成本上升因素现象的分类

《成本上升因素现象的分类》由会员分享，可在线阅读，更多相关《成本上升因素现象的分类（7页珍藏版）》请在装配图网上搜索。

1、施工项目成本上升成本上升因素现象的分类分析认为，从过去的三角剖分方法研究和访谈中，创建一个成本上升的 原因分类，可以更好地理解到成本上升因素，是通过每个因素或因素的根源的推 动力引起的。有了这样的认识，就能设计出策略来处理这些成本上升问题。在每 个项目开发阶段的影响因素，主要分为内部因素和外部因素。导致成本上升和控 制机构或业主内部的因素是直接控制现有的外机构或所有者分类外部的因素。演 示顺序的因素，不应被视为暗示的影响。它总结成逻辑分区和分类汇总的因素并 有助于在可视化的项目成本估算受到影响。需要重点注意的是，其中的因素指明 与估计的劳动力和原材料成本的因素有关，但最值得注意的是其影响项目的

2、范围 和时机。内部因素内部因素是成本上升的主要因素，可直接被项目的赞助机构或所有者所控制。虽 然许多内部因素成本在规划和设计阶段，可能会导致项目低估。主要的内部七大 因素是有据可查的：偏差，交付/采购方式，项目进度的变化，工程和建筑的复 杂性，范围的变化，范围逐渐扩大，贫困人口估计交配，此外，还有突发事件的 不一致的应用程序的问题。一个项目的成本上升不只发生在规划和设计阶段，项 目成本增长往往体现在施工期间。聚焦早期，内部因素会降低成本增长投标时间 或减少在2006年期间建设安达等人。内部原因导致这种项目执行过程中低估成 本，是工程项目管理不善造成的，这种文档设计是有缺陷的。更多的分析显示这

3、些因素包括不应用权变，错误的执行，含糊不清的合同规定，以及合同文件冲突。 每个这些因素单独或与他人相结合，可能会导致显著着的项目成本随着时间的推 移而增加。偏差是证明系统的倾向过于乐观的重点项目参数。它通常被视为故意低估项 目成本，确保项目仍然在建设规划中。这种低估成本可能会出现的估计鉴定与机 构或室的目标，保持施工方案。它可以是一种骄傲的结果，一种认为我们的机构 比那些有问题的人更聪明的感觉。不会屈从于问题变化的范围，范围逐渐扩大， 估算不佳，或任何其他因素。项目开发过程中，一些政府机构，立法机关的立法 行为，建立了工程预算，预算是根据初步成本估算的。后来，如果执行机构的估 计是高于项目预算

4、的，这个项目就不能通过。因此，工程师和机构感到了压力， 就以一种乐观的态度来估计了。例如1998年的阿肯哲和菲舍尔等。1998年康 登和哈曼，1970年的Hufschmidt和日兰。送货或采购方式影响了机构或雇主和建设人员的风险划分，而当风险转移 到一个谁也无法控制的特定风险时，项目的成本可能会增加。有关决定哪些项目 的交付方式，如设计-招标-建造，设计，建设，或建立经营-转让和采购方 法，如，低价中标，最佳值，或资格的选择会影响转让项目的风险。除了风险分 配的问题，缺乏经验与交付方式或采购方式也导致低估项目成本。许多机构和业 主正在寻求降低项目的时间表，以提供更多需要加速的项目需求，但加速时

5、间表 的实现是要代价的。虽然最终结果采用不同的采购的方法应该是有利的，但是一 些沉痛的教训也应该适当的分配，风险和每一个新的的承包方法都需要机构或业 主的响应、期望。外部因素外部成本上升的因素，机构或所有者对这些因素的影响已经很少甚至没有直接控 制。然而，在估算项目成本时，仍需要考虑他们。在项目发展的规划和设计阶段 中的外部因素，如当地政府关注和需求，扰动的速度信息，范围变更，范围逐渐 扩大，以及市场条件可能会导致项目成本的低估。在项目建设过程中的外部因素, 如当地政府的关注和需求，市场条件，不可预见的事件，和不可预见的条件都会 造成项目成本的增加。对于此类可能性事件必须做好估计的考虑。再次必

6、须认识 到，这些元素中的每一个可以单独地或组合地采取行动都会造成重大项目的成本 增加。当地的关切和要求通常包括缓解对周围社区以及协商范围变更或新增项目 的影响。机构/所有者往往需要减轻对当地的社会环境，以及自然环境有负面影 响的建设项目。措施可包括项目设计，走线，及进行施工作业。这些步骤往往采 取安抚当地的居民，企业主，和环保团体等手段。在早期往往是未知的所需的住 宿项目开发阶段。有许多采用“激烈”措施的例子，以适应当地的政府与公民关系 以及民族关系。最显著的两个例子是旧高速公路工程在犹他州和马萨诸塞州的大 挖掘。未知的土壤条件会影响开挖、压实、基础结构，受污染的土壤也会出现， 现在的实用程序

