快遞運(yùn)輸外文翻譯---基于車隊(duì)調(diào)度的特點(diǎn)分析快遞服務(wù)的網(wǎng)絡(luò)設(shè)計(jì)

1、<p>　　Enriching the tactical network design of express service carriers with fleet scheduling characteristics</p><p>　　W. J. M. Meuffels ? H. A. Fleuren ?F. C. A. M. Cruijssen ? E. R. van Dam</p>

2、<p>　　1 Introduction</p><p>　　Express service carriers provide time-guaranteed deliveries of parcels. Direct transport from sender to receiver is the fastest way of transport but this is in general not

3、 cost efficient. Therefore, express carriers operate a network in which parcels of many customers are consolidated. Parcels of several senders are consolidated at nodes (in practice called depots, terminals, etc.), trans

4、ported to other nodes via the line-haul network and finally delivered to the consignees. We will now briefly </p><p>　　The first node at which a parcel arrives after pickup is called the origin node (or orig

5、in) of the parcel; the node from where the parcel is delivered to the consignee is called the destination node (or destination) of the parcel. The transport of parcels between origin node and destination node is called l

6、ine-haul. Origin and destination node form an od-pair. Cut off times form the connection between the pickup and delivery process and the line-haul process and guarantee the on-time delivery of</p><p>　　That

7、is, all parcels of one service collected in the pickup process have to be processed and loaded into line-haul vehicles before the collection cut off time of the corresponding service; the line-haul transport starts after

8、wards. The line-haul vehicles have to arrive at the destination nodes before the delivery cut off time of the corresponding service. Carriers can use ground or air modes in their line-haul transport. Generally, road tran

9、sport is preferred because of the lower cost involved. </p><p>　　In general, strategic and tactical network design discussed in the literature focus on minimisation of the sum of unit transport cost. It is g

10、enerally assumed that consolidated transport between hub locations benefits from economies of scale such that unit transport cost of inter-hub flows can be discounted. The main restrictions in both strategic and tactical

11、 network design are flow conservation and service commitment. Flow conservation requires that all flow has to be transported between nodes</p><p>　　The first extension on the existing literature concerns the

12、 cost function, which in practice turns out to be more complex than generally seen in the literature. In the latter, the cost function results from unit transport cost and inter-hub transport is discounted. However, O’Ke

13、lly and Bryan (1998) claim that the inclusion of an exogenously determined discount applied to all inter-hub arcs regardless of the differences in the flows travelling across them, oversimplifies the problem. The authors

14、 </p><p>　　The cost in our network design incorporates the plainly linear cost function, since we explicitly determine vehicle movements. This approach is applied to all arcs in the network, so it is not lim

15、ited to inter-hub arcs only. The discounting of only interhub arcs was also questioned by Podnar et al. Besides, we improve the reflection of real-world cost made by express carriers by the inclusion of some other cost c

16、omponents. One of these is vehicle balancing cost. Crainic (2002) describes the need</p><p>　　It should be noted that (some of) the cost aspects discussed above are captured in the literature on design of ai

17、r networks. However, to the best of our knowledge, no literature on the design of road networks has included these cost components in their modelling. Express carriers offering next day services face tight time constrain

18、ts. The literature discusses the usage of a cover radius (Kara and Tansel 2003), which is a bound on transport time. However, the available time to transport flows dep</p><p>　　2 Related literature</p>

19、<p>　　This section briefly discusses the literature on the hub network design problem. Recent overviews on hub network design in express networks are given by Alumur and Kara (2009). Overviews on hub network desig

20、n in general are given by ReVelle et al. (2008) and Melo et al. (2009). Kuby and Gray (1993) consider the tactical network design in air transport examining tradeoffs and savings involved with stopovers and feeders towar

21、ds a single air hub location. The authors observed that in real-world pra</p><p>　　The tactical hub network design in air transport is further examined by Barnhart and Schneur (1996). Pick up and delivery ai

