Although Stuttgart 21 (a railway and urban development project) is currently the city's hottest topic, Stuttgart also has other large-scale projects in the pipeline. One of which is planning the  Rosenstein tunnel, another is re-engineering the B10/B14 junction at Leuze.

Both projects aim at drawing traffic away from Stuttgart's residential side streets, currently used as shortcut thoroughfares, and back onto the B10 highway. Hyder Consulting GmbH Deutschland was tasked with planning these projects.

Hyder Consulting has been tasked with logging the existing conditions and designing all the traffic infrastructure. They are also designing the signposting, coordinating the construction phases and providing official traffic sign and lane marking plans.

The new B10 Rosenstein tunnel and re-engineered B10/B14 junction at the Leuze spa are part of a larger overhaul of the B10 between Stuttgart-Zuffhausen (Friedrichswahl junction) and Stuttgart-Ost (Talstraße junction). The B10 tunnel at Pragsattel opened in 2006. These two measures will finally close the gap along the B10 and give much needed traffic congestion relief to the surrounding road network. These are among the most congested roads in the Stuttgart area.

The Rosenstein tunnel is being jointly designed by WBI of Aachen and Boll und Partner of Stuttgart. WBI is responsible for the mining method sections while Boll und Partner is looking after the cut and cover tunnel sections. Boll und Partner is also working with the architects Wulf & Partner of Stuttgart to re-engineer the B10-B14 junction at the Leuze spa. Once again, Boll und Partner is responsible for the overall designs.

The new section of road, including the 1000m Rosenstein tunnel and a ramp of 300m, will be 1.56km long. The designs also require the section of Neckartalstraße near the Wilhelma Zoo and the Neckartalstraße-Pragstraße junction to be redone. This involves re-engineering a section of the tram line near Pragstraße to make room for the tunnel's on and off ramps. The tunnel's lowest point is determined by the local water table. It will mean raising the tram line and moving the Rosenstein tram stop to in front of the Wilhelma Zoo.

The B10 extension at the B10-B14 junction (Leuze) is approx. 660m long and joins at the B10 Rosenstein tunnel section of construction. The new third tunnel tube, at approx. 300m long, will run between Neckartal and Ufer streets alongside the existing two tunnels. The cut and cover construction method will be used for this tunnel, as well as for the re-engineering of the Uferstraße opening.

A short tunnel of approx. 85m is planned to connect the B10 to the B14 heading into town. This three-lane tunnel runs at a tangent to council waterworks' subterranean structures, tram tracks, existing pedestrian access paths and the so-called "Berger Sprudler" (mineral springs). Here too, the cut and cover construction method will be used.

During construction the existing pedestrian bridge will have to be made safe and the footpath suspended across Stadtbahnstraße dismantled. The tunnels currently leading towards Esslingen will be used for left-hand turns from Esslingen into the city centre. This will allow a new connection to Bad Cannstatt via a ramp onto the B14.

In order to cope with the projected traffic volume and to spread the traffic flow heading towards the tunnels, a further lane will be added to the B10 in the region of Uferstraße/Leuze tunnel. This will mean removing parts of a heritage-listed turbine house and altering existing public utilities (water tanks, substations etc.) of the Neckar waterworks Berg (EnBW). Both tasks will have to be completed alongside normal traffic flows with very little space to spare.

Hyder Consulting used card_1 to survey and design all the traffic infrastructure. Exchanging data with their working group (ARGE) partners was done entirely in the DWG format, without any data loss. Hyder Consulting's surface elevation plans provided the basis from which a scale construction model was built (1:200).

The project started in 2005 using card_1 version 7. Then, in 2010, while working on the "Leuze Connection" sub-project, version 8.3 was released. This proved to be an enormous step forward as this extremely complex project required keeping track of four levels of planning in the Neckartalstraße section.

At level -1, the Nesenbach (brook), with three large chambers, flows into the Neckar River. The entire volume of water flowing from the Stuttgart valley is drained into the Neckar River via this structure. This level of the designs also deals with the many gas, water, sewage, electricity and other pipelines which had already been relaid as part of preparatory measures to divert them  around the future construction site.

At level 0, Neckartalstraße opens into the Leuze tunnel in this section of the plans. At level +1, Cannstatt Street crosses tram tracks above the tunnel roof. At level +2, a large pedestrian/ bicycle suspension bridge straddles Cannstatt Street and the tram lines. And a large load plate, bearing the bridge's forces, lies at the base of the bridge's pylon.

DTMs of the existing structures were created in order to log the complex interrelationships between, and incursions into these subterranean structures. card_1's simple means of displaying the designs in 3D was extremely helpful when planning the almost 40 phases of construction, as the complexity of the four levels could be clearly visualised by the planners.

Stuttgart 21's plans submitted for planning permission provided the specifications for the project. The railway bridge over the Neckar River crossed by the Stuttgart 21 railway line intersects Neckartalstraße at the Rosenstein tunnel section of the designs. The position of the bridge's foundations, as determined by the S21 planning permission drafts, had to be taken into account when planning the bearing walls of the Rosenstein tunnel opening.

It is currently impossible to foresee when these projects will be carried out. Should both projects occur within the same time frame, there will be much to factor in, such as the site road for the bridge abutments and the working area for the bridge's foundations when constructing the Rosenstein tunnel and the Leuze junction.