1. Task definition

In the course of the new construction of the A 33 motorway between Osnabrück and Bielefeld, the route runs in the area of the town of Dissen and the municipality of Rothenfelde at a short distance from inhabited areas.

To protect the adjacent residential areas from noise pollution, a tunnel with a partially open top and a sound-absorbing and translucent ceiling construction was built over a length of 500 meters. The entrance sections with lengths of 76.0 m and 124.0 m were designed as open trough sections.

In this area, the route of the BAB runs in a clothoid with A = 1,000 m followed by an arc of a circle R = 2,000 m. The roadway is designed as an open trough. In the northbound direction (Osnabrück), the widening of the carriageway for the Erpen exit begins at km 85+082.92.

In the area of the trough, the gradient runs in a trough with a radius of curvature of H^ = 18,000 m. The subsequent gradient slopes R = 2,000 m. The subsequent gradients are 1.395 % and 1.077 %, respectively. In the southern trough area, the rounding of the following crest with H = 21,500 m already begins.

The cross-section corresponds to a standard cross-section in Tunnel 26Tr with lanes of 2 x 3.75 m and a hard shoulder of 1.50 m. The outer and inner walls of the trough are of the same width. Emergency walkways of 1.0 m width are provided towards the outer and inner walls. The clear width of one direction of travel is thus 11.0 m, the clear height 4.70 m.

Several traffic routes and watercourses are to be crossed in the watercourses have to be crossed or underpassed:

• the rerouted course of the "NollerGraben" stream,
• the single-track railroad line Osnabrück
• Brackwede,
• the local connection road "Bahnhofstraße",
• a DN 800 municipal storm water drain.

Furthermore, parallel to the noise protection tunnel, the relocation of the connecting road L 94/B 68 in a trough structure of 170m length became necessary.

2. Construction design

The objective of the design work was to design a noise protection tunnel that could be manufactured economically and also maintained cost-effectively during subsequent operation.

Economical production was achieved by keeping the outer cross-section contour constant and by using a standard block length. This allowed the use of the formwork sets to be optimized and a regular working cycle to be achieved. The noise protection tunnel in Dissen was divided into five large construction sections, allowing repeated use of sheet pile shoring.

Measures to maintain the noise protection tunnel in operation were minimized. The partially open ceiling construction, which is permeable to light throughout, and the arrangement of glass gable roofs in the adaptation sections made it possible to dispense with artificial lighting. Ventilation and emergency call facilities are also not required. The minimum electrical equipment to be maintained is the drainage pumping station and safety lighting in the tunnel area at 50 m intervals. If the expected self-cleaning of the glass roof surfaces is not sufficient, occasional manual cleaning of these glass surfaces will be required as a maintenance expense.

The integration of the structure into the natural environment is achieved by a continuous planted embankment, which was filled up to 1.50 m below the top of the trough wall on the outside.

In addition, there is a planted trough, generally 6.30 m wide, which is integrated into the pavement structure above each directional carriageway. In the area of the Bahnhofstrasse crossing, the full width of the tunnel deck is planted, giving it the character of a landscape bridge.

The structure is not perceived as a traffic structure of this size from a distance and when crossing in the course of Bahnhofstraße. The open trough walls receive a brick cladding for acoustic reasons.

The arrangement and sequence of layers were chosen design and driving-dynamic-psychological aspects.

In the upper area of the trough walls, a 1.50 m high, projecting masonry band is arranged. The bearing joints run parallel to the respective upper edge of the wall. Below this, the bricks are laid flush with the trough wall surface in bearing joints running parallel to the gradient. The tunnel portals are provided with a plant trough convexly rounded on the underside over the entire width.

2.1 Noise protection tunnel

The structure was designed as a massive heavyweight trough made of waterproof concrete. The thickness of the trough base resulted from the verification of the uplift safety at 1.20 m thickness. The wall thickness is 80 cm.

The structure was divided longitudinally into 12 m blocks so that shrinkage shortening remained low and, with two exceptions, no predetermined crack joints were required in the rising trough walls. The block joints were arranged perpendicular to the grade. In the block joints, three shear cams were arranged in the invert for interlocking between the blocks. The cams are 30 cm high and 20 cm deep.

The special sound-absorbing ceiling, which has sound-absorbing openings running through it over the side strips, has the task of directing as much natural light as possible onto the carriageway in order to save on lighting costs, to ensure a natural exchange of air and to reduce the sound as it emerges in such a way that the surrounding area is disturbed as little as possible.

The main load-bearing elements of the slab are 50 cm wide and 75 cm high precast reinforced concrete girders that span across the walls, where they rest on wall brackets via unreinforced elastomeric bearings.

The precast girders are 11 m long and are spaced 4 m apart. They support the so-called plant trough, which in cross-section consists of two lateral 75 cm high concrete upstands with an outer sloping approach and the 20 cm thick in-situ concrete slab in between. The concrete slab also serves as the top chord of the beams in the central area.

Between the upstands and the walls, the two lateral longitudinal lighting and ventilation openings are formed.

In each continuous section, the plant trough is provided with two centrally arranged drains, each of which drains the ceiling via a transverse drainage pipe.

