城市交通規(guī)劃外文翻譯

1、<p>　　本科畢業(yè)設(shè)計(jì)（論文）</p><p>　　河南理工大學(xué)土木工程學(xué)院</p><p>　　二○ 年 月 日</p><p>　專業(yè)名稱：土木工程</p><p>　年級(jí)班級(jí)：</p><p>　學(xué)生姓名：</p><p>　指導(dǎo)教師：</p><

2、;p>　　Urban transportation Planning</p><p>　　An urban transportation system is basic component of an urban area's social，economic，and physical structure. Not only does the design and performance of a t

3、ransportation system provide opportunities for mobility，but over the long term，it influences patterns of growth and the level of economic activity through the accessibility it provides to land. Planning for the developme

4、nt or maintenance of the urban transportation system is thus an important activity，both for promoting the efficient movement</p><p>　　There are several basic concepts about an urban transportation system tha

5、t should be kept in mind. Most important，a transportation system in an urban area is defined as consisting of the facilities and services that allow travel throughout the region，providing opportunities for:(I)mobility to

6、 residents of an urban area and movement of goods and (2) accessibility to land .Given this definition，an urban transportation system can be further characterized by three major components: the spatial confi</p>&

7、lt;p>　　The Spatial Configuration of a Transportation System</p><p>　　One way to describe the spatial dimension of an urban transportation system is to consider the characteristics of individual trips from

8、 an origin to a destination. For example, a trip can consist of several types of movement undertaken to achieve different objectives. Travelers leaving home might use a local bus system to reach a suburban subway statio

9、n(a trip collection process)，proceed through the station to the subway platform (a transfer process)，ride the subway to a downtown station (a lin</p><p>　　The facilities and services that provide these oppor

10、tunities for travel，when interconnected to permit movement from one location to another，form a network. Thus，another way of representing the spatial dimension of an urban transportation system is as a set of road and tra

11、nsit networks. Even in the smallest urban areas，where mass transit is not available，the local street network provides the basic spatial characteristic of the transportation system.</p><p>　　The transportatio

12、n system of a city can influence the way in which the city's social and economic structure, often called the urban activity system，develops. At the same time，changes in this structure can affect the ability of the t

13、ransportation system to provide mobility and accessibility. Thus , the transportation system is closely related to the urban activity system and; historically, has been an important determinant of urban form.</p>

14、<p>　　Because of the relation between transportation and urban activities，many of the methods used by transportation planners depend on estimates of trips generated by specific land uses. The relation also suggests

15、 that the options available to public officials dealing with transportation problems should include not only those related directly to the transportation system, but also actions such as zoning that affect the distributi

16、on of land use, and thus influence the performance of the transportation</p><p>　　The foregoing considerations point to two important principles for transportation planning: The transportation system should

17、be </p><p>　　Considered as an integral part of the social and economic system in an urban area.</p><p>　　Viewed as a set of interconnected facilities and services designed to provide opportuniti

18、es for travel from one location to another.</p><p>　　The Technology of Urban Transportation </p><p>　　The technology of urban transportation is closely related to the spatial configuration of th

19、e transportation system in that the design transportation networks reflects the speed, operating , and cost characteristics of the vehicle or mode of transportation being used. Technology includes the means of propulsion

20、, type of support，means of guidance，and control technique.</p><p>　　The development and widespread use of electric streetcars in urban areas during the late nineteenth century was a technological innovation

21、that initiated the transformation of most North American cities. The advent of the electric streetcar permitted urban areas to expand beyond the boundaries that had been dictated by previous transportation technologies

22、(e. g.，walking，horse，horsecar)，spawning `streetcar suburbs' with dramatically lower residential densities along streetcar lines radiating fro</p><p>　　The success of the streetcar in providing access fro

23、m selected suburban areas to central business districts was followed by public acceptance of a second major technological innovation-the automobile，powered by the internal combustion engine. Increasing consumer preferenc