22、rcraft routes and schedules are derived towards a single hub node. Each aircraft route begins at the hub, visits a set of destination nodes followed by an idle period, then visits a set of origin nodes before returning t

23、o the hub. A system that determines aircraft routes, fleet assignments and package routings simultaneously has been described by Armacost et al. (2004). Lik</p><p>　　Lin and Chen (2008) considers the integra

24、tion of flow routing and fleet scheduling in a network which may contain stopovers and directs. Cost components taken into account are fixed fleet cost, fleet transportation cost, balancing cost, and location handling co

25、st. Again, fleet routes are derived and each such route can be performed by one vehicle or aircraft. Compared to their work in Lin and Chen (2004), no clustering operation is performed although the model will still assig

26、n a node location t</p><p>　　3 Modelling</p><p>　　The modelling presented in this section solves the network design and fleet scheduling problem in two steps. First, a tactical network design mo

27、del is run to derive flow routes. The tactical network design models that are used are discussed in Sect.3.1. Two models are proposed, the first model is a traditional model that discounts economies of scale on inter-hub

28、 flow routing, and will be used for benchmarking. The second model is new and includes fleet scheduling characteristics in network desig</p><p>　　This section discusses a traditional model of the tactical ne

29、twork design problem of an express provider. We call this model traditional since it reflects aspects that generally are incorporated in network designs seen in the literature (see Table 1). However, two aspects differ f

30、rom traditional models, namely service commitment and the node-hub assignment. We chose to satisfy the service commitment constraint here, since service commitment has highest priority in the express business, and netwo&

31、lt;/p><p>　　Instead of incorporating a scaling factor for economies of scales, an upper bound on economies of scales can be obtained by determining the minimum number of vehicles required to transport the flows

32、. This network design model selects a route for each service of an od-pair; the routes that can be selected need to satisfy the service requirements of the corresponding service of the od-pair. Since each chosen route is

33、 feasible, the model results in a minimum number of vehicles to transport the flow</p><p>　　The heuristic uses an event list E of possible departures. All flow is assumed to be available at the origin node a

34、t the collection cut off time. These collection cut off</p><p>　　times cis o are the first possible departure times that are added to the event list. The second group of possible departure times that are add

35、ed are the so-called critical departure times. All flow has to be available at the destination node before the delivery cut off time of its corresponding service. The latest departure time of od-service i, j, s at locati

36、on sa of arc a is called the critical departure time, denoted by tijsa crit. The last group of events, the availability time of flow at hu</p><p>　　The heuristic starts with the first event time e in the eve

37、nt list. Then it checks: (1) do there exist arcs with flow having reached a critical departure time? If there is some flow, vehicles are scheduled to depart and the flow is transported. If there is none, the next questio

38、n is: (2) do there exist arcs for which all flow has arrived? If there exists such an arc, vehicles are scheduled and flows are transported to the next location. Finally, it is checked: (3) do there exist arcs at which a

39、 </p><p>　　Cut off times are used to determine the available time to transport flows in the network design models. However, the moment of transport is not taken into account (i.e. the possibility to combine

40、flows in time is not checked during network design). Note that including time moments in modelling flow routes would dramatically increase the number of routes possible, since no assumptions are made on departure moments

41、 at hub locations. Therefore, the fleet scheduling heuristic is run to estimate the </p><p>　　4 Conclusions and directions for further research</p><p>　　This paper proposed a new tactical networ

42、k design model for express carriers. The model was tested on modified instance data of an express carrier. Test cases were created for two geographies, and for each such geography three test cases were generated varying

43、in the geographical spread of demand. In each test case, cost savings could be achieved if routes proposed by the new network design were used instead of the traditional routes. The first geography showed an average cost

44、 saving of 5.0% and</p><p>　　Furthermore, the sensitivity analyses showed that the cost was 2.6 times as low when consolidation is used to transport flows compared to only direct driving. These savings can s

45、till be achieved even when only 60% of the hub capacity is available. Of all cost components, variable hub cost influences hub routing the most: Run Times 32 W.J.M. Meuffels et al. 123 increasing variable hub cost leads

