enztalquerung” near Pforzheim: Mega construction site takes longer and costs more

As Autobahn GmbH Südwest announced at the 13th meeting of the project advisory group, completion of the entire project is now scheduled for the end of 2027 – about a year later than planned.

There are essentially two reasons for the delay: Firstly, the demolition method for the old Enz Bridge had to be adjusted in 2023, which affected traffic flow and thus the entire construction process. Secondly, the subsoil on the so-called Karlsruher Hang turned out to be much more complex than expected. Unexpected water retention , which was not apparent in the preliminary investigations, required additional measures to stabilize the soil and the embankment. This work not only delayed the schedule but also affected the construction costs , which were originally estimated at around 340 million euros. An updated cost forecast is currently being prepared.

Despite these challenges, the major project is progressing well overall. The new route will be significantly safer and more efficient in the future. For example, the elevation gain along the route will be lowered by up to 13 meters in some areas or raised by up to five meters – resulting in a significantly flatter route and thus greater traffic safety.

Important construction phases are scheduled for completion this year. These include the construction of the new Enz and B10 bridges in the direction of Stuttgart, the completion of the 380-meter-long noise protection enclosure at the Kieselbronner Kurve, and the landscaping of the "Hagenschieß" green bridge. Asphalt paving in the area of ​​the so-called Stuttgarter Hang is also scheduled for 2025.

A key milestone is expected in early 2026 : Traffic in both directions will then be diverted to the newly constructed Stuttgart-bound lane. This will represent a further step toward regular traffic flow.

The expansion affects an approximately 4.8-kilometer-long section of the A8 between Pforzheim-Nord and Pforzheim-Süd. The goal is to expand the currently four-lane motorway to six lanes, particularly in the so-called Pforzheim Depression with its steep gradients. A total of eight new bridges will be built as part of the project. The Pforzheim-Ost junction will be completely rebuilt and significantly improved in capacity. At the same time, the B10 federal highway will be expanded to four lanes in this section.

To improve noise protection for residents, noise barriers, noise enclosures, and sound barriers are being built. The "Hagenschieß" green bridge provides an ecological crossing aid for wildlife and improves biotope connectivity in the region. The overall package is complemented by modern drainage systems, stormwater retention basins, and the new Enztal-Süd parking and restroom facility, which will offer 30 additional truck parking spaces in the future.

Even before the actual construction work began, a dynamic traffic jam warning system was put into operation. It features radio warning systems in several languages, among other things. The goal is to provide early warning of traffic jams and traffic flow, especially for heavy goods vehicles, and thus prevent accidents.

With the completion of the project, one of the last bottlenecks in Baden-Württemberg's motorway network will be eliminated. The expansion of the Enz Valley crossing is intended not only to improve traffic flow but also to permanently increase road safety and noise protection in the region.

The A8 is considered one of Germany's most important east-west connections. The section near Pforzheim is characterized by deep valleys, steep sections, and bottlenecks—a combination that makes it one of the most congested and accident-prone stretches of motorway in Baden-Württemberg.