"In Bolivia's jungles and steep cliffs the Yungas people do not walk. They fly. On ropes. Like birds. Faster than astronauts. These 'birds' are known as cocaleros, or coca harvesters. They use ropes to swing across the narrow valleys, suspended from ancient rusting pulleys." Watch the video. Jerry, thanks for the link. Previously: Aerial ropeways: automatic cargo transport for a bargain.
3 posts categorized "Bridges"
Covered Bridges: How to Build and Rebuild Them
"This manual is intended to provide comprehensive support to those involved with maintaining, assessing, strengthening, or rehabilitating covered bridges, especially heavy timber truss bridges. At one time, the United States reportedly had 14,000 of these unique bridges dotting the countryside over a surprisingly large area. Now, fewer than 900 of the historic structures survive.
Timber bridges initially were built without coverings and failed in just a few years because of rot and deterioration, because chemical wood preservatives were not available or used. Builders familiar with the construction of houses, barns, and large community structures naturally added siding and roofs to help protect the bridge. They understood that the covering would soon pay for itself. They believed that regular maintenance and occasional replacement of the light covering was far easier and cheaper than building an entirely new bridge. North American covered bridges still serve after nearly 200 years, due in part to the continued soundness of the trusses, which was possible only with these protective coverings."
"Covered Bridge Manual", 327 pages, US Department of Transportation, 2005. Via Arquitectura y madera. Previously: wooden bridges / wooden pipelines. Picture by Rainer Ebert.
Wooden Bridges
This wooden bridge (length 32 metres, width 12 metres, height 16 metres) was inaugurated on April 15th in Sneek, the Netherlands. The "Krúsrak" is the first wooden bridge in the world that can support the heaviest load class of 60 tons. Its life expectancy is 80 years. Thanks to a chemical treatment of the softwood, the bridge can withstand insects, fungi and the harsh weather conditions in the most northern province of the Netherlands (Friesland). Wooden bridges require much less energy to construct than steel or concrete bridges. Only the road-surface of the "Krúsrak" is made of steel - originally it was planned to be of wood, too, but then it should have been 2 metres thick. More information here (in English) and here (in Dutch).
Related: Covered bridges - how to build and rebuild them. Also: wooden pipelines.