24、es for lower-density living and for an ability to travel beyond established urban boundaries sparked a phenomenal growth in automobile ownership and usage，beginning in the 1920s . ④The automobile continues and accelerate

25、d the ev</p><p>　　The technology of the internal-combustion engine，however, also led to the decline of other transportation modes used in urban areas by providing a less expensive and more flexible replaceme

26、nt for rail-based modes. While the automobile provided new opportunities for personal mobility and urban growth, motor buses rapidly replaced electric streetcars, to the extent that only five North American cities today

27、still operate large-scale streetcar systems-Boston, Philadelphia, Pittsburgh, Toronto, and </p><p>　　The technologies and the resulting modes available today for urban transportation are common to most citie

28、s but are often applied in different ways to serve different purposes. It should be noted that certain types of modes are appropriate than others in serving different types of urban trips.</p><p>　　The techn

29、ological dimension of the urban transportation system suggests a third principle for urban transportation planning:</p><p>　　Transportation planners must consider the transportation system as consisting of d

30、ifferent modes , each having different operational and cost characteristics.</p><p>　　From; Michael D. Meyer and Eric J. Miller "Urban Transportation Planning", 1984</p><p><b>　

31、　城市交通規(guī)劃</b></p><p>　　城市交通系統(tǒng)是市區(qū)的社會(huì)、經(jīng)濟(jì)、和物質(zhì)結(jié)構(gòu)的一個(gè)基本組成部分。一個(gè)交通系統(tǒng)的設(shè)計(jì)和實(shí)施不僅為流動(dòng)性提供機(jī)會(huì)，并且從長(zhǎng)遠(yuǎn)觀點(diǎn)來看，通過它能對(duì)土地提供良好使用價(jià)值也使經(jīng)濟(jì)活動(dòng)和發(fā)展受到益處。這樣，為了發(fā)展和維護(hù)城市交通系統(tǒng)而制定的規(guī)劃是一項(xiàng)重要的活動(dòng)，既是為了促進(jìn)人和貨物在市區(qū)的有效運(yùn)轉(zhuǎn)，同時(shí)也是為了保持交通在實(shí)現(xiàn)其他社團(tuán)目標(biāo)方而所能起到的強(qiáng)有力的支援作用。&l

32、t;/p><p>　　對(duì)于城市交通系統(tǒng)有幾個(gè)基本概念是應(yīng)該記住的。最重要的是,一個(gè)城市的交通系統(tǒng)被認(rèn)為是包括交通設(shè)施和服務(wù),這兩者有助于貫穿全區(qū)的出行，并且為以下兩方面提供機(jī)會(huì):(1)居民的流通量和商品的運(yùn)轉(zhuǎn)，(2)對(duì)于土地的可達(dá)性。鑒于這種認(rèn)識(shí),城市交通系統(tǒng)可以進(jìn)一步分解為以下三個(gè)部分:空間布置,可使一點(diǎn)到另一點(diǎn)的出行成為可能；交通技術(shù),提供兩地區(qū)運(yùn)轉(zhuǎn)的手段；機(jī)構(gòu)的機(jī)制，提供交通系統(tǒng)設(shè)施的規(guī)劃、建設(shè)、運(yùn)營(yíng)和維護(hù)。&

33、lt;/p><p><b>　　交通系統(tǒng)的空間布置</b></p><p>　　描述一個(gè)城市交通系統(tǒng)的空間尺度的方式是考慮一個(gè)人由起點(diǎn)到目的地的出行特點(diǎn)。例如，出行可以包括為達(dá)到不同目的的幾種類型的流動(dòng)。離開家的出行者可以乘坐當(dāng)?shù)氐墓财嚩竭_(dá)另一個(gè)郊區(qū)地鐵車站（出行集合過程），經(jīng)車站轉(zhuǎn)到地鐵站臺(tái)（換乘過程），乘地鐵到達(dá)一個(gè)商業(yè)車站（沿線運(yùn)行過程），然后步行到工作地點(diǎn)（

