道路工程畢業(yè)設(shè)計外文翻譯---高速公路設(shè)計與施工

1、<p><b>　　原文</b></p><p>　　Highway Design and Construction: The Innovation Challenge Author: Robert E. Skinner Jr.</p><p>　　Innovations and advances in research are changing the w

2、ay highways are built in America.</p><p>　　The Egyptians were pouring concrete in 2500 BC, and the Romans used it to construct the Pantheon and the Colosseum. By the mid-1800s, Europeans were building bridge

3、s with concrete, and the first “modern” concrete highway pavements appeared in the latter part of the 19th century. Naturally occurring asphalts, which have been used for waterproofing for thousands of years, came into c

4、ommon use in road construction in the 1800s. The first iron bridge was constructed in 1774, but by the end of the 19</p><p>　　Everyone is familiar with concrete, asphalt, and steel, and some of us have worke

5、d with them, perhaps on home improvement projects. This familiarity, coupled with the long history of their many uses, has led many otherwise technically savvy people to believe that these materials are well understood,

6、that their performance can be easily and reliably predicted, and that the technical challenges in using them for highways were overcome long ago. However, such notions are largely incorrect and misle</p><p>

7、　　For example, consider concrete, which is a mixture of portland cement, sand, aggregate (gravel or crushed stone), and water. Its performance characteristics are determined by the proportions and characteristics of the

8、components, as well as by how it is mixed and formed. The underlying chemical reactions of concrete are surprisingly complex, not completely understood, and vary with the type of stone. Steel may be added for tensile str

9、ength (reinforced concrete), and a variety of additives have b</p><p>　　_________________________Many factors contribute to theurgent need for innovation inhighway construction._________________________&

10、lt;/p><p>　　Concrete is the most heavily used substance in the world after water (Sedgwick, 1991). Worldwide, concrete construction annually consumes about 1.6 billion tons of cement, 10 billion tons of sand an

11、d crushed stone, and 1 billion tons of water (M.S. Kahn, 2007). Given transportation costs, there is a huge financial incentive to using local sources of stone, even if the properties of that stone are less than idea

12、l. Thus concrete is not a homogenous material. In truth, an unlimited number of co</p><p>　　Much the same can be said of asphalt—technically, asphaltic concrete—which is also a mixture of aggregate (gravel o

13、r crushed stone), sand, and cement (asphalt binder); economics promote the use of locally available materials; and the underlying chemistry is not well understood. The characteristics of asphalt binder, for instance, var

14、y depending on the source of crude oil from which it is derived.</p><p>　　The metallurgy of steel is probably better understood than the chemistry of either asphalt or concrete, but it too is a mixture with

15、virtually limitless combinations. Strength, toughness, corrosion resistance, and weldability are some of the performance characteristics that vary with the type of steel alloy used and the intended applications.</p>

16、;<p>　　As uses evolve and economic conditions change, we have a continuing need for a more sophisticated understanding of these common materials. Even though they are “mature” products, there is still room for sig

17、nificant incremental improvements in their performance. Because fundamental knowledge is still wanting, there is also considerable potential for breakthroughs in their performance.</p><p>　　Factors That Affe

18、ct Highway Construction</p><p>　　All other things being equal, stronger, longer lasting, less costly highway materials are desirable and, given the quantities involved, there are plenty of incentives for inn

19、ovation. In highway transportation, however, all other things are not equal. A number of other factors contribute to the urgent and continuing need for innovation.</p><p>　　First, traffic volume and loadings

20、 continue to increase. Every day the U.S. highway network carries more traffic, including heavy trucks that were unimagined when the system was originally conceived and constructed. The 47,000-mile interstate highway sys

21、tem today carries more traffic than the entire U.S. highway system carried in 1956 when the interstates were laid out. The U.S. Department of Transportation (DOT) estimates that in metropolitan areas the annual cost of t

22、raffic congestion for busi</p><p>　　On rural interstates, overall traffic more than doubled between 1970 and 2005; at the same time, the loadings on those highways increased six-fold, mainly due to the incre