46、to a strong decreasing hub routing. Higherbalancing cost leads only to a small increase in direct rout</p><p>　　Furthermore, it would be interesting to consider the network design of multiple countries at on

47、ce (e.g. the network design of Europe). We suggest a column generation approach to reduce computation time when scaling up to data instances of this size. Final fleet schedules were derived after flow routing. Further co

48、st reductions are expected if fleet schedules and flow routings are determined simultaneously. This article focused on the tactical network design of express carriers. More research ne</p><p>　　基于車隊(duì)調(diào)度的特點(diǎn)分析快

49、遞</p><p><b>　　服務(wù)的網(wǎng)絡(luò)設(shè)計(jì)</b></p><p>　　W. J. M. Meuffels ? H. A. Fleuren ?F. C. A. M. Cruijssen ? E. R. van Dam</p><p><b>　　1 引言</b></p><p>　　包裹快遞服務(wù)

50、運(yùn)營(yíng)商按時(shí)交貨，從發(fā)送方到接收者的直接運(yùn)輸是最快的運(yùn)輸方式，但這一般不符合成本效益。因此，快遞運(yùn)營(yíng)商在眾多包裹客戶建立網(wǎng)絡(luò)。一些包裹發(fā)送者集中在一個(gè)地點(diǎn)（比如倉(cāng)庫(kù)，碼頭等），通過(guò)長(zhǎng)途運(yùn)輸網(wǎng)絡(luò)運(yùn)到其他地點(diǎn)，并最終交付給收貨人?，F(xiàn)在，我們將簡(jiǎn)要介紹如何快速組織供應(yīng)鏈，然后通過(guò)對(duì)車隊(duì)調(diào)度的討論，描述出網(wǎng)絡(luò)設(shè)計(jì)，最后確定本文的研究目標(biāo)。</p><p>　　在包裹打包之后到達(dá)的第一個(gè)地點(diǎn)被稱為起源地點(diǎn)，交付收貨人的地點(diǎn)就

51、是所謂的包裹的目的地。起源點(diǎn)和目的地之間的包裹運(yùn)輸就是長(zhǎng)途運(yùn)輸，原產(chǎn)地和目的地形成一個(gè)網(wǎng)絡(luò)。需要切斷從打包到運(yùn)輸過(guò)程中的聯(lián)系以及長(zhǎng)途運(yùn)輸和準(zhǔn)時(shí)送達(dá)之間的聯(lián)系。也就是說(shuō)，在打包過(guò)程中把所有包裹集中在一次服務(wù)，之后在終止相關(guān)服務(wù)之前送達(dá)至長(zhǎng)途運(yùn)輸處，最后就是通過(guò)長(zhǎng)途運(yùn)輸在終止運(yùn)輸相關(guān)服務(wù)之前運(yùn)達(dá)目的地。運(yùn)營(yíng)商可以在他們的行長(zhǎng)途運(yùn)輸中使用地面或空中交通工具。一般來(lái)說(shuō)，鑒于較低的成本，公路運(yùn)輸是首選，。用于建立關(guān)系，航空運(yùn)輸是首選，地面運(yùn)輸則次

52、之。明確的說(shuō)，考慮成本，在航空網(wǎng)絡(luò)的設(shè)計(jì)中應(yīng)該著重考慮車隊(duì)的成本。在道路網(wǎng)絡(luò)，車隊(duì)的成本是一個(gè)重要的成本組成部分，但其他成本組成部分（如處理成本）也很重要，這些成本組成部分之間的權(quán)衡，決定了最終的網(wǎng)絡(luò)。</p><p>　　在一般情況下，在理論上重點(diǎn)討論減少戰(zhàn)略和戰(zhàn)術(shù)網(wǎng)絡(luò)設(shè)計(jì)單位運(yùn)輸成本。人們普遍認(rèn)為，綜合運(yùn)輸?shù)臉屑~位置經(jīng)濟(jì)和規(guī)模經(jīng)濟(jì)以致可以減少單位交通樞紐間流動(dòng)成本。在限制戰(zhàn)略和戰(zhàn)術(shù)網(wǎng)絡(luò)設(shè)上的成本就是流量保護(hù)和