34、分散過程）。相似的，人們可以把乘汽車由家到工作地點(diǎn)的出行看作是包括相似的過程，利用當(dāng)?shù)氐慕值老到y(tǒng)實(shí)現(xiàn)出行集合過程，高速公路提供線路的出行能力，在商業(yè)中心區(qū)的停車場(chǎng)起到換乘點(diǎn)的作用，而步行與前面說的一樣，起到分散作用。</p><p>　　當(dāng)提供這些出行機(jī)會(huì)的公共設(shè)施和服務(wù)集合起來,使從一個(gè)地點(diǎn)到另一個(gè)地點(diǎn)的運(yùn)動(dòng)成為可能時(shí)就會(huì)形成網(wǎng)絡(luò)。這樣，表示一個(gè)城市交通系統(tǒng)的空間尺度的另一種方式是一組道路和公共交通的網(wǎng)絡(luò)系統(tǒng)。

35、甚至在不能利用公共交通的很小的市區(qū)內(nèi)，當(dāng)?shù)氐慕值谰W(wǎng)絡(luò)也會(huì)提供交通系統(tǒng)的基本空間特征。</p><p>　　城市交通系統(tǒng)將會(huì)影響到城市的社會(huì)和經(jīng)濟(jì)結(jié)構(gòu)（通常被稱為城市活動(dòng)系統(tǒng)）的發(fā)展方式。同時(shí),這種結(jié)構(gòu)的變化會(huì)影響交通系統(tǒng)提供流動(dòng)性和可達(dá)性的能力。因此,交通系統(tǒng)是與城市活動(dòng)系統(tǒng)密切相關(guān)的;從歷史上看,城市交通系統(tǒng)曾經(jīng)是一個(gè)決定城市形態(tài)的重要因素。</p><p>　　由于交通和城市活動(dòng)之間的

36、關(guān)系，許多交通規(guī)劃人員所使用的方法取決于特定的土地利用所產(chǎn)生的出行評(píng)估。這個(gè)關(guān)系還暗示可供與交通問題打交道的政府官員多采用的選擇方案。而且也應(yīng)該包括，例如，影響土地利用分布的區(qū)域劃分，并因此影響到交通系統(tǒng)特性的一些措施。</p><p>　　上述的考慮指出用于交通規(guī)劃的兩個(gè)重要原則：</p><p>　　被認(rèn)為是市區(qū)社會(huì)和經(jīng)濟(jì)系統(tǒng)的一個(gè)完整部分。</p><p>　

37、　被視為目的在于提供從一個(gè)地點(diǎn)到另一個(gè)地點(diǎn)出行機(jī)會(huì)的一套互相結(jié)合的交通設(shè)施和服務(wù)。</p><p><b>　　城市交通的技術(shù)</b></p><p>　　城市交通技術(shù)是同交通系統(tǒng)的空間布局緊密相關(guān)的，其中交通網(wǎng)設(shè)計(jì)反映車輛的速度、運(yùn)行和費(fèi)用特征所采用的交通模式。技術(shù)上包括推進(jìn)的手段。支撐的類型引導(dǎo)的手段，以及控制技術(shù)。</p><p>　　十

38、九世紀(jì)晚期，在市區(qū)發(fā)展和廣泛使用有軌電車是一項(xiàng)技術(shù)創(chuàng)新，啟動(dòng)了北美大多數(shù)城市的轉(zhuǎn)型。有軌電車的出現(xiàn)使城市地區(qū)超出了之前運(yùn)輸技術(shù)（例如走路、騎馬、馬車）所限定的界限進(jìn)行了擴(kuò)展。產(chǎn)生了大量的居住密度明顯很低的位于由市中心輻射出去的電車電車路線沿線的“電車郊區(qū)”。與此同時(shí)，許多工業(yè)也從由市中心延伸出去的提路沿線疏散了，工人們起初需要在這些工廠附近居住，現(xiàn)在引進(jìn)了電車，住的遠(yuǎn)也沒有什么關(guān)系了。</p><p>　　在電車

