2132

12. Using the information given in the previous text match descriptions of the layers of Via Munita with letters in the following scheme.

1)Statumen: stones of a size to fill the hand.

2)Umbones or edge-stones.

3)Rubble or concrete of broken stones and lime.

4)The elliptical surface or crown of the road (media stratae eminentia) made of polygonal blocks of silex (basaltic lava) or rectangular blocks of saxum qitadratum (travertine, peperino, or other stone of the country).

5)Nucleus: bedding of fine cement made of pounded potshards and lime.

6)Native earth, levelled and, if necessary, rammed tight.

7)Raised footway, or sidewalk, on each side of the via.

13. Fill in the crossword:

1

2

4

6

7

8

11

12

Across:

3)The foundation and surface of a road.

6)Anything resembling or symbolizing a crown.

7)Rough in texture, structure, etc.; not fine.

8) A mixture of cement or lime or both with sand and water, used as a bond between bricks or stones

9) It becomes plastic when moist but hardens on heating and is used in the manufacture of bricks, cement, ceramics, etc.

10) A hard-surfaced path for pedestrians alongside and a little higher than a road.

11). To keep in an existing state.

12) A deep narrow steep-sided valley, especially one formed by the action of running water.

Down:

1) Fragments of broken stones, bricks.

2)A road made of logs laid down crosswise.

4) A narrow channel dug in the earth, usually used for drainage, irrigation, or as a boundary marker.

5) A construction material made of a mixture of cement, sand, stone, and water that hardens to a stonelike mass.

14. Complete the following table with the missing forms and then complete each sentence with the correct word. Use one form of each base and do not repeat any words.

1)Old roads used to be … with round stones.

2)He eventually gained … in the group.

3)The … is the layer of soil beneath the surface soil and overlying the bedrock.

4)The Indian Government was … with the power of sovereignty.

5)The idea of equal education was to … up the general standard.

6)A … is a narrow channel dug in the earth, usually used for drainage, irrigation, or as a boundary marker.

7)Recursive … may be converted into an iterative one using well-known methods.

8)She did it out of … for her parents.

15. Read the text and fill in the gaps with the following words and word combinations:

a trench, overdue boost, drainage, a carpet of finer, drainage highway construction, roadbed, cemented, a crown, road building, a foundation, subsoil, gravel, resurfacing.

MACADAM AND TELFORD’S SYSTEMS OF ROAD CONSTRUCTION

In 18th century England, the technology of … was getting a long … from two British engineers, Thomas Telford and John Loudon McAdam. Telford, originally a stonemason, came up with a system of … which required digging a trench, installing … of heavy rock, and then surfacing with a 6-inch layer of … . During construction, the center of the road was raised, producing … that allowed water to drain off. Telford attempted, where possible, to build roads on relatively flat grades (no more than a 1 in 30 slope) in order to reduce the number of horses needed to haul cargo. Telford’s pavement section was about 350 to 450 mm (14 to 18 inches) in depth and generally specified three layers. The bottom layer was comprised of large stones 100 mm (4 inches) wide and 75 to 180 mm (3 to 7 inches) in depth. It is this specific layer which makes the Telford design unique. On top of this were placed two layers of stones of 65 mm (2.5 inches) maximum size (about 150 to 250 mm (6 to 9 inches) total thickness) followed by a wearing course of gravel about 40 mm (1.6 inches) thick. It was estimated that this system would support a load corresponding to about 88 N/mm (500 lb per in. of width). In the course of his career, Telford built over 1,000 roads, 1,200 bridges, and numerous other structures. Although his system was faster and less expensive then the Romans’ method, it was still costly and required frequent … with gravel.

On the other hand, McAdam’s system was based on the principle that a well-drained road made of suitable material does not need the stone foundation of Telford’s system, but could be built directly on the … . First McAdam placed a closely compacted 10to 12-inch layer of stone which had been broken to an inch in diameter, and which was raised in the center to facilitate … . This was followed by … grained stone that was … by the setting of the powder, a process that was completed in stages, allowing the road’s traffic to compact each stage.

