Posts Tagged ‘low-tech’
Source: Low-Tech Magazine
Image from Kris de Decker
From “How to downsize a transport network: the Chinese wheelbarrow” by Kris de Decker:
For being such a seemingly ordinary vehicle, the wheelbarrow has a surprisingly exciting history. This is especially true in the East, where it became a universal means of transportation for both passengers and goods, even over long distances.
The Chinese wheelbarrow – which was driven by human labour, beasts of burden and wind power – was of a different design than its European counterpart. By placing a large wheel in the middle of the vehicle instead of a smaller wheel in front, one could easily carry three to six times as much weight than if using a European wheelbarrow.
The one-wheeled vehicle appeared around the time the extensive Ancient Chinese road infrastructure began to disintegrate. Instead of holding on to carts, wagons and wide paved roads, the Chinese turned their focus to a much more easily maintainable network of narrow paths designed for wheelbarrows. The Europeans, faced with similar problems at the time, did not adapt and subsequently lost the option of smooth land transportation for almost one thousand years.
Transport options over land
Before the arrival of the steam engine, people have always preferred to move cargo over water instead of over land, because it takes much less effort to do so. But whenever this was not possible, there remained essentially three options for transporting goods: carrying them (using aids like a yoke, or none at all), tying them to pack animals (donkeys, mules, horses, camels, goats), or loading them onto a wheeled cart or wagon (which could be pulled by humans or animals).
Carrying stuff was the easiest way to go; there was no need to build roads or vehicles, nor to feed animals. But humans can carry no more than 25 to 40 kg over long distances, which made this a labour-intensive method if many goods had to be transported. Pack animals can take about 50 to 150 kg, but they have to be fed, are slightly more demanding than people in terms of terrain, and they can be stubborn. Pack animals also require one or more people to guide them.
When carrying goods – whether by person or by pack animals – the load is not only moved in the desired direction but it also undergoes an up and down movement with every step. This is a significant waste of energy, especially when transporting heavy goods over long distances. Dragging stuff does not have this drawback, but in that case you have friction to fight. Pulling a wheeled vehicle is therefore the most energy-efficient choice, because the cargo only undergoes a horizontal motion and friction is largely overcome by the wheels. Wheeled carts and wagons, whether powered by animals or people, can take more weight for the same energy input, but this advantage comes at a price; you need to build fairly smooth and level roads, and you need to build a vehicle. If the vehicle is drawn by an animal, the animal needs to be fed.
When all these factors are taken into consideration, the wheelbarrow could be considered the most efficient transport option over land, prior to the Industrial Revolution. It could take a load similar to that of a pack animal, yet it was powered by human labour and not prone to disobedience.
Compared to a two-wheeled cart or a four-wheeled wagon, a wheelbarrow was much cheaper to build because wheel construction was a labour-intensive job. Although the wheelbarrow required a road, a very narrow path (about as wide as the wheel) sufficed, and it could be bumpy. The two handles gave an intimacy of control that made the wheelbarrow very manoeuvrable.
When the wheelbarrow finally caught on in Europe, it was used for short distance cargo transport only, notably in construction, mining and agriculture. It was not a road vehicle. In the East, however, the wheelbarrow was also applied to medium and long distance travel, carrying both cargo and passengers. This use – which had no Western counterpart – was only possible because of a difference in the design of the Chinese vehicle. The Western wheelbarrow was very ill-adapted to carry heavy weights over longer distances, whereas the Chinese design excelled at it.
On the European wheelbarrow the wheel was (and is) invariably placed at the furthest forward end of the barrow, so that the weight of the burden is equally distributed between the wheel and the man pushing it. In fact, the wheel substitutes for the front man of the handbarrow or stretcher, the carrying tool that was replaced by the wheelbarrow.
Superior Chinese design
In the characteristic Chinese design a much larger wheel was (and is) placed in the middle of the wheelbarrow, so that it takes the full weight of the burden with the human operator only guiding the vehicle. In fact, in this design the wheel substitutes for a pack animal. In other words, when the load is 100 kg, the operator of a European wheelbarrow carries a load of 50 kg while the operator of a Chinese wheelbarrow carries nothing. He (or she) only has to push or pull, and steer.
The decay of the Chinese road infrastructure
The importance of the Chinese wheelbarrow can only be understood in the context of the Chinese transportation network. Prior to the third century AD, China had an extensive and well-maintained road network suited for animal powered carts and wagons. It was only surpassed in length by the Ancient Roman road network. The Chinese road infrastructure attained a total length of about 25,000 miles (40,000 km), compared to almost 50,000 miles (80,000 km) for the Roman system.
The Chinese and Roman road systems were built (independently) over the course of five centuries during the same period in history. Curiously, due to (unrelated) political reasons, both systems also started to disintegrate side by side from the third century AD onwards, and herein lies the explanation for the success of the Chinese wheelbarrow. As we have seen, the one-wheeled vehicle appeared during this period, and this is no coincidence. Increasingly, it was the only vehicle that could be operated on the deteriorating road network.
Lessons for the future
Of course, it was not only the wheelbarrow that kept Chinese communication running after the second century AD. At least as important was the impressive network of artificial canals that complemented it. This infrastructure became ever more important after the detoriation of the road network. For example, the Grand Canal, which ran from Hangzhou to Bejing over a distance of 1800 km, was completed in 1327 after 700 years of digging.