39、提供由經(jīng)過挑選的郊區(qū)到中心商業(yè)區(qū)的道路取得成功后，接著是公眾對(duì)于第二個(gè)重大技術(shù)革新，即對(duì)內(nèi)燃機(jī)為動(dòng)力的汽車的歡迎。消費(fèi)者越來越多的對(duì)于低密度的居住生活的熱愛，以及對(duì)于跨越已確定的城市邊界出行能力的偏愛，促進(jìn)了從二十年代開始的汽車購(gòu)置和使用方便急劇增長(zhǎng)。汽車的可用性促使市區(qū)進(jìn)一步擴(kuò)展，并且更重要的是，汽車為通向市中心的放射狀電車線和鐵路路線之間地區(qū)的可能性提供條件。</p><p>　　然而，由于內(nèi)燃機(jī)技術(shù)提供了比

40、有軌交通方式更為廉價(jià)的和更為靈活的汽車，從而導(dǎo)致了市區(qū)內(nèi)其他交通方式的衰落。在汽車為個(gè)人流通和和城市發(fā)展提供了新機(jī)會(huì)的同時(shí)，公共汽車很快取代了電車，以致目前只有五個(gè)北美城市還在使用大型電車系統(tǒng)，即波士頓、費(fèi)城、匹茨堡、多倫多和舊金山（不過近年來這種趨勢(shì)又有點(diǎn)逆轉(zhuǎn)，新型“輕軌”系統(tǒng)正在埃德蒙頓、卡爾加里、圣地亞哥和布法羅運(yùn)營(yíng)）。于此同時(shí)，特別是自第二次世界大戰(zhàn)結(jié)束以來，私人汽車使用的增長(zhǎng)，一般來說已顯著的使公共交通的使用縮減。根據(jù)最近的統(tǒng)

41、計(jì)數(shù)字，在1980年有六千二百三十萬美國(guó)人每天是自己駕駛汽車上班，另外有一千九百萬人合伙使用汽車，而有六百萬人乘用公共交通。</p><p>　　當(dāng)前可以應(yīng)用的城市交通技術(shù)和交通模式，對(duì)于大多數(shù)城市來說是通用的，但也常常以不同的方式應(yīng)用，為不同的目的服務(wù)。應(yīng)當(dāng)注意到，某些交通方式較其他方式更適合于承擔(dān)不同類型的城市出行。</p><p>　　城市交通系統(tǒng)的技術(shù)方面提出一個(gè)用于城市交通規(guī)劃的

42、第三個(gè)原則：</p><p>　　交通規(guī)劃人員應(yīng)當(dāng)認(rèn)為交通系統(tǒng)包括不同的交通方式，每一個(gè)方式具有不同的運(yùn)營(yíng)和費(fèi)用特征。 </p><p>　　摘自：邁克爾 D.梅耶和艾瑞克 J.米勒《城市交通規(guī)劃》，1984</p><p>　　Traffic signals</p><p>　　In the United States alone ,som

43、e 250,000 intersections have traffic signals , which are defined as all power-operated traffic-control devices except flashers，signs，and markings for directing or warning motorists, cyclists，or pedestrians.</p>&l

44、t;p>　　Signals for vehicular，bicycle，and pedestrian control are ‘pretimed’ where specific times intervals are allocated to the various traffic movements and as 'traffic actuated' where time intervals are contro

45、lled in whole or in part by traffic demand. </p><p>　　Pretimed Traffic Signals</p><p>　　'Pretimed' traffic signals are set to repeat regularly a given sequence of signal indications for

46、stipulated time intervals through the 24-hr day. They have the advantages of having controllors of lower first cost and that they can be interconnected and coordinated to vehicles to move through a series of intersection

47、s with a minimum of stops and other delays. Also, their operation is unaffected by conditions brought on by unusual vehicle behavior such as forced stops，which，with some traffic-actu</p><p>　　‘Cycle length’

