Aesculap-Platz Pedestrian Underpass

Task definition

The road construction measure – New construction traffic circle Aesculap - Platz – is, next to the Kreuzstraßentunnel, the centerpiece of the new traffic routing in Tuttlingen. In this traffic circle the federal highways B311 and B14 are merged.

Since the traffic circle is the main traffic node of the city of Tuttlingen and between 30 TSD and 40 TSD vehicles are counted there daily, no conventional crosswalk (traffic light solution) can be provided, as this would lead to considerable traffic problems.

Therefore, in order to maintain pedestrian and bicycle traffic between the train station and the city center, a new pedestrian and bicycle underpass will be built between the Schauberweg (side of the train station) and the municipal utilities of the city of Tuttlingen. This should be bright and friendly design and take into account the special location of the company Aesculap.

The old existing underpass can not be maintained due to the new road layout (four-lane expansion of the federal roads B311 and B14 in the area of the traffic circle and bypass solutions) and will be „deconstructed“.

Design

The design envisages a three-part structure consisting of the two ramp structures and the underpass structure itself. The division of the structure (block sections and joint divisions) in the present manner is necessary due to the geometric and traffic boundary conditions.

The first 20 m will be enclosed on both sides with angle retaining walls and the further course will be designed as a trough cross-section up to the underpass portal. The wall thickness is 40 cm and will be produced in concrete grade C35/45, XD1, XC4, XF2. The walls are terminated by a cornice that runs through the entire structure as a 50 cm high belt. This provides an additional visual structure. The cornice is made of concrete and is set back 10 cm from the inside of the walls. The railings are mounted on the cornice.

The access on the east side is made by means of angled retaining walls along the staircase and the bicycle ramp is also made as a trough cross-section. The walls will have the same dimensions and articulation as on the west side. The handicapped ramp will be bordered on both sides by means of border stones, paved and will be earthworked.

The underpass structure will be constructed as a frame structure (side walls and roadway slab). Since the top edge of the roadway slab must adapt to the constantly changing longitudinal and transverse gradient of the traffic circle, this results in a variable slab height.

Towards the inner traffic circle, the underpass structure will have a circular opening with an unwinding length of approximately 20 m.

The entire structure – except for the stairway in the area of the pedestrian overpass over the west bike path ramp – will be constructed in cast-in-place concrete on falsework. The stairway structure over the west ramp will be precast.

Choice of construction materials

Reinforced concrete was chosen as the construction material

Special engineering achievement

Combining the individual requirements resulted in a complex spatial geometry that posed a challenge in both planning and execution.

For passenger and bicycle traffic, the connection of the train station and the Aesculap company to the city through this pedestrian and bicycle underpass is extremely important.

Explanatory report by Breinlinger Ingenieure Hoch- und Tiefbau GmbH for submission to the Ulrich Finsterwalder Ingenieurbaupreis 2015