Kelio istorija. Kelių projektavimas

Abstract

This paper deal with the Road Maps and the beginning of design of roads. The oldest known map is dated at 2200 B. C. and is of the ancient Mesopotamian city of Lagash. It is carved on the lap of the statue of the city's ruler; Gudea. The Greeks introduced the science of cartography and, consequently improved maps. The next advance came late in the first century B. C. when Marcus Agrippa, at the request of Emperor Augustus, spent twenty years mapping the Roman Empire. The master copy of his work was engraved in marble on a wall of the Forum in Rome. In the second century A.D. Cloudius Ptolemy published his influential eight-volume „Guide to Geography". The work of Agrippa and Ptolemy served as a model for the famous Roman itinerarium, which was basically a route map giving distances between stations or post houses together with other data such as road conditions, rivers, and shortcuts. Road guides in the United States began with „A Survey of the Roads of the United States of America", produced by Christopher Coles and published in 1789. The first useful modern maps were produced by the cycle clubs in the early 1880s, and Michel in began producing its famous guides in 1900. The German army subsequantly used Michel in maps to plan its successful invasion of northern France in 1914. Engineers have always been concerned with the geometric alignment of higways since the bigining of road construction. An economic alignment meant avoiding long, steep ungrades in order to reduce the moving resistance and to better utilize the pulling power of animals. Before the invention of automobile, the higways were designed for animal-drawn vehicles, which rarely exceeded a speed of at most 13 km/h. Thus, speed was not an important design factor and curves were mostly designed as simple sharp bends between two long tangents. Because of low speeds, the sight distance was also not important design criteria. Instead, the length and maneuverability of vehicles were the main considerations of horizontal alignment design. An advantage that the car and the truck brought to the road bulder was that they were far less demanding on vertical grades than were animal-drawn vehicles and could manage 13 percent grades. The minimum radii of curves for horizontal geometric design were for a long time based on the geometric dimension of long timber vehicles. Minimum curve radii gradually increased from the 50 m endorsed at the first (1908) PIARC meeting to 100 m in the early 1920s. to 150 m in the late 1920s, to today's 500 m or more. The invention and widespread use of the automobile led to consideration with respect to the safety standard of roads which were designed for horse-drawn vehicles. One of the main results of these safety-related questions was the establishment of speed as the main design factor in order to increase the safety standard of new ly designed roads. The concept of "superelevation of curves" was introduced for the first time in the State of New York in the year 1912. Generally, superelevation was applied to curves with radii smaller than 160m. The rate of superelevation depended on pavement type. For macadam surfaces, the rate was 1 in/ft, and for concrete surfaces, it was 5/8 in/ft. These fixed superelevations rates did not take speed and curvature into consideration. The common opinion at that time was that different rates of superelevation was not necessary.