7、有很多问题，一般出现在错误的描述或者描述错误的图纸中，只 不过这项技术还在规划和设计阶段，不过它也会显著增加项目成本。市场条件下 的宏观环境的变化会影响一个项目的成本，尤其是大型工程项目。通常只有大型 承包商或承建商组可以进行大型工作，甚至获得一个大型项目的键合。一个项目 的规模会影响该项目和机构/所有者接收工作的投标数量的竞争。通常情况下， 大项目得风险要大得多，无论是对业主还是承包商，这些都会影响项目成本。 市场的不准确的评估会导致不正确的项目成本估算。市场条件在执行阶段和规划 阶段对项目成本都会有类似的影响。不可预见的事件是无法预料到的，而且通常 是不能由项目业主控制的，这可能是一个事件

8、，例如oods，飓风，龙卷风或其 他天气相关的事件。通常，这些事件被称为“上帝的行为”，这些行为会带来建设 停滞，已经遭遇到的一些工作销毁，造成了需要大量的返工或维修。由第三方进 行的活动控制也是不可预见的，包括恐怖袭击，罢工，和金融或商品市场的变化， 这些行动将会造成项目和项目成本的严重性破坏。Construction Project Cost Escalation FactorsJennifer S. Shane, A. M. ASCE1; Keith R. Molenaar, M.ASCE2; Stuart Anderson, M.ASCE3; andCliff Sc hexnayder

9、, Dist.M.ASCECost Escalation Facto r ClassicationThe t riangulat ion analy sis considered met hodologies from p ast studies and int erviews t o creat e a cat egoriz ation for t he causes ofcost escalat ion. A bett er underst anding of t he cost escalat ion fac - tors is achieved through underst andi

10、ng t he forces driving each fact or or where t he fact or originat es. Wit h this underst anding it is p ossible to design st rat egies for dealing w ith these cost escalat ion factors.The factors t hat affect t he est imate in each project develop - ment phase are by nat ure int ernal and ext ernal

11、. Fact ors t hat con - t ribut e to cost escalat ion and are cont rollable by t he agency /owner are int ernal, while fact ors exist ing out side the direct cont rol of t he agency /owner are classied as ext ernal. T his arrangement of fac - tors is shown in T able 2. T he present ation order of t h

12、e fact ors should not be t aken as suggest ing a level of inuence. T able 2 is const ruct ed t o provide an over arching summary of t he fact ors. It summariz es t he fact ors int o logical divisions and classicat ions and help s in visualiz ing how project cost est imat es are affect ed. It is imp

13、ort ant to not e that one of the factors p oint s to p roblems wit h est imat ion of labor and mat erial cost , but most of t he fact ors p oint to “ inuences” t hat imp act p roject scop e and t iming.InternalInt ernal factors are cost escalat ion factors t hat can be direct ly cont rolled by the p

14、 roject s sp onsoring agency /owner. While nu - merous int ernal fact ors can lead t o underest imat ion of project costs during t he p lanning and design st ages of develop ment seven p rimary int ernal fact ors are well document ed: bias, delivery / p rocurement app roach, project schedule changes

15、, engineering and const ruct ion comp lexit ies, scop e changes, scop e creep , poor est i- mat ing, and addit ionally there is t he issue of inconsist ent app li- cat ion of cont ingencies. Cost escalat ion does not only occur during t he p lanning and design p hases of a p roject. Project cost gro

16、wt h oft en manifest s it self during const ruct ion. Focusing early on int ernal factors will reduce cost growt h at bid t ime or during const ruct ion Anderson et al. 2006 . Int ernal fact ors that lead t o the underest imat ion of p roject cost s during t he execut ion o f a p roject st em from p

17、 oor p roject management and defect ive design document s. More sp ecically , these fact ors can include inconsis - tent app licat ion of cont ingency , faulty execut ion, ambiguous con - tract provisions, and cont ract document conicts. Each of t hese fact ors sep arat ely or in combinat ion wit h

18、others can cause signi - cant p roject cost s increases over t ime.Bias is t he demonst rated syst emat ic t endency to be overopt i- mist ic about key p roject p aramet ers. It is oft en viewed as t he p urposeful underest imat ion of project costs t o ensure a p roject remains in t he const ruct i

19、on p rogram. T his underest imat ion of costs can arise from t he est imat ors ident icat ion wit h the agen - cys or rms goals for maint aining a const ruct ion p rogram. It can also be t he result of pride and a feeling t hat our agency is smart er than t hose others t hat had p roblems and will n

20、ot succumb t o the issues of scop e changes, scop e creep , p oor est imat ing, or any of the ot her fact ors.The p roject develop ment p rocess for some governmentagen -cies is such t hat the legislat ure est ablishes a p roject budget by legislat ive act and t hat budget is based on p reliminary c

21、ost est i- mat es. Lat er, if the execut ing a genci es est imat e is higher t han the budget , the p roject cannot be let. As a result , engineers and agenc ies feel t he p ressure to est imat e wit h an opt imist ic att itude Akinci and Fischer 1998; Condon andHarman 2004; Hufschmidt and Gerin 197