Macadam pavements introduced the use of angular aggregates. John McAdam (born 1756 and sometimes spelled “Macadam”) observed that most of the paved U.K. roads in early the 1800s were composed of rounded gravel. He knew that angular aggregate over a well-compacted subgrade would perform substantially better. He used a sloped subgrade surface to improve drainage (unlike Telford who used a flat subgrade surface) on which he placed angular aggregate (hand-broken with a maximum size of 75 mm (3 inches)) in two layers for a total depth of about 200 mm (8 inches). On top of this, the wearing

course was placed (about 50 mm thick with a maximum aggregate size of 25 mm). Macadam’s reason for the 25 mm (1 inch) maximum aggregate size was to provide a “smooth” ride for wagon wheels. Thus, the total depth of a typical Macadam pavement was about 250 mm (10 inches). Macadam was quoted as saying “no stone larger than will enter a man’s mouth should go into a road”. The largest permissible load for this type of design has been estimated to be 158 N/mm (900 lb per in. width). In 1815, Macadam was appointed “surveyorgeneral” of the Bristol roads and was then able to use his design on numerous projects. It proved successful enough that the term “macadamized” became a term for this type of pavement design and construction. The term “macadam” is also used to indicate “broken stone” pavement. By 1850, about 2,200 km (1,367 miles) of macadam type pavements were in use in the urban areas of the UK. Macadam realized that the layers of broken stone would eventually become “bound” together by fines generated by traffic. With the introduction of the rock crusher, large mounds of stone dust and screenings were generated. The increased use of these fines resulted in the more traditional dense graded base materials. The first macadam pavement in the U.S. was constructed in Maryland in 1823.

The greatest advantages to Macadam’s system were its speed and low cost, and it was generally adopted throughout Europe. However, it was the lack of a firm foundation for the … that was to prove the ultimate undoing of macadam roads with the advent of heavy motor vehicles, especially trucks. For that reason, on roads that had to support heavy loads, Telford’s system of construction became the standard.

Say what advantages and disadvantages these technologies have.

Advantages

Disadvantages

16. According to the previous text try to define which of these schemes refer to McAdam’s system of road construction or to Telford’s one. Prove your point of view.

1)

2)

17

. Read

the text and summarize the information referred to the types of pavements, their qualities, advantages and disadvantages.

BITUMINOUS BINDERS

Up through the time of Macadam pavements, bituminous binders had not been used. Although Roman roads used basic lime cements to hold their large stones together, roads of the late 1700s did not use a binder material and usually relied on aggregate interlock to provide cohesion. Bituminous binding materials and surface layers began to show up in pavements in the early 1800s.

18. Read the text and match the following statements with each paragraph.

1)In the second part of 19th century, with the advent of motorcar, interest in building long distance road increased in the USA.

2)During the 20th century a lot of federal programs were implemented to improve interstate road system.

3)Native Americans didn’t invent the wheel, so there were not roads in North America in the literal sense of the word.

4)In spite of all modern engineering technologies or road-building machinery, Romans constructed more miles of roads then Americans did in the 20th century.

5)Developing of clubs and cycling societies in the late 19th century initiated the Good Roads Movement.

ROADS IN THE USA

As European settlers migrated across the Atlantic to the U.S., they found themselves faced with an almost total lack of roads. In America there were only Indian trails, and while they were long and quite extensive, they were also very narrow, allowing only for single file passage of foot traffic. Like Incas, the natives of North America did not invent a wheel, and so did not develop roads that would accommodate wheeled vehicles. Initially, America’s early roads were no more than widened Indian trails which had been leveled and filled. The expression, “I'm stumped”, derived from this era, when vehicles were frequently hung up on tree stumps and could go no further until they’d been freed. Also, since most of these early roads ran through forests, the route was often marked by notches chopped on trees, from which evolved names like “Three Notch Road”.

Interest in building and maintaining long distance roads waned during the last half of the 19th century. As in England, this was due both to increased canal building and the growth of railroads. But the advent of the motorcar changed all that for everyone, and the advent of the motor truck changed it even more. Obviously, motorized vehicles made it possible for both people and goods to travel both more quickly and more comfortably – so long as there were adequate roads upon which they could travel. Thus the Good Roads Movement was born.

Before proceeding with motor vehicles, we have to give some credit to bicycles for bringing attention to the need for good roads, since these twowheeled vehicles enjoyed enormous popularity in the late 19th century. Many clubs and cycling societies sprang up, including the League of American Wheelmen, a national organization founded in 1880 whose members began crying out for better roads. The first definite success of the fledgling Good Roads Movement was achieved in 1891, when New Jersey became the first state to take responsibility at the state level for improving roads and formed a State Highway Department. Massachusetts followed this example in 1892, and by 1917 all the states had adopted similar programs.

U.S. Senator John H. Bankhead, of Jasper, AL, was president of the Good Roads Association, and played a key role in funding the nation’s road-building efforts. As Chairman of the Senate Committee on Post Offices and Post Roads, he introduced bills that appropriated money for the construction of post roads. In 1912, he pushed through a $500,000 appropriations that resulted in 425 miles of improved roads in 17 states. Then in 1916 Sen. Bankhead got the Federal Highway Act passed, which has been the basis for a continuing federal aid road building program ever since. These early programs led to both the Highway Trust Fund which was implemented in 1956 in order to construct our interstate highway system, and the Federal-Aid Highway Act of 1968, which modified and expanded the interstate system.

