交通建设项目工程专业外文翻译外文文献英文文献

工程 土木工程学院交通工程专业土木工程学院交通工程专业 中英文翻译中英文翻译 Road Design 专专业业 交 通 工 程 英文原文 The Basics of a Good RoadThe Basics of a Good Road We have known how to build good roads for a long time. Archaeologists have found ancient Egyptian roadsthat carried blocks to the pyramids in 4600 BCE. Later,the Romans built an extensive road system, using the same principles we use today. Some of these roads are still in service. If you follow the basic concepts of road building, you will create a road that will last. The ten commandments of a good road are （1）Get water away from the road （2）Build on a firm foundation （3）Use the best materials （4）Compact all layers properly （5）Design for traffic loads and volumes （6）Design for maintenance （7）Pave only when ready （8）Build from the bottom up （9）Protect your investment （10） Keep good records 1 1．．Get water away from the roadGet water away from the road We can’t overemphasize the importance of good drainage.Engineers estimate that at least 90 of a road’s problems can be related to excess water or to poor waterdrainage. Too much water in any layer of a road’sstructure can weaken that layer, leading to failure. In the surface layer, water can cause cracks and potholes. In lower layers it undermines support, causing cracks and potholes. A common sign of water in an asphalt road surface is alligator cracking an interconnected pattern of cracks ing small irregular shaped pieces that look like alligator skin. Edge cracking, frost heaves, and spring breakup of pavements also point to moisture problems. To prevent these problems remember that water flows downhill needs to flow someplace is a problem if it is not flowing Effective drainage systems divert, drain and dispose of water. To do this they use interceptor ditches and slopes,road crowns, and ditch and culvert systems. DivertDivert Interceptor ditches, located between the road and higher ground along the road, keep the water from reaching the roadway. These ditches must slope so they carry water away from the road. DrainDrain Creating a crown in the road so it is higher along the centerline than at the edges encourages water to flow off the road. Typically a paved crown should be 1⁄4“ higher than the shoulder for each foot of width from the centerline to the edge. For gravel surfaces the crown should be 1⁄2“ higher per foot of width. For this flow path to work, the road surface must be relatively 工程 water tight. Road shoulders also must be sloped away from the road to continue carrying the flow away. Superelevations banking at the outside of curves will also help drain the road surface. DisposeDispose A ditch and culvert system carries water away from the road structure. Ditches should be at least one foot lower than the bottom of the gravel road layer that drains the roadway. They must be kept clean and must be sloped to move water into natural drainage. If water stays in the ditches it can seep back into the road structure and undermine its strength. Di