Friday, May 22, 2015

Piano-Wire Fence: keeping the focus on the animal not the barrier



A piano-wire fence creates an inconspicuous and unobtrusive barrier between visitors and animals.


I recently saw a very tall example of a piano-wire fence at the Raptor Roost in the Albuquerque Zoo (ABQ Biopark). It's probably the tallest piano-wire fence I have seen in any zoo.


It's easy to see why it makes such a great barrier. The focus of my camera never picked up the fence and instead went right through to what matters: the animal.



While I was sorting out the photos for this post I had some ideas to improve the layout of the exhibit. The shape of the building could parallel the visitor's sight line - this would reverse the exhibit layout.


The way it's built the visitor looks against the back crossbeam (red arrow). On the right I show an alternate version:  the crossbeam has been moved above the visitor's sight line which keeps the view clean and is less distracting. And it makes the space higher where it matters for the animals: in the back of the exhibit where the nests and perching sites are located.

The front facade is needlessly high. Photo below: the visitors standing in front of the exhibit would have to throw their heads way back to see the beam above.

The front facade only needs to be around 15 feet tall for the crossbeam to be out of view.
15 feet would be still an impressively tall piano-wire facade and it might avoid one of the disadvantages of every piano-wire fence: the longer the wires the easier they are to bend apart, creating an escape route for animals if they challenge the barrier.



In order to keep the animals at Raptor Roost from parting the piano-wire a horizontal wire has been woven into the fence about 12' above the ground (photo above).
The animals living here aren't much of a challenge for the fence: Golden Eagle Aquila chrysaetos, American Bald Eagle Haliaeetus leucocephalus, and Andean Condor Vultur gryphus.

I also noticed the bottom girder.

This would be easy to hide, either with plants or by simply covering it in dirt and rocks as shown below.



Here's another view of the bottom girder (labeled Original).
I photo-sketched an improved version below the Original.


Here's the complete list of improvements:

1. Cover up the bottom girder by raising the earth.
2. Reduce the amount of railing posts by half; change them from metal to wood.
3. Place tree trunks in front of the frame columns.
4. Change the pavement from concrete to earth (or it could be stamped concrete, but in either case something less formal than in the original photo).

Summary: I reduced the architecture and softened the overall look with warmer tones and natural elements to make it look less urban.

Below: a photo-sketch animation comparing the original photo and my improved version.


An equally efficient way of hiding the beam is with plants. And plants can be an advantage for the animals because even a narrow planting strip might translate into less stress for the animals.
(Here's a link to a study that discusses this issue.
The study,  by Durham University with Chester Zoo, found that planting a meter-wide barrier of shrubs between the visitors' viewing platforms reduced the animals' stress-related behavior by more than half.)


For some part the girder is already hidden behind plants (this can be seen in the opening photos of the this post).
Overall I noticed what a great job the horticulture department did. Not only in this exhibit but throughout the zoo. Which isn't surprising because I was told the Biopark's Botanical Garden is in charge of the planting.
Once again this shows that a good horticulturist is best defense against an architect.


To end with the focus back on the piano wire, here's a photo from further away. The piano-wire fence doesn't even show in this photo - only the frame work does (a change link fence would stick out much more).


Here's a photo from another vantage point. The shrub and trees help to conceal and soften the framework.



Piano wire fence is easy on the eyes but demanding on the material. For it to work the wires need to be tightly wound which puts a lot of stress on the high tensile wire and all supporting parts.
But not to have the view obstructed by heavy fencing is worth the cost.
photo copyright unless otherwise noted 2015 Martin Schuchert


Bald Eagle - sketches by Laura Hamilton



2 comments:

Celeste said...

We just visited the ABQ Zoo and I was fascinated by the vertical barrier in the Bald Eagle enclosure, remarking on how it disappeared viewing the birds. I came home and immediately googled it to figure out what it was and found your design blog. The enclosure is already terrific but your improvements sound brilliant. I do hope you have brought them to the attention of the zoo admins. Nice job!

Martin said...

Thank you!