23、ase in the number of trucks and the number of miles they travel. (Truck traffic increased from about 5.7 percent of all vehicle-miles traveled on U.S. highways in 1965 to 7.5 percent in 2000 [FHWA, 2005]).</p><

24、;p>　　Second, traffic disruptions must be kept to a minimum during construction. Our overstressed highway system is not very resilient. Thus disruptions of any sort, such as lane and roadway closings, especially in maj

25、or metropolitan areas and on key Interstate routes, can cause massive traffic snarls. This means that repair and reconstruction operations must often be done at night, which introduces a variety of additional complexitie

26、s and safety issues. Occasionally, heroic measures must be taken to </p><p>　　Third, environmental, community, and safety requirements have become more stringent. For many good reasons, expectations of what

27、a highway should be, how it should operate, and how it should interact with the environment and adjacent communities are constantly evolving. Designs to promote safety, measures to mitigate a growing list of environmenta

28、l impacts, and attention to aesthetics have fundamentally changed the scope of major highway projects in the United States. For example, on Maryland’s </p><p>　　Fourth, costs continue to rise. Building and m

29、aintaining highways cost effectively is an ever-present goal of good engineering. But cost increases in highway construction have been extraordinary due in part to the expanded scope of highway projects and construction

30、in demanding settings. In addition, the costs of the mainstay materials—portland cement, asphalt binder, and steel—have risen dramatically as the world, particularly China, has gone on a construction binge. The Federal H

31、ighway Adminis</p><p>　　Fortunately, research and innovation in construction have never stopped, although they are not always sufficiently funded and they seem to fly beneath the radar of many scientists and

32、 engineers. Nevertheless, there have been great successes, which are cumulatively changing how highways are built in America.</p><p>　　The Superpave Design System</p><p>　　In response to widespr

33、ead concerns about premature failures of hot-mix asphalt pavements in the early 1980s, a well funded, congressionally mandated, crash research program was conducted to improve our understanding of asphalt pavements and t

34、heir performance. The seven-year Strategic Highway Research Program (SHRP), which was managed by the National Research Council, developed a new system of standard specifications, test methods, and engineering practices f

35、or the selection of materials and the </p><p>　　The new system has improved matches between combinations of asphalt binder and crushed stone and the climatic and traffic conditions on specific highways. Stat

36、e departments of transportation (DOTs) spend more than $10 billion annually on these pavements, so even modest improvements in pavement durability and useful life can lead to substantial cost savings for agencies and tim

37、e savings for motorists (TRB, 2001).</p><p>　　SHRP rolled out the Superpave system in 1993, but it took years for individual states and their paving contractors to switch to the new system, which represents

38、a significant departure, not only in design, but also in the procedures and equipment used for testing. Each state DOT had to be convinced that the benefits would outweigh the modest additional costs of Superpave mixes,

39、as well as the time and effort to train its staff and acquire necessary equipment.</p><p>　　A survey in 2005 showed that 50 state DOTs (including the District of Columbia and Puerto Rico) were using Superpav

40、e (Figure 1). The remaining two states indicated that they would be doing so by the end of 2006. Throughout the implementation period, researchers continued to refine the system (e.g., using recycled asphalt pavements in

41、 the mix design [TRB, 2005]).</p><p>　　It may be years before the cost benefits of Superpave can be quantified. A 1997 study by the Texas Transportation Institute projected that, when fully implemented, Supe

42、rpave’s annualized net savings over 20 years would approach $1.8 billion annually—approximately $500 million in direct savings to the public and $1.3 billion to highway users (Little et al., 1997).</p><p>　　

43、Moreover, analyses by individual states and cities have found that Superpave has dramatically improved performance with little or no increase in cost. Superpave is not only an example of a successful research program. It

44、 also demonstrates that a vigorous, sustained technology-transfer effort is often required for innovation in a decentralized sector, such as highway transportation.</p><p>　　Prefabricated Components</p>

45、;<p>　　The offsite manufacturing of steel and other components of reinforced concrete for bridges and tunnels is nothing new. But the need for reconstructing or replacing heavily used highway facilities has increa