48、the time required for a complete sequence of indications, ordinarily falls between 30 and 120s. Short cycle lengths are to be preferred, as the delay to standing vehicles is reduced. With short cycles, however a relativ

49、ely high percentage of the total time is consumed in clearing the intersection and starting each succeeding movement. As cycle length increases, the percentage of time lost from these causes decreases. With high volumes

50、of traffic, it may be necessary to increase t</p><p>　　Each traffic lane of a normal signalized intersection can pass roughly one vehicle each 2.1s of green light. The yellow (caution) interval following eac

51、h green period is usually between 3 and 6s，depending on street width，the needs of pedestrians, and vehicle approach speed. To determine an approximate cycle division, it is common practice to make short traffic counts du

52、ring the peak period. Simple computations give the number of vehicles to be accommodated during each signal indication and the m</p><p>　　At many intersections，signals must be timed to accommodate pedestrian

53、 movements. The Manual recommends that the minimum total time allowed be an initial interval of 4 to 7s for pedestrians to start plus walking time computed at 4 ft/s (1. 2m/s). With separate pedestrian indicators，the WA

54、LK indication(lunar white) covers the first of these intervals, and flashing DON'T WALK (Portland orange ) the remainder. The WALK signal flashes when there are possible conflicts with vehicles and is steady whe</

55、p><p>　　If pedestrian control is solely by the vehicle signals，problems develop if the intersection is wide, since the yellow clearance interval will have to be considerably longer than the 3 to 5s needed by ve

56、hicles. This will reduce intersection capacity and may call for a longer cycle time. On wide streets having a median at least 6 ft (1. 8m)wide，pedestrians may be stopped there. A separate pedestrian signal activator must

57、 be placed on this median if pedestrian push buttons are incorporated into the</p><p>　　Coordinated Movement</p><p>　　Fixed-time traffic signals along a street or within an area usually are coor

58、dinated to permit compact groups of vehicles called `platoons’to move along together without stopping. Under normal traffic volumes，properly coordinated signals at intervals variously estimated from 2500 ft (0. 76km)to m

59、ore than a mile (1. 6km) are very effective in producing a smooth flow of traffic. On the other hand，when a street is loaded to capacity，coordination of signals is generally ineffective in producing smoot</p><

60、p>　　Four systems of coordination-simultaneous, alternate，limited progressive, and flexible progressive-have developed over time. The simultaneous system made all color indications on a given street alike at the same t

61、ime .It produced high vehicle speeds between stops but low overall speed. Because of this and other faults，it is seldom used today.</p><p>　　The alternate system has all signals change their indication at th

62、e same time，but adjacent signals or adjacent groups of signals on a given street show opposite colors. The alternate system works fairly well on a single street that has approximately equal block spacing. It also has bee

63、n effective for controlling traffic in business districts several blocks on a said, but only when block lengths are approximately equal in both directions. With an areawide alternate system，green and red indication</p

64、><p>　　The simple progressive system retains a common cycle length but provides 'go' indications separately at each intersection to match traffic progression. This permits continuous or nearly continuou

65、s flow of vehicle groups at a planned speed in at least one direction and discourages speeding between signals. Flashing lights may be substituted for normal signal indications when traffic becomes light.</p><

66、p>　　The flexible progressive system has a master controller mechanism that directs the controllers for the individual signals. This arrangement not only gives positive coordination between signals，but also makes prede

67、termined changes in cycle length，cycle split，and offsets at intervals during the day. For example，the cycle length of the entire system can be lengthened at peak hours to increase capacity and shortened at other times to

68、 decrease delays.</p><p>　　Flashing indications can be substituted when normal signal control is not needed. Also the offsets in the timing of successive signals can be adjusted to favor heavy traffic moveme

69、nts, such as inbound in the morning and outbound in the evening. Again，changes in cycle division at particular intersections can be made. The traffic responsive system is an advanced flexible progressive system with the

70、capacity to adjust signal settings to measured traffic volumes.</p><p>　　Where traffic on heavy-volume or high-speed arteries must be interrupted for relatively light cross traffic，semi-traffic-actuated sign

