交通工程专业外文翻译外文文献英文文献.doc
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1、 2012 土木工程学院交通工程专业中英文翻译Road Design专 业:交 通 工 程英文原文The Basics of a Good RoadWe have known how to build good roads for a longtime。 Archaeologists have found ancient Egyptian roadsthat carried blocks to the pyramids in 4600 BCE。 Later,the Romans built an extensive road system, using thesame principles w
2、e use today. Some of these roads arestill in service。If you follow the basic concepts of road building, youwill create a road that will last. The ten commandmentsof 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)D
3、esign 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 records1Get water away from the road35324 89FC 觼30582 7776 睶21205 52D5 動/34600 8728 蜨6sWe cant overemphasize the importance of good drainage.Engineer
4、s estimate that at least 90 of a roadsproblems can be related to excess water or to poor waterdrainage. Too much water in any layer of a roadsstructure can weaken that layer, leading to failure.In the surface layer, water can cause cracks andpotholes。 In lower layers it undermines support, causingcr
5、acks and potholes. A common sign of water in anasphalt road surface is alligator cracking - an interconnectedpattern of cracks forming small irregular shapedpieces that look like alligator skin。 Edge cracking, frostheaves, and spring breakup of pavements also point tomoisture problems.To prevent the
6、se problems remember that water: flows downhill needs to flow someplace is a problem if it is not flowingEffective drainage systems divert, drain and dispose ofwater。 To do this they use interceptor ditches and slopes,road crowns, and ditch and culvert systems。Divert Interceptor ditches, located bet
7、ween the roadand higher ground along the road, keep the water fromreaching the roadway. These ditches must slope so theycarry water away from the road.Drain Creating a crown in the road so it is higheralong the centerline than at the edges encourages waterto flow off the road。 Typically a paved crow
8、n should be14 higher than the shoulder for each foot of width fromthe centerline to the edge。 For gravel surfaces the crownshould be 12 higher per foot of width. For this flow pathto work, the road surface must be relatively water tight.Road shoulders also must be sloped away from the roadto continu
9、e carrying the flow away。 Superelevations(banking) at the outside of curves will also help drainthe road surface.Dispose - A ditch and culvert system carries water awayfrom the road structure。 Ditches should be at least onefoot lower than the bottom of the gravel road layer thatdrains the roadway。 T
10、hey must be kept clean and mustbe sloped to move water into natural drainage。 If waterstays in the ditches it can seep back into the roadstructure and undermine its strength. Ditches should alsobe protected from erosion by planting grass, or installingrock and other erosion control measures。 Erosion
11、 candamage shoulders and ditches, clog culverts, undermineroadbeds, and contaminate nearby streams and lakes.Evaluate your ditch and culvert system twice a yearto ensure that it works。 In the fall, clean out leaves andbranches that can block flow。 In spring, check for andremove silts from plowing an
12、d any dead plantmaterialleft from the fall。2 Build on a firm foundationA road is only as good as its foundation。 A highway wearsout from the top down but falls apart from the bottom。The road base must carry the entire structure and thetraffic that uses it。To make a firm foundation you may need to st
13、abilizethe roadbed with chemical stabilizers, large stone calledbreaker run, or geotextile fabric。 When you run intoconditions where you suspect that the native soil isunstable, work with an engineer to investigate thesituation and design an appropriate solution.3 Use the best materialsWith all road
14、 materials you “pay now or pay later。”Inferior materials may require extensive maintenancethroughout the roads life. They may also force you toreplace the road prematurely.Crushed aggregate is the best material for the basecourse。 The sharp angles of thecrushed material interlockwhen they are compac
15、ted。 This supports the pavementand traffic by transmitting the load from particle toparticle。 By contrast, rounded particles act like ballI627010 6982 概30859 788B 碋kv22460 57BC 垼bearings, moving under loads。Angular particles are more stable than rounded particles。Asphalt and concrete pavement materi
16、als must be ofthe highest quality, designed for the conditions, obtainedfrom established firms, and tested to ensure it meetsspecifications.4Compact all layersIn general, the more densely a material is compacted, thestronger it is。 Compaction also shrinks or eliminates openspaces (voids) between par
17、ticles. This means that lesswater can enter the structure。 Water in soil can weakenthe structure or lead to frost heaves。 This is especiallyimportant for unsurfaced (gravel) roads. Use gravel whichhas a mix of sizes (wellgraded aggregate) so smallerparticles can fill the voids between larger ones. G
18、oodcompaction of asphalt pavement lengthens its life。5Design for traffic loadsand volumesDesign for the highest anticipated load the road will carry。A road that has been designed only for cars will not standup to trucks. One truck with 9 tons on a single rear axledoes as much damage to a road as nea
19、rly 10,000 cars.Rural roads may carry log trucks, milk trucks, firedepartment pumper trucks, or construction equipment。If you dont know what specific loads the road will carry,a good rule of thumb is to design for the largest piece ofhighway maintenance equipment that will be used onthe road。A well-
20、constructed and maintained asphalt roadshould last 20 years without major repairs or reconstruction.In designing a road, use traffic counts that projectnumbers and sizes of vehicles 20 years into the future。These are only projections, at best, but they will allowyou to plan for traffic loadings thro
21、ugh a roads life.6 Design for maintenanceWithout maintenance a road will rapidly deteriorate andfail. Design your roads so they can be easily maintained。This means: adequate ditches that can be cleaned regularly culverts that are marked for easy locating in the spring enough space for snow after it
22、is plowed off the road proper cross slopes for safety, maintenance and toavoid snow drifts roadsides that are planted or treated to prevent erosion roadsides that can be mowed safely30413 76CD 盍28180 6E14 渔PA28627 6FD3 濓27456 6B40 歀34878 883E 蠾A rule of thumb for adequate road width is to makeit wid
23、e enough for a snowplow to pass another vehiclewithout leaving the travelled way。Mark culverts with a post so they can be located easily。7 Pave only when readyIt is not necessary to pave all your roads immediately。There is nothing wrong with a wellbuilt and wellmaintainedgravel road if traffic loads
24、 and volume donot require a paved surface。 Three hundred vehicles perday is the recommended minimum to justify paving.Dont assume that laying down asphalt will fix a gravelroad that is failing. Before you pave, make sure you havean adequate crushed stone base that drains well and isproperly compacte
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