46、sed the use of prefabricated components in startling ways. In some cases components are manufactured thousands of miles from the job site; in others, they are manufactured immediately adjacent to the site. Either way, we

47、 are rethinking how design and construction can be integrated.</p><p>　　When the Texas Department of Transportation needed to replace 113 bridge spans on an elevated interstate highway in Houston, it found t

48、hat the existing columns were reusable, but the bent caps (the horizontal connections between columns) had to be replaced. As an alternative to the conventional, time-consuming, cast-in-place approach, researchers at the

49、 University of Texas devised new methods of installing precast concrete bents. In this project, the precast bents cut construction time from 18 m</p><p>　　As part of a massive project to replace the San Fran

50、cisco-Oakland Bay Bridge, the California Department of Transportation and the Bay Area Toll Authority had to replace a 350-foot, 10-lane section of a viaduct on Yerba Buena Island. In this case, the contractor, C.C. Myer

51、s, prefabricated the section immediately adjacent to the existing viaduct. The entire bridge was then shut down for the 2007 Labor Day weekend, while the existing viaduct was demolished and the new 6,500-ton segment was

52、“rolled”</p><p>　　Probably the most extensive and stunning collection of prefabricated applications on a single project was on the Central Artery/Tunnel Project (“Big Dig”) in Boston. For the Ted Williams Tu

53、nnel, a dozen 325-foot-long steel tunnel sections were constructed in Baltimore, shipped to Boston, floated into place, and then submerged. However, for the section of the tunnel that runs beneath the Four Points Channel

54、, which is part of the I-90 extension, bridge restrictions made this approach infeasible. I</p><p>　　An even more complicated process was used to build the extension tunnel under existing railroad tracks, wh

55、ich had poor underlying soil conditions. Concrete and steel boxes were built at one end of the tunnel, then gradually pushed into place through soil that had been frozen using a network of brine-filled pipes (Vanderwarke

56、r, 2001).</p><p>　　Specialty Portland Cement Concretes</p><p>　　New generations of specialty concretes have improved one or more aspects of performance and allow for greater flexibility in highw

57、ay design and construction. High-performance concrete typically has compressive strengths of at least 10,000 psi. Today, ultra-high-performance concretes with formulations that include silica fume, quartz flour, water re

58、ducers, and steel or organic fibers have even greater durability and compressive strengths up to 30,000 psi. These new concretes can enable constructi</p><p>　　Latex-modified concrete overlays have been used

59、 for many years to extend the life of existing, deteriorating concrete bridge decks by the Virginia DOT, which pioneered the use of very early strength latex-modified concretes for this application. In high-traffic situa

60、tions, the added costs of the concrete have been more than offset by savings in traffic-control costs and fewer delays for drivers (Sprinkel, 2006).</p><p>　　When the air temperature dips below 40， costly in

61、sulation techniques must be used when pouring concrete for highway projects. By using commercially available admixtures that depress the freezing point of water, the U.S. Cold-Weather Research and Engineering Laboratory

62、has developed new concrete formulations that retain their strength and durability at temperatures as low as 23?F. Compared to insulation techniques, this innovation has significantly decreased construction costs and exte

63、nded the co</p><p>　　As useful as these and other specialty concretes are, nanotechnology and nanoengineering techniques, which are still in their infancy, have the potential to make even more dramatic impro

64、vements in the </p><p>　　performance and cost of concrete.Waste and Recycled Materials</p><p>　　Highway construction has a long history of using industrial waste and by-product materials. The mo

65、tivations of the construction industry were simple—to help dispose of materials that are otherwise difficult to manage and to reduce the initial costs of highway construction. The challenge has been to use these material

66、s in ways that do not compromise critical performance properties and that do not introduce substances that are potenti-ally harmful to people or the environment. At the same time, as</p><p>　　Research and de

67、monstration projects have generated many successful uses of by-product and recycled materials in ways that simultaneously meet performance, environmental, and economic objectives. For example, “crumb rubber” from old tir

68、es is increasingly being used as an additive in certain hot-mix asphalt pavement designs, and a number of patents have been issued related to the production and design of crumb rubber or asphalt rubber pavements (CDOT, 2

69、003; Epps, 1994).</p><p>　　Several states, notably California and Arizona, use asphalt rubber hot mix as an overlay for distressed flexible and rigid pavements and as a means of reducing highway noise. Mater

70、ials derived from discarded tires have also been successfully used as lightweight fill for highway embankments and backfill for retaining walls, as well as for asphalt-based sealers and membranes (Epps, 1994; TRB, 2001).