71、als are sometimes used. For them，detectors are placed only on the minor street. The signal indication normally is green on the main road and red on the cross street. On actuation, the indications are reversed for an appr

72、opriate interval after which they return to the original colors.</p><p><b>　　交通信號(hào)</b></p><p>　　僅在美國(guó)，約250000十字路口有交通信號(hào),這被定義為所有除了閃光燈、標(biāo)志、和標(biāo)記的用于指導(dǎo)或警告駕駛員、騎自行車的人和行人的電動(dòng)交通控制裝置,。</p>&l

73、t;p>　　控制車輛，騎自行車的人和行人的信號(hào)是在特定時(shí)間間隔分配到各種交通活動(dòng)的預(yù)定時(shí)間和在交通運(yùn)轉(zhuǎn)中控制全部或部分交通需求的的時(shí)間間隔。</p><p><b>　　定時(shí)交通信號(hào)</b></p><p>　　定時(shí)交通信號(hào)是設(shè)定為在一天二十四小時(shí)內(nèi)規(guī)定的時(shí)間定期重復(fù)一個(gè)規(guī)定的信號(hào)指示。它們有這些優(yōu)勢(shì)，包括有低生產(chǎn)成本的控制器，可以聯(lián)系和協(xié)調(diào)使車輛以最少的停靠和

74、其他的延遲通過一系列的交叉口。而且，它們的操作不受異常車輛行為引起的狀況的的影響，如一些交通信號(hào)控制裝置可能帶來的交通堵塞引起的強(qiáng)迫性停車。它們的劣勢(shì)是它們無法適應(yīng)交通流量的變化和在沒有其他交通的情況下約束一個(gè)方向的車輛。結(jié)果是導(dǎo)致交通不便和有時(shí)的通行能力下降。</p><p>　　一套完整順序的“周期時(shí)間”通常在30秒到120秒之間。當(dāng)車輛延遲減少，短循環(huán)時(shí)間是優(yōu)先考慮的。然而對(duì)于短循環(huán)，清理路口和開始每一次順

75、利的運(yùn)轉(zhuǎn)消耗的時(shí)間相對(duì)較高。當(dāng)循環(huán)周期增加，從這些原因失去的時(shí)間減少。對(duì)于高流量的交通，可能需要增加循環(huán)周期來獲得更大的通行能力。</p><p>　　每一個(gè)行車道信號(hào)正常的路口，一輛車在綠燈下大約2.1秒通過。根據(jù)街道寬度、行人需求和車輛靠近速度，每一個(gè)綠燈周期后的黃燈（警示）間隔在3秒到6秒之間。要確定一個(gè)大致的周期劃分，常見的做法是確定高峰期間的短期交通數(shù)目。簡(jiǎn)單的計(jì)算給出每一個(gè)適應(yīng)信號(hào)指示下車輛數(shù)目和車輛

76、通過時(shí)最小的綠燈時(shí)間。隨著現(xiàn)代控制設(shè)備，改變循環(huán)周期和每天時(shí)間次數(shù)的劃分，或者使閃光信號(hào)更好的適應(yīng)交通模式變的可能。</p><p>　　在許多路口，信號(hào)必須被定好來調(diào)整行人流動(dòng)。手冊(cè)建議行人開始加上步行時(shí)間以4英尺每秒（1.2米每秒）計(jì)算的最初的間隔允許的最小的總時(shí)間是4到7秒。對(duì)于單獨(dú)的行人指示，步行指示（淺白色）包括最開始的時(shí)間間隔，禁止通行閃光燈（橘黃色）包括了剩余的時(shí)間間隔。當(dāng)和車輛有可能的沖突步行信號(hào)

