Monster Welcomes Batbridge


The town of Monster, South Holland, The Netherlands, has a bridge built with the unique specifications of some specific residents in mind…and it’s not the townspeople.

The Vlotwatering Bridge, commissioned by the Municipality of Westland, is designed so that bats are able to roost in its many recesses.

Designed by NEXT Architects, Amsterdam, and built by Pieters Bouwtechniek, Haarlem, the structure affectionately known as “Batbridge” has been shortlisted for the ARC15 Detail Award, NEXT announced Oct. 23.

Building for Bats

The Vlotwatering Bridge crosses a river that serves as an important natural pathway for the local bat population, where the mammals congregate to catch insects along the waterway.

Of this native population, Bart Reuser, NEXT Architects co-founder, told Dezeen magazine in June: "One of the noticeable things of the area was that there were already different types of bats flying the route over the water—throughout the winter periods they hide in World War Two concrete bunkers around the area, for the moderate climate."

According to the firm, it kept these details in mind when planning the bridge design.

The group decided that the components of the bridge—the concrete structure, height of construction within the deck and its railings—could be designed not only with pedestrians and bicycles in mind, but also for a variety of native bat species.

Bat-Friendly Details

With its diverse sheltered roosting spots for the mammals, the final design is meant to provide an “ideal habitat” for a variety of different bat species so that a large colony can be supported near the bridge.

While the 25-meter (about 82-foot) concrete arch is said to contribute a “stable and pleasant climate” for bats, all of the bridge areas were built to offer roosting spots to meet different seasonal needs.

Raymond Rutting

The underside of the bridge features slits that create access points for the bats. The slits line up with the vertical slats of the wooden screen wall above.

The abutment at the north side of the structure provides a source of shelter for the winter months, when the bats will hibernate. Masonry walls within the interior cavity divide the space into smaller spaces for roosting.

Extra mass was added to the concrete in this area to help regulate temperature during these months, Dezeen reported.

"Bridges are heavy structures by themselves so with small adaptations we can make them suitable as bat places,” Reuser said. “In our case we needed to thicken the concrete foundation, walls and decks to an average of 0.75 metres [about 2.5 feet]."

Both the deck and brick balustrade include small openings that make for ideal spots for summer perches.

The underside of the bridge features 300-by-20mm (12-by-0.8-in.) slits that create access points for the bats. The slits line up with the vertical slats of the wooden screen wall above.

Along the brick wall, small openings provide access to cool spots for summer roosts, as the brick protects the animals from the heat during the summer months.

Here and in the winter roosts, the architects made sure that the openings were small enough that the bats could enter, but their predators—cats, owls, humans—could not.

A small hatch does make the area accessible to humans who monitor the bat population, Dezeen added.

Human-Friendly Details

Construction of the bridge began in March 2015 and was completed just this month (October).

According to Dezeen, although the 25-meter span serves to bridge the banks of the Vlotwatering river it crosses, the structure itself is actually 70 meters in length (about 230 feet). The seven-meter (23-foot) width delivers an efficient crossing path for pedestrians and cyclists.

The curves of the S-shaped deck, supported with a pressure arc that slants under the bridge, as ArchDaily noted, are clad with wooden slats and bricks on opposite sides, forming low walls out of the materials.

Raymond Rutting

Along the brick wall on one side of the structure, small openings provide access to cool spots for summer roosts, as the brick protects the animals from the heat during the summer months.

The wood cladding mirrors materials used elsewhere within the 21-hectare (52-acre) waterway project transforming the area into a recreation spot and wildlife habitat, of which this bridge is a part. 

Form and Function

This combination of functionality for both humans and the bat population, as well as its aesthetics, earned the Batbridge a spot in the ARC15 Detail Award competition, hosted by Dutch magazine de Architect.  

According to the competition site, the ARC15 Detail Award honors architecturally challenging projects already completed which distinguish themselves through innovative details within a coherent overall concept.

The purpose of the award is to highlight the social importance of architecture, strengthening the role of architecture in public life and encourage contacts between architects, suppliers and clients.

Batbridge seems an ideal candidate, as bat-expert Marcel Schillemans, of the Dutch Mammal Society, described the finished structure as a "textbook example of how a functional object can at the same time serve nature," Dezeen reported.

The bridge is shortlisted along with MVRDV's Markthal and Mei architects McDonalds Rotterdam.


Tagged categories: Aesthetics; Asia Pacific; Bridges; Competitions; Design; EMEA (Europe, Middle East and Africa); Environmentally friendly; Latin America; North America; Program/Project Management

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