Colombia: New Bridge over the Magdalena River - XVII Structural Engineering Journals

[proyejam]

New Bridge over the Magdalena River in Colombia, South America

Jairo Arana María, Civil Engineer, B.S.C.E., M.S.C.E., University of California, Berkeley

XVII Structural Engineering and V Structural Steel Journals – Colombian Society of Engineers – June 8, 2007


New Bridge “Pumarejo” over the Magdalena River

1. History
The Transportation Minister, through the Engineering Society of Atlántico, presented a contest to Architectural and Civil Engineering Professionals, for a preliminary design to make movable the Bridge “Laureano Gomez” (Pumarejo) to allow the passage of larger vessels under the bridge over the Magdalena River in Barranquilla, Colombia.

2. General Features of the existing Bridge
The “Laureano Gomez” Bridge, built during 1972-1974, has a total length of 1499 meters and is located 24 kilometers from the end of the Magdalena River. The bridge is reinforced and prestressed concrete, with a main span of 140 meters cable-stayed type bridge.

2.1 Elevation and clearance under the Bridge
The main 140 meters span over the navigable canal on the west side of the river, is composed of prestressed segmental box sections, supported by cables that extend 48.00 m to the 69.50 m adjacent spans, to balance the dead load of the bridge. The vertical clearance in the main span varies from 14 to 16 m between the two supports towers located on the navigable canal on the west side of the river.

2.2 Typical section of the existing Bridge
The structure has a roadway width of 8.00 m and two 2.25 m sidewalks for a total width of 12.50 m. There are a total of 28 bents of which 25 have a 47.00 m span. The typical 47.00 m span consists of three prestressed concrete beams simply supported at each bent. The bridge deck is precast concrete joined in site with the prestressed concrete beams for a composite behavior for better resistance and stiffness.

2.3 Cross-section through the main span
The main central towers serve as support to a concrete box type structure built by 6.00 m segmental cantilever construction sections. On each side of the main towers, the concrete box girder is supported by four cables, forming a continuous rigid beam on flexible supports.

Purpose of this report
The present report was the winner of the contest with the alternatives to make movable the Bridge “Laureano Gomez” (Pumarejo) or replace it with a new bridge, considering the conditions and behavior of the existing structure.

3. First Alternantive
The first alternative is to construct a bascule bridge between the main two towers, axis 20 and 21, with a 140 m span, which has the highest vertical clearance located at the navigable canal in the west side of the river.
The initial construction was made by segmental precast concrete sections that were installed successively with temporary support cables. Several segmental sections can be demolished at the construction joints to build the bascule bridge.
To lift the movable bascule bridge, cables can be installed at the main towers, anchored at the adjacent support, axis 19 and 22, on each side.
By dividing the continuous rigid beam between the main span, the box beam will not act as initially designed to resist the live and dead load moments with negative and positive moments giving the structure more resistance and distribution of stresses.
Laterally, the structure will be supported on one side only, producing moments and torsion. The lateral resistance against wind and earthquake loads will not be as effective as the actual 140 m span which is supported on both sides at the main towers.

Conclusion:
• The bascule bridge is not recommendable.
• Traffic will be interrupted during construction.

4. Second Alternative
To avoid affecting the main span, the bascule bridge can be constructed between axis 5 and 6, located at the east side of the river which has an approximated width of 400 m. Since the depth of the river on the east side of the river is 6.00 m compared to the navigable canal on the west side which is 10.00 m deep, dredging of the river must be done to obtain sufficient depth.
To avoid traffic interruption during construction, a parallel bridge can be built and joined at the ends with the existing bridge, reducing the time of closing of the bridge. The final location and dimensions of the bascule bridge will be proportioned according to the size and requirements of navigational vessels.

Conclusion:
• The bascule bridge is possible.
• Traffic is not interrupted during construction.
Disadvantages:
• Dredging must be preformed to provide sufficient depth.
• High cost of maintenance and operation.
• Aesthetics of the existing bridge.
• Number of the two existing traffic lanes will not be increased.
• It is a short term solution.

5. New Bridge “Pumaejo” over the Magdalena River
To comply with all the requirements, a new bridge with a larger vertical clearance and four traffic lanes is recommended.

Location of the new Bridge
• The proposed location is ideal due to the existing approach road not only for economical reasons but also because they are strategically located.
• The widening of the Circunvalar Avenue is being constructed. This widening consists of three lanes in each direction, a 7.00 m median, sidewalks and 7.00 m service roads on each side of the avenue.
• The Circunvalar Avenue is the most important access to the city of Barranquilla, connecting with all the roads to the interior of the country, and together with the Street 30 (Calle30) and Avenue 40 (Vía 40), form a ring around the city giving access to all the river and sea ports in Barranquilla.

Specifications and advantages of building a new Bridge
1. Vertical clearance of 35.00 to 40.00 m or greater.
2. Cross section: Four lanes minimum (two each way).
3. Two motorcycle lanes 2.40 or 3.00 m wide which can be converted in two additional lanes.
4. Pedestrian sidewalk (2.25 m).
5. Location: Parallel on the north side of the existing bridge.
6. Reinforced and prestressed concrete construction is ideal for the harsh weather in the coast.
7. Precast segmental construction is the ideal system for a bridge of this magnitude.
8. Advantage of the existing approach roads.
9. Bridge type: Cable Stayed.
10. The existing Bridge “Laureano Gómez” (Pumarejo) is an important icon of the north coast of Colombia and the city of Barranquilla, which will be replaced by a similar bridge with more greatness and aesthetics.

New Cable Stayed Bridge “Pumarejo” over the Magdalena River

[Scruffy]

the bridge looks cool but im still a little unsure of where it is. how far is this from Barranquilla and its crossing of the river?

[proyejam]

For location of bridge in Colombia, South America, use Google Earth and search for "BARRANQUILLA PUENTE PUMAREJO".

[Scruffy]

oh i get it. they are retrofitting the existing bridge. i thought this would be a completely new span. i know the old bridge. my cousin bungee jumped off it. its a cool looking bridge but this would absolutely be an improvement