土木工程桥梁方向毕业设计外文及翻译

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专业：土木工程（桥梁方向）

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2010 年 3 月

What is traffic engineering

Traffic engineering is still a relatively new discipline within the overall bounds of civil engineering. it has nevertheless already been partially planning. the disciplines are not synonymous though. transportation planning is concerned with the planning, functional design, operation and management of facilities for any mode of transportation in order to provide for the safe, rapid, comfortable, convenient, economical and enviromenally-comparible movement of people and goods. within that broad scope, traffic engineering deals with those functions in respect of roads, road networks, terminal points , about lands and their relationships with other modes of transportation.

Those definitions, based on the 1976 ones of the U.S.institute of transportation engineers are complete than, the British instituting of civil engineering which deals with traffic planning and design of roads, of frontage development and of parking facilities and with the control of traffic to provide safe, convenient and economical movement of vehicles and pedestrians.

The definitions of the disicipline are becoming clearer: the methodology is developing continuously and becoming increasingly scientific. the early rule-of-thumb techniques are disappearing.

Traffic problem

The discipline is young: the problem is large and still growing. in 1920 the total number of motor vehicles, licensed in great Britain was,650,000.fifty year later the comparable figure was 14,950,000-a growth factor of 23 times. in recent years the rate of growth has slackened somewhat, but it is still considerable: 1955 6,466,000

1960 9,439,000

1965 12,938,000

1970 14,950,000

1974 17,247,000

In order to see the problem in every day terms ,consider high street. anywhere. assuming that present trends continue, it is expected that within the next fifteen years of so the traffic on this road will increase by around forty to fifty persent. if this increased volume of traffic were to be accommodated at the

same standard as today, the road might need to be widened by a similar forty to fifty percent-perhaps extra lane of traffic for the pedestrian to cross. In man cases, to accommodate the foreseeable future demand would destroy the character of the whole urban environment, and is clearly unacceptable.

the traffic problem is of world-wide concern, but different countries are obviously at different stages in the traffic escalation-with America in the lead, while a county has few roads and a relatively low problem, as soon as the country is opened up by a road system, the standard of living and the demand for motor transport both rise, gathering momentum rapidly. eventually-and the stage at which this happens is open to considerable debate-the demand for cars, buses and lorries become satiated. the stage is known as saturation level.

For comparison ,car ownership figures in different countries in 1970 were: India 0.01 cars/person

Israel 0.05cars/person

Japan 0.09 cars/person

Ireland 0.13 cars/person

Netherlands 0.20 cars/person

Great Britain 0.21 cars/person

West Germany 0.23 cars/person

Australia 0.31 cars/person

USA 0.44 cars/person

But the growth in vehicle ownership is only part of the overall traffic problem. obviously,if a country has unlimited roads of extreme width, the traffic problem would not rise. no country in the world could meet this requirement: apart from anything else, it would not make economic for each vehicle using the roads. This figure is decreasing steadily.

Three possible solutions

The basic problem of traffic is therefore simple-an ever-increasing number of vehicles seeking to use too little roade space. the solution to the problem-is else a not-too-difficult choice from three possiblilities:

build, sufficient roads of sufficient size to cope with the demand.