IELTS Matching Headings 38

Just as railway bridges were the great structural symbols of the 19th century, highway bridges became the engineering emblems of the 20th century. The invention of the automobile created an irresistible demand for paved roads and vehicular bridges throughout the developed world. The type of bridge needed for cars and trucks, however, is fundamentally different from that needed for locomotives. Most highway bridges carry lighter loads than railway bridges do, and their roadways can be sharply curved or steeply sloping. To meet these needs, many turn-of-the-century bridge designers began working with a new building material: reinforced concrete, which has steel bars embedded in it. And the master of this new material was Swiss structural engineer, Robert Maillart. 

• Outdated methods retain popularity

•  Transport developments spark a major changeOutdated methods retain popularity

•  A celebrated achievement

Early in his career, Maillart developed a unique method for designing bridges, buildings and other concrete structures. He rejected the complex mathematical analysis of loads and stresses that was being enthusiastically adopted by most of his contemporaries. At the same time, he also eschewed the decorative approach taken by many bridge builders of his time. He resisted imitating architectural styles and adding design elements solely for ornamentation. Maillart’s method was a form of creative intuition. He had a knack for conceiving new shapes to solve classic engineering problems. And because he worked in a highly competitive field, one of his goals was economy - he won design and construction contracts because his structures were reasonably priced, often less costly than all his rivals’ proposals. 

• Different in all respects

• Early brilliance passes unrecognised

• Bridge-makers look elsewhere

Maillart’s first important bridge was built in the small Swiss town of Zuoz. The local officials had initially wanted a steel bridge to span the 30-metre wide Inn River, but Maillart argued that he could build a more elegant bridge made of reinforced concrete for about the same cost. His crucial innovation was incorporating the bridge’s arch and roadway into a form called the hollow-box arch, which would substantially reduce the bridge’s expense by minimising the amount of concrete needed.

In a conventional arch bridge the weight of the roadway is transferred by columns to the arch, which must be relatively thick. In Maillart’s design, though, the roadway and arch were connected by three vertical walls, forming two hollow boxes running under the roadway (see diagram). The big advantage of this design was that because the arch would not have to bear the load alone, it could be much thinner - as little as one-third as thick as the arch in the conventional bridge. 

• Frustration at never getting the design right

• The basis of a new design is born

• Transport developments spark a major change

His first masterpiece, however, was the 1905 Tavanasa Bridge over the Rhine river in the Swiss Alps. In this design, Maillart removed the parts of the vertical walls which were not essential because they carried no load. This produced a slender, lighter-looking form, which perfectly met the bridge’s structural requirements. But the Tavanasa Bridge gained little favourable publicity in Switzerland; on the contrary, it aroused strong aesthetic objections from public officials who were more comfortable with old-fashioned stone-faced bridges. Maillart, who had founded his own construction firm in 1902, was unable to win any more bridge projects, 

so he shifted his focus to designing buildings, water tanks and other structures made of reinforced concrete and did not resume his work on concrete bridges until the early 1920s.

• Bridge-makers look elsewhere

• Outdated methods retain popularity

•  Early brilliance passes unrecognised

His most important breakthrough during this period was the development of the deck-stiffened arch, the first example of which was the Flienglibach Bridge, built in 1923. An arch bridge is somewhat like an inverted cable. A cable curves downward when a weight is hung from it, an arch bridge curves upward to support the roadway and the compression in the arch balances the dead load of the traffic. For aesthetic reasons, Maillart wanted a thinner arch and his solution was to connect the arch to the roadway with transverse walls. 

In this way, Maillart justified making the arch as thin as he could reasonably build it. His analysis accurately predicted the behaviour of the bridge but the leading authorities of Swiss engineering would argue against his methods for the next quarter of a century.

•  Transport developments spark a major change

•  Bridge-makers look elsewhere

• Further refinements meet persistent objections

Over the next 10 years, Maillart concentrated on refining the visual appearance of the deck-stiffened arch. His best-known structure is the Salginatobel Bridge, completed in 1930. He won the competition for the contract because his design was the least expensive of the 19 submitted - the bridge and road were built for only 700,000 Swiss francs, equivalent to some $3.5 million today. Salginatobel was also Maillart’s longest span, at 90 metres and it had the most dramatic setting of all his structures, vaulting 80 metres above the ravine of the Salgina brook. In 1991 it became the first concrete bridge to be designated an international historic landmark.

•  A celebrated achievement

• Early brilliance passes unrecognised

• The basis of a new design is born

Before his death in 1940, Maillart completed other remarkable bridges and continued to refine his designs. However, architects often recognised the high quality of Maillart’s structures before his fellow engineers did and in 1947 the architectural section of the Museum of Modern Art in New York City devoted a major exhibition entirely to his works. In contrast, very few American structural engineers at that time had even heard of Maillart. In the following years, however, engineers realised that Maillart’s bridges were more than just aesthetically pleasing - they were technically unsurpassed. Maillart’s hollow-box arch became the dominant design form for medium and long- span concrete bridges in the US. In Switzerland, professors finally began to teach Maillart’s ideas, which then influenced a new generation of designers. 

•  Different in all respects

• Early brilliance passes unrecognised

• The long-term impact

Tourism in the mass form as we know it today is a distinctly twentieth-century phenomenon. Historians suggest that the advent of mass tourism began in England during the industrial revolution with the rise of the middle class and the availability of relatively inexpensive transportation. The creation of the commercial airline industry following the Second World War and the subsequent development of the jet aircraft in the 1950s signalled the rapid growth and expansion of international travel. This growth led to the development of a major new industry: tourism. In turn, international tourism became the concern of a number of world governments since it not only provided new employment opportunities but also produced a means of earning foreign exchange.

• The development of mass tourism

• The history of travel

• Travel for the wealthy

Tourism today has grown significantly in both economic and social importance. In most industrialised countries over the past few years the fastest growth has been seen in the area of services. One of the largest segments of the service industry, although largely unrecognised as an entity in some of these countries, is travel and tourism. According to the World Travel and Tourism Council (1992), travel and tourism is the largest industry in the world on virtually any economic measure including value-added capital investment, employment and tax contributions,. In 1992’ the industry’s gross output was estimated to be $3.5 trillion, over 12 per cent of all consumer spending. The travel and tourism industry is the world’s largest employer the almost 130 million jobs, or almost 7 per cent of all employees. This industry is the world’s leading industrial contributor, producing over 6 per cent of the world’s national product and accounting for capital investment in excess of $422 billion m direct indirect and personal taxes each year. Thus, tourism has a profound impact both on the world economy and, because of the educative effect of travel and the effects on employment, on society itself.

• Earning foreign exchange through tourism

• The development of mass tourism

• Economic and social significance of tourism

However, the major problems of the travel and tourism industry that have hidden, or obscured, its economic impact are the diversity and fragmentation of the industry itself. The travel industry includes: hotels, motels and other types of accommodation; restaurants and other food services; transportation services and facilities; amusements, attractions and other leisure facilities; gift shops and a large number of other enterprises. Since many of these businesses also serve local residents, the impact of spending by visitors can easily be overlooked or underestimated. In addition, Meis (1992) points out that the tourism industry involves concepts that have remained amorphous to both analysts and decision makers. Moreover, in all nations this problem has made it difficult for the industry to develop any type of reliable or credible tourism information base in order to estimate the contribution it makes to regional, national and global economies. However, the nature of this very diversity makes travel and tourism ideal vehicles for economic development in a wide variety of countries, regions or communities.

• The contribution of air travel to tourism

• Difficulty in recognising the economic effects of tourism

• The history of travel