77、燈閃爍，當(dāng)沒有時(shí)步行信號(hào)燈不變。禁止通行信號(hào)穩(wěn)定不變時(shí)是告訴行人不要繼續(xù)前行。</p><p>　　如果行人完全由車輛信號(hào)控制，如果路口寬問題會(huì)變大，因?yàn)辄S燈間隔將大大高于車輛需要的3到5秒。這將減少交叉路口的通行能力，可能需要一個(gè)較長(zhǎng)的周期時(shí)間。有中線的寬闊街道至少要6英尺（1.8米）寬，行人可能停在那兒。如果行人命令按鈕被合并到整體的控制系統(tǒng)，一個(gè)單獨(dú)的行人信號(hào)必須放在這個(gè)街道中間。</p>&

78、lt;p><b>　　聯(lián)動(dòng)移動(dòng)</b></p><p>　　一個(gè)車道或一個(gè)區(qū)域的定時(shí)交通信號(hào)通常聯(lián)動(dòng)調(diào)來允許一排緊湊的車輛一起移動(dòng)而不停止。在正常的交通量下，適當(dāng)?shù)恼{(diào)整從2500英尺（0.76千米）到超過一英里（1.6千米）的各種信號(hào)間隔對(duì)于形成流暢的交通是非常有效的。另一方面，當(dāng)一個(gè)街道超過了通行能力，調(diào)整信號(hào)來形成流暢的交通一般是無效的。</p><p>　

79、　四個(gè)聯(lián)動(dòng)的，同步的，交互的，單一推進(jìn)式的和彈性連續(xù)前進(jìn)的信號(hào)系統(tǒng)隨著時(shí)間推移已經(jīng)開發(fā)出來。同步的系統(tǒng)使給定的街道在相同的時(shí)間內(nèi)所有的顏色指示相同。它出現(xiàn)在兩站之間車速高而整體速度低的街道上。因?yàn)檫@些和其他的錯(cuò)誤，今天已經(jīng)很少使用。</p><p>　　交互式系統(tǒng)在相同的時(shí)間有所有的信號(hào)轉(zhuǎn)換。但是在一個(gè)給定的街道附近的信號(hào)燈或者附近的信號(hào)群顯示互補(bǔ)的顏色。交互式系統(tǒng)在大約相等的街區(qū)間隔的信號(hào)街上能相當(dāng)好的工作。它

80、也能有效的在上述說明的商業(yè)區(qū)控制交通，但是只能當(dāng)長(zhǎng)度在兩個(gè)方向大約相等時(shí)才行。對(duì)于全區(qū)的交互式系統(tǒng)，綠色指示燈和紅色指示燈必須有大約相等的長(zhǎng)度。當(dāng)兩條主要街道相交，但是穿過主要街道的次要街道太多綠燈，這種周期劃分是令人滿意的。批評(píng)是在重交通量下后面區(qū)域的一排汽車必須強(qiáng)迫做出額外的停止，而改變交通狀況的調(diào)整是非常困難的。</p><p>　　簡(jiǎn)易連續(xù)式系統(tǒng)保持一個(gè)一般的周期時(shí)間，但是在每個(gè)交叉路口分別提供“前進(jìn)”指

81、示來匹配交通進(jìn)展。這允許在設(shè)計(jì)速度中的至少一個(gè)方向的一組車輛速度連續(xù)或接近連續(xù)流動(dòng)，并阻礙了信號(hào)之間的超速駕駛。當(dāng)交通變的輕的時(shí)候，閃爍的燈光可以取代正常的信號(hào)指示。</p><p>　　彈性連續(xù)前進(jìn)信號(hào)系統(tǒng)有一種主控制器裝置來指導(dǎo)個(gè)別信號(hào)控制器。這種布置不僅在信號(hào)之間做出了積極協(xié)調(diào)，而且使預(yù)定的周期長(zhǎng)度，周期分配，白天的時(shí)間間隔偏移的變化。例如，全部系統(tǒng)的周期長(zhǎng)度在高峰時(shí)段可以延長(zhǎng)來提升通行能力或者在其他時(shí)間縮