53、服務(wù)協(xié)議。所有地點(diǎn)之間的運(yùn)輸流要暢通，服務(wù)協(xié)議就是在預(yù)定的時(shí)間范圍內(nèi)運(yùn)輸。戰(zhàn)術(shù)網(wǎng)絡(luò)設(shè)計(jì)后，車輛調(diào)度需要建立這樣的流動(dòng)程序，需要抓住車隊(duì)調(diào)度的一個(gè)重要方面輪候時(shí)間?，F(xiàn)有理論的第一個(gè)擴(kuò)展涉及的成本函數(shù)，在實(shí)踐中證明它比一般的理論更復(fù)雜。后者單位運(yùn)輸成本和樞紐間運(yùn)輸成本的貼現(xiàn)導(dǎo)致成本函數(shù)。然而，奧凱利和不冉燕（1998）聲稱包含一個(gè)外因決定的折扣運(yùn)用到所有跨樞紐運(yùn)輸不管在它們之間流動(dòng)的差額，過(guò)于簡(jiǎn)單化問(wèn)題。他又聲稱成本一定是非線性函數(shù)，非線性

54、成本函數(shù)近似是一個(gè)分段線性成本函數(shù)，其他成本降低造成流量增加。</p><p>　　在我們的網(wǎng)絡(luò)設(shè)計(jì)成本中包含線性成本函數(shù)，自從我們確定車輛運(yùn)輸。這種方法能應(yīng)用到網(wǎng)絡(luò)中的所有路線，所以它不局限于樞紐間的路線。只有樞紐路線貼現(xiàn)受到樸都那的質(zhì)疑。此外，我們提稿快遞運(yùn)營(yíng)商現(xiàn)實(shí)世界成本的映射，包括一些成本成分。其中一個(gè)就是平衡成本?？夏夏峥耍?002）描述了移動(dòng)空車輛的需要，因?yàn)樵谫Q(mào)易流動(dòng)中存在的不平衡，導(dǎo)致車輛的供應(yīng)和

55、需求在不同的區(qū)域之間存在一定的差異。應(yīng)當(dāng)指出上面討論的成本方面，在理論上的航空網(wǎng)絡(luò)設(shè)計(jì)獲得成功。然而，據(jù)我們所知，在理論上道路網(wǎng)絡(luò)設(shè)計(jì)的模型包括這些成本部分，快遞運(yùn)營(yíng)商提供次日服務(wù)面臨著緊迫的時(shí)間限制。文獻(xiàn)中討論了使用一個(gè)覆蓋半徑（卡拉和湯森2003），這是一個(gè)運(yùn)輸時(shí)間上的束縛。但是在有限的時(shí)間運(yùn)輸流量取決于服務(wù)定義，在本文中提出的戰(zhàn)術(shù)網(wǎng)絡(luò)設(shè)計(jì)模型采用減少時(shí)間而獲得運(yùn)輸?shù)目捎脮r(shí)間。這種方式可以包含多個(gè)服務(wù)，在網(wǎng)絡(luò)設(shè)計(jì)中，它不能確認(rèn)流動(dòng)是

56、否可以和一輛卡車相結(jié)合的，這是在運(yùn)行后的啟發(fā)。</p><p><b>　　2相關(guān)文獻(xiàn)</b></p><p>　　本節(jié)簡(jiǎn)要討論了文學(xué)上的樞紐網(wǎng)絡(luò)設(shè)計(jì)問(wèn)題，最近的快遞網(wǎng)絡(luò)的樞紐網(wǎng)絡(luò)設(shè)計(jì)概述由安姆和卡拉（2009）提出?？岜群突疑?993）考慮在航空運(yùn)輸研究權(quán)衡和中途停留和饋線對(duì)一個(gè)單一的航空樞紐位置的儲(chǔ)蓄戰(zhàn)術(shù)網(wǎng)絡(luò)設(shè)計(jì)。作者指出，對(duì)航空樞紐的直達(dá)航班，在現(xiàn)實(shí)世界中的做