In the two entrance and transition areas, roof-shaped glazing, approx. 3-6 m wide, is arranged centrally along each 150 m length for lighting reasons. The 45° inclined glazing consists of laminated safety glass panes, each of which is made up of two toughened safety glass panes, the lower pane being partially toughened and frosted with up to 40% translucency. The supporting steel structure is galvanized and coated and is fastened to the concrete structure with composite anchors.

2.2 Noise control measures

In order to prevent traffic noise from leaving the tunnel interior unabated through the longitudinal openings, these are designed to be sound-insulated. The tunnel walls and the outer sides of the upstands are clad at a height of 70 cm with highly absorbent mineral wool-filled perforated aluminum panels coated in white. In each of the openings, five plate-shaped 10 cm thick and 66 cm high sound-absorbing lamellas are inserted at an angle of 70°.

The sound-absorbing lamellas consist of highly absorbent, white-coated aluminum perforated sheet cassettes filled with mineral wool, which usually span over 4 m and are fixed there in the steel profiles on the precast concrete girders with stainless steel profiles. The steel profiles for the supports of the lamellas are hot-dip galvanized and coated.

2.3 Open trough sections

A 76 m long trough section adjoins the northern tunnel end and a 124 m long trough section adjoins the southern tunnel end. In the northern trough section, the height of the top edge of the eastern outer wall is reduced by about 1.30 m compared to the tunnel cross-section, so that the absolute height of the wall is reduced from 6.38 m to 4.02 m as a result of the additional gradient rise.

The thickness at the wall head is kept constant at d = 35 cm for design and production reasons, so that the wall inclination against the vertical changes steadily from 7.1% to 10.2%. The western outer wall is only designed at the structurally required height of 30 cm above the design water level or above the top of the sidewalk.

In the southern trough area, the two upper edges of the trough walls are guided horizontally, so that the absolute wall height is only reduced from 6.38 m to 5.19 m due to the rise in the gradient.

2.4 Overpass of Bahnhofstrasse

The Bahnhofstrasse overpass is integrated into the tunnel structure.

The slab is solid with a thickness of 80 cm and connected to the frame walls in a flexurally rigid manner. The spans are 2 x 11.80 m. The ratio of span to construction height is l-/h 15, so that prestressing could be dispensed with.

The Bahnhofstrasse widens in the trough area from a carriageway width of approx. 7 m to approx. 9 m.

2.5 Overpass of the DB line

At km 85+038, the A 33 motorway crosses the existing single-track railroad line. Due to the inclined crossing (crossing angle 51.8 gon) and the low available construction height, a simple trough cross-section was chosen as a continuous system. The design height of the longitudinal girders is 1.50 m, resulting in a moderate slenderness of 27/1.5 = 18 for a maximum span of 27.0 m. A closed deck plate was placed between the longitudinal girders, which also forms the top chord of the cross girders and the longitudinal ribs under the rails.

2.6 Waterproofing

The structure was constructed throughout in B 25 waterproof concrete in accordance with the conditions for B 11 concrete. Waterproofing against water pressing from the outside was provided in the block joints by internal elastomeric waterstops. Joint waterstops with a central hose were selected to absorb movements. To ensure a high degree of protection against water circulation, only waterstops with vulcanized sheet metal strips were used.

The block joints were given a 2 cm thick hydrophobic joint insert made of rigid foam. The top and bottom sides of the shear studs were given a coating of sliding sheeting, and the end faces were given a bituminous coating. All construction joints were sealed by internal sheet metal strips. The width is at least 250 mm, the sheet thickness at least 1 mm. The joints with the expansion joint strips were welded watertight.

The waterproofing of the carriageway was carried out in accordance with Richtz. Dicht 3. The pavement was laid on a sealing and single-layer sealing layer of bituminous welded sheeting.

The pavement was laid to a total thickness of 12 cm in accordance with the "Preliminary Recommendations for the Production of Concrete Pavements on Troughs and Tunnels" with

• 4.0 cm wearing course of stone mastic asphalt,
• 4.0 cm intermediate layer of Stone Mastic Asphalt,
• 3.5 cm protective layer of mastic asphalt,
• single-layer bituminous welding membrane,
• sealing

installed.

3. Construction phase

Construction began in January 1997 with the construction of the excavation shoring for the third section. After completion of the dewatering and excavation work in this section, the concrete bases and outer walls were then constructed in this section. After backfilling the work area, the sheet piles of the 3rd construction section were pulled and reinstalled in the 2nd construction section. After completion of the 2nd construction section, the long sheet piles were then pulled again and reinstalled in the 4th construction section. Work on the 1st and 5th construction phases (short sheet piles) ran in parallel.

 

 

• Country: Germany
• Region: Lower Saxony
• Tunnel utilization: Traffic
• Type of utilization: Road tunnel
• Client: Bundesrepublik Deutschland
• Consulting Engineer: Lindschulte + Partner
• Contractor: Gebr. Echterhoff GmbH & Co. KG, Philipp Holzmann AG, Heinrich Diekmann GmbH & Co. KG
• Main construction method: Open
• Type of excavation: Excavator
• No. of tubes: 1
• Tunnel total length: 700 m
• Cross-section: 51.70 m²
• Contract Volume: 56 mill. DM
• Construction start/end: 01/97 till 05/99