Ironically, even at its height, our modern interstate highway system totals only about 42,500 miles (as of 1991). Granted, this figure does not include surface streets or other roads. But 2,000 years ago the Romans, without the help of all our engineering technology or road-building machinery, constructed 53,000 miles of roads, much of which is still in use today.

19. Look through the text and place the parts of the text in the

following order:

1)The Rise of Portland Cement Concrete

2)The Original PCC Pavement

3)Innovations in Construction

4)Innovations in Performance

PORTLAND CEMENT CONCRETE PAVEMENT

Portland cement concrete (PCC) was essentially invented in 1824. In 1889, George W. Bartholomew proposed building the first PCC pavement in Bellefontaine, Ohio. Bartholomew was convinced that his “artificial stone” (the term “concrete” had not come into use yet) was a suitable substitute for the brick and cobblestone of the day. In order to convince the city of Bellefontaine to allow him to build his PCC pavement, Bartholomew agreed to donate all the materials and post a $5,000 bond guaranteeing the pavement’s performance for five years. In 1891, the first truly rigid pavement was mixed on site and placed in 5 ft. square forms. In order to match the performance and appearance of the standard cobblestone pavements of the day, Bartholomew scored 100 mm (4 inch) squares into the PCC surface to give better footing for horses (a practice continued to this day, although not for horses anymore). By 1914, Portland cement had been used to pave 2,348 miles of roadway.

Although Portland cement has been around since 1824 (when Joseph Aspdin, a Leeds mason took out a patent on a hydraulic cement that he coined “Portland” cement) it was not directly used in roadway pavements until the late 1800s.

In 1946, two Iowa highway engineers, James W. Johnson and Bert Myers, conceptualized the slip form paver. In 1949, the Iowa Highway Department constructed the first slipformed roadway, a 3 m (9 ft.) wide, 150 mm (6 inch) thick section of county road. By placing two lanes side-by-side, a typical 6 m (18 ft.) wide county road could be built. The paver attached to a ready mix concrete truck, which would discharge its load into the paver, then pull the paver forward. In 1955, Quad City Construction Company developed an improved, self-propelled, track-mounted slipform paver capable of placing 8 m (24 ft.) wide slabs up to 250 mm (10 inches) thick. In just a few years, several equipment manufacturers were marketing slipform pavers capable of placing concrete up to four lanes wide.

During the same period, central mixing replaced on-site mixing on most paving jobs. Evaluations by several agencies showed that central-mixed concrete

could be hauled from the mixer to the slipform paver in non-agitating dump trucks with no loss in workability or quality.

It was also during the late 1940s and early 1950s that paving contractors began experimenting with sawed concrete joints. Previously, joints were formed in the plastic concrete with jointing tools. These hand-formed joints often created a rough ride. After early attempts in Kansas and California, sawing was used on several projects in 1951, and soon became a standard construction method.

By the 1930s a number of states started using de-icing salts to remove ice and snow from pavements. About the same time, surface scaling developed on many pavements in northern climates. Research by the Portland Cement Association (PCA) and several state highway departments found that freeze and thaw cycles, accelerated by the use of de-icing salts, were causing the problem. Further research lead to the development of air entrained PCC that was largely freeze-thaw resistant.

During the 1920s and 1930s, PCC pavement was usually constructed directly on the underlying soil. This practice was satisfactory until the 1930s when highway truck traffic increased to the point where pumping distresses began to appear on roadways carrying heavy truck traffic. Research into this phenomenon resulted in recommendation of a non-pumping layer called a subbase (although now this layer is often referred to as the base layer) be placed under the PCC slabs. Gravel, crushed stone, and slag were commonly used as subbase material. In the late 1940s, California began using cement-treated granular bases under concrete pavements. This practice quickly spread to other states.

Road and pavement building has often been used as a benchmark of a civilizations advancement. The quality and strength of many of the ancient roads has helped them survive to this very day. The Via Appia in Rome is now over 2,300 years old and is still used today. As the use of slave labor declined, smaller more economical roads, such as Telford and Macadam roads, began to arise. Around the beginning of the 19th century, binding agents began to be used to assist aggregate cohesion and improve the durability of roads. By the end beginning of the 20th century, the two principal pavement types, flexible and rigid, had taken on many of their modern qualities and were being built throughout the U.S.

20. Make a general recommendation annotation on the text above.