57、法只是偶爾發(fā)生：大多數(shù)航班停在沿著自己的路線的幾個(gè)城市，并經(jīng)常與小型飛機(jī)在中等城市轉(zhuǎn)移負(fù)荷較大的飛機(jī)的支線。</p><p>　　戰(zhàn)術(shù)樞紐的航空運(yùn)輸網(wǎng)絡(luò)的設(shè)計(jì)是由巴恩哈特和斯涂特（1996）進(jìn)一步研究。拿起并正朝著一個(gè)單一的樞紐節(jié)點(diǎn)獲得交付飛機(jī)的航線和時(shí)間表。每架飛機(jī)的航線樞紐開(kāi)始，訪問(wèn)一組目的節(jié)點(diǎn)空閑時(shí)間，然后訪問(wèn)前一組起源節(jié)點(diǎn)返回到集線器。同時(shí)，確定飛機(jī)航線，船隊(duì)作業(yè)和包路線系統(tǒng)。像巴恩哈特（1996）一樣，

58、拿起和實(shí)現(xiàn)一個(gè)航空樞紐的運(yùn)送路線得到包括拿起和交付的時(shí)間窗，埃姆斯（2002）等人使用復(fù)合變量制訂解決類似的模型。林，陳（2008）認(rèn)為中途停留，并指出可能包含網(wǎng)絡(luò)流量路由和車隊(duì)調(diào)度的集成?？紤]成本組成部分是固定的成本艦隊(duì)，船隊(duì)運(yùn)輸成本，平衡成本，位置處理成本。再次，車隊(duì)路線得到，每個(gè)這樣的路線可以由一個(gè)車輛或飛機(jī)執(zhí)行。他們?cè)谂c林和陳（2004）的工作相比，沒(méi)有集群操作執(zhí)行，雖然該模型仍然會(huì)分配到一個(gè)集線器節(jié)點(diǎn)的位置。然而，為訪港操作使

59、用集線器可以不同于出境業(yè)務(wù)的樞紐，雖然所有入境（出境）流量將使用同樣的路線（從）的樞紐位置。樞紐各種連接問(wèn)題的處理，以滿足服務(wù)承諾，確定一個(gè)可行的車隊(duì)路線計(jì)劃和事后得到流動(dòng)路線。</p><p><b>　　3建模</b></p><p>　　在本節(jié)所介紹的建模兩個(gè)步驟解決了網(wǎng)絡(luò)設(shè)計(jì)和船隊(duì)調(diào)度問(wèn)題。首先，戰(zhàn)術(shù)網(wǎng)絡(luò)設(shè)計(jì)模型運(yùn)行，以獲得流動(dòng)路線。在教派的戰(zhàn)術(shù)所使用的網(wǎng)絡(luò)設(shè)

60、計(jì)模型進(jìn)行了討論。提出了兩個(gè)模型，第一種模式是傳統(tǒng)模式，折扣規(guī)模經(jīng)濟(jì)間樞紐流量路由，將用于為基準(zhǔn)。第二種模式是新的，包括網(wǎng)絡(luò)設(shè)計(jì)的船隊(duì)調(diào)度的特點(diǎn)。為了比較的結(jié)果，車隊(duì)調(diào)度的啟發(fā)式解決，以確定網(wǎng)絡(luò)的成本。</p><p>　　本節(jié)討論了網(wǎng)絡(luò)的戰(zhàn)術(shù)設(shè)計(jì)問(wèn)題，明確供應(yīng)商的傳統(tǒng)模式。我們稱這種模式傳統(tǒng)，因?yàn)樗从撤矫妫话阋?jiàn)于文獻(xiàn)的網(wǎng)絡(luò)設(shè)計(jì)中。然而，兩個(gè)方面不同于傳統(tǒng)的模式，即服務(wù)承諾和樞紐節(jié)點(diǎn)分配。我們選擇在這里，以滿