71、</p><p>　　Fly ash, a residue from coal-burning power plants, and silica fume, a residue from metal-producing furnaces, are increasingly being used as additives to portland cement concrete. Fly-ash concretes

72、can reduce alkali-silica reactions that lead to the premature deterioration of concrete (Lane, 2001), and silica fume is a component of the ultra-high-performance concrete described above.</p><p>　　After man

73、y years of experimentation and trials, reclaimed asphalt pavement (RAP) is now routinely used in virtually all 50 states as a substitute for aggregate and a portion of the asphalt binder in hot-mix asphalt, including Sup

74、erpave mixes. The reclaimed material typically constitutes 25 to 50 percent of the “new” mix (TFHRC, 1998). The National Asphalt Pavement Association estimates that 90 percent of the asphalt pavement removed each year is

75、 recycled and that approximately 125 millions tons </p><p>　　Visualization, Global Positioning Systems, and Other New Tools</p><p>　　For more than 20 years, highway engineers have used two-dimen

76、sional, computer-aided drafting and design (CADD) systems to accelerate the design process and reduce costs. The benefits of CADD systems have derived essentially from automating the conventional design process, with eng

77、ineers doing more or less what they had done before, although much faster and with greater flexibility.</p><p>　　New generations of three- and four-dimensional systems are introducing new ways of designing r

78、oads, as well as building them (Figure 4). For example, three-dimensional visualization techniques are clearly useful for engineers. But, perhaps more importantly, they have improved the communication of potential design

79、s to affected communities and public officials; in fact, they represent an entirely new design paradigm. Four-dimensional systems help engineers and contractors analyze the constructabil</p><p>　　Global posi

80、tioning systems are being used in surveying/layout, in automated guidance systems for earth-moving equipment, and for monitoring quantities. Other innovations include in situ temperature sensors coupled with data storage

81、, transmission, and processing devices that provide onsite information about the maturity and strength of concrete as it cures (Hannon, 2007; Hixson, 2006).</p><p>　　Conclusion</p><p>　　The exam

82、ples described above suggest the wide range of exciting innovations in the design and construction of highways. These innovations address materials, roadway and bridge designs, design and construction methods, road safet

83、y, and a variety of environmental, community, and aesthetic concerns. Looking to the future, however, challenges to the U.S. highway system will be even more daunting—accommodating more traffic and higher loadings; reduc

84、ing traffic disruptions during construction; meeting</p><p><b>　　中文翻譯</b></p><p>　　高速公路設(shè)計與施工：創(chuàng)新的挑戰(zhàn)</p><p>　　作者：小羅伯特·E·斯金納</p><p>　　研究方式的創(chuàng)新和進(jìn)步正在改變著

85、美國公路建設(shè)的方式。</p><p>　　埃及人在公元前2500年時就會澆筑混凝土，羅馬人也曾用它建造神殿和斗獸場。到了19世紀(jì)中葉，歐洲人開始使用混凝土造橋，并且在19世紀(jì)后半葉出現(xiàn)了一個“現(xiàn)代化”的混凝土公路，數(shù)千年前自然產(chǎn)生的瀝青已被用來防水，而進(jìn)入正常的公路建設(shè)中則是在19世紀(jì)，1774年世界上第一座鐵橋建成，但是截至19世紀(jì)末期，在橋梁施工中鋼材在很大程度上替代了鐵。而現(xiàn)在，混凝土，瀝青，鋼材這些材料是

