• Location: A-44 Motorway in Dúrcal (Granada) SEE MAP
• Scope of Works: Detailed design
• Structural type: Fixed deck arch bridge
• Construction process: Conventional falsework
• Overall length: 55,0 m
• Spans: 55,0 m
• Deck width: 9,0 m
• Deck maximum height: 12,0 m

When a trench is cut for a roadway, on many occasions an overpass is needed to communicate the two sides. This is usually a problem, because no space is provided for the lateral spans of a three or four span bridge. Under such circumstances, a deck arch bridge is a very appropriate solution.

This was the case for the A-44 motorway in the Alhendín – Durcal section. No singular or expensive solutions were suitable for the overpass. On the contrary, smart and modest solutions were preferred. A very competitive solution is an arch bridge, when it can be built using conventional falsework directly supported on the ground.

The arch is 55,0 m long and has a 5,5 m rise, so span-to-rise ratio is 1/10. The arch supports a 9,0 m wide road.

The arch structure stands out because of its remarkable slenderness. The depth of the arch varies from 0,60m at the abutments to 0,35 m at crown. The depth of the deck is 0,35 m. The arch foundations are 4,0×3,0x8,0 m. These small foundations are possible due to the reduced weight of the structure.

The arch is fixed at its abutments. There are very important negative bending moments on these sections, so a large amount of reinforcement was needed. However, reinforcement is minimum in the other sections.

The cross section of the arch is rectangular, with variable depth and 5 m width. The spandrel columns also have a rectangular section. The deck is supported by these spandrel columns, using neoprene bearings, in order to reduce bending moments on these columns. The deck is a reinforced concrete slab, 0,35 m deep. There are two transverse cantilevers, where the steel barrier is installed.

The bridge is built using conventional falsework, supported on the ground. The construction starts before excavating the highway, in order to reduce the height of the falsework. When the arch and spandrel columns are finished, the falsework is then supported by the arch itself, and the deck is built.