61、足服務(wù)承諾的約束，因?yàn)榉?wù)承諾的快遞業(yè)務(wù)中最高優(yōu)先級(jí)，網(wǎng)絡(luò)設(shè)計(jì)并不滿足這種限制是沒(méi)有快遞公司的價(jià)值。此外，也有新的網(wǎng)絡(luò)設(shè)計(jì)，以滿足這一要求，從而使只能在傳統(tǒng)模式中。如果這一要求也納入比較，并在很短的時(shí)間，以滿足服務(wù)，它并不總是可能只有一個(gè)集線器連接節(jié)點(diǎn)，因此，我們可以從節(jié)點(diǎn)到集線器的多個(gè)任務(wù)。</p><p>　　相反納入規(guī)模經(jīng)濟(jì)，規(guī)模經(jīng)濟(jì)的上限比例因子可以得到確定車輛運(yùn)輸流量所需的最低數(shù)量。這種網(wǎng)絡(luò)設(shè)計(jì)模型選擇

62、每一個(gè)網(wǎng)絡(luò)對(duì)服務(wù)的路線，可以選擇的路線，需要網(wǎng)絡(luò)對(duì)相應(yīng)的服務(wù)，以滿足服務(wù)需求。由于每個(gè)選擇的路線是可行的，這個(gè)模型導(dǎo)致車輛的最低數(shù)量的運(yùn)輸流。如果時(shí)間限制緊，需要更多的車輛運(yùn)輸流量。在寬松的時(shí)間限制的情況下，網(wǎng)絡(luò)設(shè)計(jì)模型確定的車輛數(shù)量可以滿足足夠的運(yùn)輸流。因此，該模型結(jié)果是實(shí)現(xiàn)經(jīng)濟(jì)規(guī)模的上限。啟發(fā)式的使用可能離開(kāi)的事件的清單。所有的流量被認(rèn)為是在收集的起源節(jié)點(diǎn)切斷時(shí)間。這些收集切斷數(shù)次是可能被添加到事件列表的出發(fā)時(shí)間。添加第二組出發(fā)時(shí)間

63、可能是所謂的關(guān)鍵起飛時(shí)間。所有的流量是在目標(biāo)節(jié)點(diǎn)交付之前切斷其相應(yīng)的服務(wù)時(shí)間。網(wǎng)絡(luò)服務(wù)的最新出發(fā)時(shí)間，一個(gè)弧形的位置被稱為關(guān)鍵的出發(fā)時(shí)間，記暴擊。最后一組的事件，在流的樞紐位置的可用時(shí)間，結(jié)果從車輛的到來(lái)：流在到達(dá)一個(gè)樞紐位置，需要進(jìn)一步的交通和運(yùn)輸是可能的后整理。</p><p>　　在抵達(dá)流量可以留下的樞紐位置的時(shí)間被稱為可用時(shí)間；J服務(wù)的可用性進(jìn)一步通過(guò)弧運(yùn)是無(wú)濟(jì)于事的。每車將啟程的時(shí)間，流量可運(yùn)。啟發(fā)式開(kāi)

64、始在事件列表中的第一個(gè)事件的時(shí)候發(fā)。然后檢查：（1）不存在與流量已達(dá)到一個(gè)關(guān)鍵的出發(fā)時(shí)間的弧線？如果有一些流動(dòng)，車輛預(yù)定離開(kāi)和運(yùn)輸流。如果沒(méi)有的，接下來(lái)的問(wèn)題是：（2）不存在所有流量已到達(dá)??？如果存在這樣一個(gè)弧形，車輛調(diào)度和流量輸送到下一個(gè)位置。最后，它被選中：（3）不存在一個(gè)完整的車輛可以裝載弧？如果是這樣的情況下，車輛離開(kāi)和流量在到達(dá)下一個(gè)位置。之后，e是從事件列表中刪除被認(rèn)為在事件列表中的下一個(gè)事件。啟發(fā)式終止時(shí)，所有的流量已抵達(dá)