82、短來減少延遲。</p><p>　　當(dāng)正常的信號(hào)控制不需要，閃爍的信號(hào)指示可以被代替。而且連續(xù)信號(hào)偏移的計(jì)時(shí)可以進(jìn)行調(diào)整來適應(yīng)重交通，比如早上入境和晚上出境。此外，在特定交叉路口的分配周期可以被計(jì)算出來。交通感應(yīng)系統(tǒng)是一種具有調(diào)整交通信號(hào)設(shè)置來測(cè)量交通量的能力的先進(jìn)彈性連續(xù)性系統(tǒng)。</p><p>　　在車流量大或車速高的道路動(dòng)脈一定被流量和車速相對(duì)較輕的交叉路所中斷處，半觸動(dòng)式交通信號(hào)有

83、時(shí)被使用。對(duì)于它們，探測(cè)器僅被布置在次要街道。正常的信號(hào)指示是在主路的綠燈和十字街道的紅燈。關(guān)于此裝置，當(dāng)它們變回原來的顏色，指示經(jīng)過一個(gè)適當(dāng)?shù)臅r(shí)間間隔變得相反。</p><p>　　摘自：克拉克森H.奧格爾斯比和R.加里.?？怂埂豆饭こ獭?，1982</p><p>　　Highway Capacity And Levels of Service</p><p>

84、　　Capacity Defined</p><p>　　A generalized definition of capacity is: The capacity of any element of the highway system is the maximum number of vehicles which has a reasonable expectation of passing over t

85、hat section (in either one or both directions) during a given time period under prevailing roadway and traffic conditions. A sampling of capacities for modern highway elements is as follows:</p><p>　　In tre

86、ating capacity，TRB Circular 212 divides freeways into components: basic freeway segments and those in the zone of influence of weaving areas and ramp junctions. Capacities of expressways，multilane highways，and two- and t

87、hree-lane facilities also have the two components: basic and those in the zone of influence of intersections. Each of these is treated separately below.</p><p>　　Speed-Volume-Capacity Relationships for Basic

88、</p><p>　　Freeway and Multilane Highway Segments</p><p>　　A knowledge of the relationships among speed，volume，and capacity is basic to understanding the place of capacity in highway design and o

89、peration. Figurel3.1，which gives such a relationship for a single freeway or expressway lane, is used for illustrative purposes.</p><p>　　If a lone vehicle travels along a traffic lane，the driver is free to

90、proceed at the design speed. This situation is represented at the beginning of the appropriate curve at the upper left of Fig. 13.1. But as the number of vehicles in the lane increases, the driver's freedom to selec

91、t speed is restricted. This restriction brings a progressive reduction in speed. For example，many observations have shown that，for a highway designed for 70 mph (113km/h)，when volume reaches 1900 passenger cars pe</

92、p><p>　　Effects of the imposition of speed limits of 60, 50, and 40 mph are suggested by the dotted lines on Fig. 13. 1. A 55-mph (88km/h) curve could also be drawn midway between the 60 and 50 mph dotted curv

93、es to reflect the effects of the federally imposed 55-mph limit, but this is conjectural since the level of enforcement varies so widely.</p><p>　　Vehicle spacing，or its reciprocal, traffic density, probably

94、 have the greatest effect on capacity since it generates the driver's feeling of freedom or constraint more than any other factor. Studies of drivers as they follow other vehicles indicate that the time required to r

95、each a potential collision point，rather than vehicle separation，seems to control behavior. However，this time varies widely among drivers and situations. Field observations have recorded headways (time between vehicles)

96、rang</p><p>　　The ‘Level of Service’ Concept</p><p>　　As indicated in the discussion of the relationships of speed, volume or density, and vehicle spacing, operating speed goes down and driver r

97、estrictions become greater as traffic volume increase. ‘Level of service’ is commonly accepted as a measure of the restrictive effects of increased volume. Each segment of roadway can be rated at an appropriate level，A

98、to F inclusive，to reflect its condition at the given demand or service volume. Level A represents almost ideal conditions; Level E is at cap</p><p>　　The two best measures for level of service for uninterrup