86、全世界公路橋梁和公共基礎(chǔ)設(shè)施建設(shè)中使用的主要材料，混凝土和鋼材是在橋梁和公路建設(shè)中應(yīng)用最廣泛的。</p><p>　　大家都熟悉混凝土，瀝青和鋼筋，我們其中的一些人的工作正與其有關(guān)，也許是家庭裝飾工程，這個很熟悉，再加上他們悠久的歷史和廣泛的用途導(dǎo)致很多精明的人都認(rèn)為這些材料都是很好理解的，他們的表現(xiàn)可以很容易和可靠的預(yù)測，應(yīng)用于告訴公路方面的技術(shù)性的挑戰(zhàn)也是在很久前已被克服。然而，這種觀念很大程度上是錯誤的和有

87、誤導(dǎo)性的。</p><p>　　例如，考慮到混凝土是由普通硅酸鹽水泥，沙子，骨料（碎石或片石）和水混合而成的一種混合物。其性能特點是由其組成的材料的比例和材料本身的特點以及如何混合而決定。混凝土的基本化學(xué)反應(yīng)是非常的復(fù)雜的，很難完全了解，而且還和石材的類型有關(guān)?？梢蕴砑愉摻顏碓黾踊炷恋目估瓘?qiáng)度（鋼筋混凝土），可以在特定的應(yīng)用程序和條件下加上確定各種添加劑來改善混凝土的和易性和性能。動容循環(huán)的環(huán)境條件和其中化學(xué)反

88、應(yīng)可導(dǎo)致過度負(fù)荷對混凝土產(chǎn)生破壞和惡化。</p><p>　　諸多因素促成了公路建設(shè)迫切需要創(chuàng)新。</p><p>　　混泥土是繼水之后世界上最常被使用的材料。每年，全世界需要16億噸水泥，100億噸沙粒和碎石子，以及10億噸的水來制造混泥土。基于運(yùn)輸費(fèi)用的考慮，即使有時候石頭的質(zhì)量并不如意，在經(jīng)濟(jì)的壓力下，大多數(shù)人會選擇使用當(dāng)?shù)夭牧稀Ｒ虼?，各地的混泥土也都是不一樣的。事實上，各種組合和配

89、方都是可能的。</p><p>　　而必須是一致的是瀝青的配方，技術(shù)上說也就是瀝青混泥土。它是由砂石混合物，沙粒和瀝青包裹的水泥混合而成的。出于經(jīng)濟(jì)效益的考慮，人們趨向于使用當(dāng)?shù)刭Y源，但是瀝青混泥土的深沉化學(xué)原理確不為人們所了解。例如，瀝青的特性會根據(jù)它原油的出處不同而變化。</p><p>　　相對于瀝青和混泥土，鋼材的冶煉可能更如容易被理解，但是同樣的，鋼材也是由大量的混合物組合而成的

90、。鋼材的強(qiáng)度，張力，防腐蝕度，可焊接度以及其他的質(zhì)量特性會因為選用的合金類型和它的使用用途而有所不同。</p><p>　　由于用途和經(jīng)濟(jì)條件的變化，我們需要對于這么材料擁有更持續(xù)和更成熟的了解。即使材料本身已經(jīng)成形，仍然有很大的提升空間。因為我們?nèi)孕枰纠碚摚赃@里仍有很大可以考慮的潛力去挖掘。</p><p>　　公路建設(shè)的影響因素 </p><p>　　

91、所有的其他方面是平等的，更強(qiáng)的，更持久的，成本更低的公路材料均是可取的，而其中所涉及的東西也有很多事創(chuàng)新的和值得激勵的。然后，在公路運(yùn)輸發(fā)展中，所有其他事情都不可同日而語的，還有其他很大一部分因素緊急和持續(xù)創(chuàng)新的。 </p><p>　　首先，交通量和交通負(fù)荷會持續(xù)增加。現(xiàn)在每天美國的公路網(wǎng)路中承載更多的交通量，包括在當(dāng)初構(gòu)造的系統(tǒng)當(dāng)中難以想象的重型卡車。如今的470