65、其目的地節(jié)點(diǎn)。沒(méi)有確定車輛平衡成本，運(yùn)輸流量所需的車輛實(shí)數(shù)可以更高。因此，需要確定車輛平衡成本。</p><p>　　切斷時(shí)間用于確定可用的時(shí)間，運(yùn)輸網(wǎng)絡(luò)設(shè)計(jì)模型中的流動(dòng)。請(qǐng)注意，包括時(shí)間的時(shí)刻，在造型流路線，將大大增加路線可能，因?yàn)闆](méi)有假設(shè)出發(fā)時(shí)刻樞紐位置。因此，運(yùn)行車隊(duì)調(diào)度啟發(fā)式的可能性，結(jié)合流動(dòng)時(shí)間；如果不能結(jié)合流動(dòng)，其他車輛車隊(duì)調(diào)度的成本，一般比后發(fā)現(xiàn)網(wǎng)絡(luò)設(shè)計(jì)成本較高，但在成本上的差異取決于啟發(fā)式的路由。

66、因此，最理想的解決方案，網(wǎng)絡(luò)設(shè)計(jì)模型可以給更低的成本比最佳的解決方案，先網(wǎng)絡(luò)設(shè)計(jì)模型后車隊(duì)調(diào)度。</p><p>　　4結(jié)論和進(jìn)一步研究的方向</p><p>　　本文為運(yùn)營(yíng)商提出一個(gè)明確的新的戰(zhàn)術(shù)網(wǎng)絡(luò)設(shè)計(jì)模型，由快遞承運(yùn)商改進(jìn)的實(shí)例數(shù)據(jù)模型進(jìn)行了測(cè)試。測(cè)試是為兩個(gè)地域創(chuàng)建的，并為每個(gè)這樣的地域采用根據(jù)不同地理分布的需求進(jìn)行測(cè)試。在每個(gè)測(cè)試的情況下，如果使用新的網(wǎng)絡(luò)設(shè)計(jì)提出的路線替代傳統(tǒng)的

67、航線,可以達(dá)到節(jié)約成本的目的。第一個(gè)地理表明5.0％的平均節(jié)約成本和第二地理表明1.1％的平均節(jié)約成本。主要節(jié)約成本就是減少變量樞紐成本和平衡成本。</p><p>　　此外，靈敏度分析表明，成本低于2.6倍時(shí)，聯(lián)合運(yùn)輸與單個(gè)運(yùn)輸相比較，可以減少60％的樞紐能力。在所有成本部分，可變的樞紐運(yùn)輸主要影響樞紐運(yùn)輸路線，增加可變樞紐運(yùn)輸成本會(huì)大大增加樞紐運(yùn)輸路線。在直達(dá)路線中，最大程度的平衡成本只可小幅度飛增加路線，提

68、高運(yùn)輸成本導(dǎo)致小幅度增加樞紐路線。本文表明成本減少能帶來(lái)很大的好處，這些模型由兩個(gè)地形的改進(jìn)示例數(shù)據(jù)進(jìn)行測(cè)試，包括在快遞服務(wù)運(yùn)營(yíng)商的戰(zhàn)術(shù)網(wǎng)絡(luò)設(shè)計(jì)中的車隊(duì)時(shí)間表特征，地域之間的差異需要更進(jìn)一步的研究，分析得出地域的特征將影響快遞網(wǎng)絡(luò)路線。而且，此模型應(yīng)該立刻考慮到不同國(guó)家的網(wǎng)絡(luò)設(shè)計(jì)，比如歐洲的網(wǎng)絡(luò)設(shè)計(jì)。我們建議一方法去減少計(jì)算的時(shí)間當(dāng)對(duì)這個(gè)大小的示例數(shù)據(jù)按比例放大，最后的車隊(duì)時(shí)間表由行進(jìn)路線得到確認(rèn)。如果車隊(duì)時(shí)間表和路線可以同時(shí)決定，那就