In Europe, the first (relatively modest) canals were only built during the 16th century, and most of them only appeared in the eighteenth and nineteenth centuries. The Chinese wheelbarrow alone could not have given Europe an equally effective transport infrastructure as the Chinese, but there is no doubt that it could have made life in medieval Europe a great deal easier.
The story of the Chinese wheelbarrow also teaches us an obvious lesson for the future. While many of us today are not even prepared to change their limousine for a small car, let alone their automobile for a bicycle, we forget that neither one of these vehicles can function without suited roads. Building and maintaining roads is very hard work, and history shows that it is far from evident to keep up with it.
In this regard, it is important to keep in mind that we won’t be as lucky as the medieval Europeans who inherited one of the best and most durable road networks in the world. Our road infrastructure – mostly based on asphalt – is more similar to that of the Ancient Chinese and will disintegrate at a much faster rate if we lose our ability to maintain it. The Chinese wheelbarrow – and with it many other forgotten low-tech transportation options – might one day come in very handy again.
Read the full article (there’s a lot more, with pictures too) by Kris de Decker on Low-Tech Magazine.
From “The Sustainable Urban Dwelling Unit (SUDU)” on No Tech Magazine:
The ‘Sustainable Urban Dwelling Unit’ (SUDU) in Ethiopia demonstrates that it is possible to construct multi-storey buildings using only soil and stone. By combining timbrel vaults and compressed earth blocks, there is no need for steel, reinforced concrete or even wood to support floors, ceilings and roofs. The SUDU could be a game-changer for African cities, where population grows fast and building materials are scarce.
In “Tiles as a substitute for steel“, we highlighted the medieval art of the medieval timbrel vault, which allowed for structures that today no architect would dare to build without steel reinforcements. The technique is cheap, fast, ecological and durable. Shortly after the article was published in 2008, the timbrel vault made a comeback with two rather spectacular buildings: Richard Hawkes’ Crossway Passive House in England, and Peter Rich’s Mapungubwe Interpretation Centre in South Africa.
The cardboard formwork technique described last week promises to bring even more dramatic architecture, but at least as interesting is the news that the catalan vault is now also applied to a much more modest form of housing: the Sustainable Urban Dwelling Unit (SUDU), a low-cost family dwelling built in Ethiopia.
Though less spectacular at first sight, it could form the proof that even megacities can be constructed without the use of steel, concrete or wood.
The double-story building, which was completed in last summer, is entirely made from soil and presents an economical and ecological solution to many of Africa’s most urgent problems. The SUDU stands in Addis Ababa, Ethiopia, a country with a population of more than 80 million (growing at an average 7 percent per year). The building is a joint project of the Swiss Federal Institute of Technology (ETH Zurich) and the Ethiopian Institute of Architecture, Building Construction and City Development (EiABC).
The SUDU combines past technologies from different continents, resulting in a new approach to low-tech construction adapted to specific local conditions. In the Mediterranean region, where the timbrel vault originated, the tiles have traditionally been made from fired clay. In the SUDU, the construction technique is united with the African tradition of cement-stabilized, soil-pressed bricks, which use locally available soil. This technique is called compressed earth block (CEB) construction. The SUDU has been built largely following the same techniques used for the Mapungubwe Centre in South Africa.
Read the full article to find out more about resource pressures and engineering details.
Posted in Models by Kate Archdeacon on November 3rd, 2011
Photo: Roots of Health
From “Working With the Community to Foster Deep Roots of Health” by Molly Theobald:
Roots of Health, an organization based on the island of Palawan in the Philippines, views maternal and reproductive health as concerns that impact the well-being of entire communities.[…]
Roots of Health and its staff of young nurses and teachers, work directly with mothers and children, to bring reproductive and maternal health, nutrition, and education into the community.[…]
Roots of Health is also providing families with the tools they need to improve their nutrition.
One of these tools is a vertical garden—a large plastic drum with 40 holes cut evenly around the sides. These holes create an area for planting that is more than six times greater than the top surface of the container. The drum is filled with compost-enriched soil and planted with seeds such as eggplant, chili, pumpkin, okra and various indigenous leafy greens such as alugbati and pechay. Straw is used on the top surface as a mulch to help the soil retain moisture and nutrients.
The soil used in the vertical gardens is a homemade mixture of soil, charcoal, which acts as a conditioner, limestone, to reduce the acidity, and compost, to add additional nutrients to the soil. In this way, the vertical garden is its own self-contained and fertile growing space, producing healthy and nutrient rich harvests that are isolated from ground pollutants and pests.The organization prefers to use the plastic drums because the plastic stands up best in the humid, tropical weather, explained Marcus Swanepoel, Media and Program Manager for Roots of Health.
The drums cost approximately $15 USD each and the organization provides them to families in exchange for a small deposit. The vegetables grown in these vertical gardens not only help to improve nutrition for mothers and their children, they are also helping to diversify the diets of the entire community. Each drum produces enough food to supplement household diets, with surplus left over to be sold within the community. And households have really made the vertical gardens their own, adds Marcus. “I know some families that have set up poles on the top of the drums in order to grow beans—that isn’t something we taught them to do. They are doing it all on their own.”[…]
Read the full article by Molly Theobald, or visit the Roots of Health website.