92、00英里的州際公路系統(tǒng)承載的交通量超越了美國在1956年全國的公路系統(tǒng)，在當(dāng)時洲際公路并未成型。美國交通部估計，在大都市市區(qū)的交通堵塞，讓企業(yè)和公民每年支出的費(fèi)用將近170億美元。而在農(nóng)村的洲際公路上，在1970年到2005年期間建設(shè)里程翻了一番，而與此同時這些公路的負(fù)荷卻增長了6倍，這主要是因為卡車的數(shù)量和運(yùn)行的公里數(shù)的增加（汽車流量增加【FHWA在1965年的7.5%，2000年的5.7%，2005】）</p><

93、;p>　　其次，在施工期間交通中斷必須保持在最低限度內(nèi)。我們重點強(qiáng)調(diào)的公路系統(tǒng)是應(yīng)該非常有彈性的。如車道和道路的關(guān)閉現(xiàn)象，尤其像是在大城市地區(qū)的主要洲際公路的路線上，任何形式的交通中斷都會因此造成大規(guī)模的交通堵塞。這也意味著一些公路的重建和補(bǔ)修必須是在夜間進(jìn)行，同時也引進(jìn)了另外的關(guān)于施工復(fù)雜性和安全性各種措施。偶然也需要果斷的采取措施，保持詩歌期間的交通通暢。例如在波斯頓的“大整修”的建設(shè)工程過程中，高架橋中央干道是連續(xù)服務(wù)的，直

94、到它下面的隧道建成為止。</p><p>　　第三，環(huán)境，社會和安全方面的要求也是越來越嚴(yán)格。對于期望一條公路應(yīng)該是什么，它是如何運(yùn)作，它應(yīng)該與環(huán)境以及鄰近社區(qū)的不斷發(fā)展都要有很好的理由。良好的設(shè)計可以促進(jìn)道路安全，采取措施減輕多環(huán)境的影響以及關(guān)注美學(xué)這些可以從根本上改變美國范圍內(nèi)的主要公路項目。例如，在馬里蘭州的2.4億美元的intercounty在華盛頓特區(qū)的郊區(qū)，這是正在建設(shè)中的連接器項目，就環(huán)境緩解方面就

95、占有15%的項目費(fèi)用，約合15萬美元每英里（AASHTO標(biāo)準(zhǔn)，2008年）</p><p>　　第四，由于成本的不斷上升有效的建設(shè)和維護(hù)公路建設(shè)的成本是永遠(yuǎn)存在的良好的工程目標(biāo)。但是在公路建設(shè)中的成本增加主要的原因是由于公路建設(shè)項目的建設(shè)要求設(shè)置的范圍的擴(kuò)大。此外，如主題材料，硅酸鹽水泥，瀝青粘結(jié)劑，鋼材等成本上升也非常顯著，縱觀世界，尤其是中國已經(jīng)形成了建設(shè)的熱潮。聯(lián)邦公路管理局的硅酸鹽水泥混泥土路面，瀝青路面

96、，結(jié)構(gòu)鋼在1995年到2005期間的成本指數(shù)上升了51%，58%和70%（FHWA，2006年）</p><p>　　幸運(yùn)的是，在建設(shè)中的研究和創(chuàng)新從來美元停止過，雖然他們并不是總是有足夠的資金，似乎許多的科學(xué)家和工程師都是在雷達(dá)下面飛行，但是這已經(jīng)有了巨大的成就，這些成就正在累積著如何改變美國的高速公路。</p><p>　　Superpave設(shè)計系統(tǒng)</p><p&

97、gt;　　在20世紀(jì)的80年代，關(guān)于回答關(guān)于熱拌瀝青路面的過早失效引起廣泛的關(guān)注，由國會授權(quán)并有充足的資金支持的研究計劃，目的來改善我們隊瀝青路面的理解和發(fā)現(xiàn)，這就是7年戰(zhàn)略公路研究計劃。（SHRP），是由國家研究理事會管理和開發(fā)新的標(biāo)準(zhǔn)規(guī)范，測試方法，材料的選擇和配比用于瀝青路面的工程實踐新系統(tǒng)提高了瀝青粘合劑之間和碎石之間的組合，在特定公路的氣候條件和交通條件下進(jìn)行匹配。國家運(yùn)輸部門（DOTS），每年花費(fèi)超過10億美元對這些路面的耐