22、0;Pickrell 1992 .Delivery /p rocurement app roach effects t he division of risk be - tween the agency /owner and t he const ruct ors, and when risk is shift ed t o a p arty who is unable to cont rol a sp ecic risk, project cost will likely increase. T he decision regarding which p roject delivery ap

23、p roach, e.g., design -bid-build, design-build, or buildop erat e-t ransfer and p rocurement met hodology e.g., low bid, best value, or qualicat ions based select ion affects t he t ransfer of p roject risks. In addit ion t o the quest ion of risk allocat ion, lack of exp erience wit h a delivery me

24、t hod or procurement app roach can also lead t o underest imat ion of p roject costs. M any agencies and owners are looking t o reduce p roject schedules t o deliver much - needed p roject s quickly but accelerat ed schedules are only achievable at a cost. While t he end result s of app lying differ

25、ent p rocurement app roaches should be benecial, some hard lessons have been learned regardin g the p rop er allocat ion of risks and what each new cont ract ing met hod ent ails, in t erms of agency / owner resp onsiveness, exp ect at ions, and t ime Harbuck 2004;New Jersey Dep art ment of T ransp

26、ort at ion 1999; Parsons Brinck-erhoff Quade & Douglas, Inc. 2002; Science App licat ions Int er- nat ional Corp orat ion 2002; Weiss 2000 .Project schedule changes, p art icularly ext ensions, caused by budget const raints or design challen ges can cause unant icip ated increases in inat ion cost e

27、ffect s even when t he rat e of inat ion is accurat ely p redict ed. Agencies/owners mustthink in t erms of t hetime value of money and recogniz e t hat there are t wo comp onents to the issue: 1 t he inat ion rat e and 2 t he t iming of t he exp en- dit ures. Many agencies and owners have xed annua

28、l or biannual budget s and p roject schedules must oft en be adjust ed t o ensure that p roject funding is available for all p rojects as needed. Est i- mat ors frequent ly do not know what exp endit ure t iming adjust -ment s will be made Board on Infrast ruct ure and t he Const ruct ed Environment

29、 2003; Booz Allen & Ha milt on Inc. and DRI/ M cGraw-Hill 1995; Callahan 1998; Hufschmidtand Gerin 1970;GAO 1999; Semp le et al. 1994; T ouran et al. 1994 .Engineer ing and const ruct ion comp le xit ies caused by the p roject s locat ion or purp ose can make early design work very challen ging and

30、lead t o int ernal coordinat ion p roblems and p roject comp onent errors. Int ernal coordinat ion p roblems can in - clude conict s or p roblems bet ween t he various discip lines in - volved in t he p lanning and design of a p roject. Const ruct ability p roblems t hat need t o be addressed may al

31、so be encount ered as the p roject develop s. If these issues are not addressed app ropri - ately , cost increases are likely to occur Board 2003; T he Big Dig: Key fact s about cost , scop e, schedule, and manage ment 2003; Booz Allen & Hamilt on Inc. and DRI/McGraw-Hill 1995; Callahan 1998; GAO 20

32、03; Hufschmidt and Gerin 1970; GAO 1997, 1999, 2002; T ouran et al. 1994 .Scop e changes, which should be cont rollable by the agent / owner management , can result in underest imat ion of p roject cost s. Such changes may include modic at ions in project con - st ruct ion limits, alt erat ions in d

33、esign and/or dimensions of key p roject it ems such as adjust ments in typ e, siz e, or locat ion of p roject comp onent s, as well as ot her increases in p roject elements Board on Infrast ruct ure and t he Const ruct ed Environment 2003; Booz Allen & Hamilt on Inc. and DRI/McGraw-Hill 1995; Callah

34、an 1998; Chan g 2002; Harbu ck 2004; Hufschmidt and Gerin 1970; M ackie and Prest on 1998; GAO 1999; M errow 1988;Semp le et al. 1994; T ouran et al. 1994 .Scop e creep is t he t endency for t he accumulat ion of many minor scop e changes t o increase p roject cost s. While individual scop e changes

35、 may have only minimal cost imp acts, t he accumu - lat ion of t hese minor changes, which are oft en not essent ial to t he int ended funct ion of t he facility , can result in a signicant cost increase over t ime. M any of t hese minor changes are real ne eds that are recogniz ed as more is known

36、about the p roject but ot hers are oft en only nonessent ial addit ions. Projects oft en seem t o grow nat urally as t he p roject p rogresses from incept ion t hrough design develop ment to const ruct ion. T hese changes can oft en be att rib- uted t o the different needs of t he traveling p ublic

37、or environmen - tal comp liance in t he area being served Akinci and Fischer 1998;Board on Infrast ruct ure and t he Const ruct ed Environment 2003; Booz Allen & Hamilt on Inc. and DRI/McGraw-Hill 1995; Callahan 1998; Chan g 2002; Harbu ck 2004; Hufschmidt and Gerin 1970; M ackie and Prest on 1998;

38、GAO 1999; M errow 1988;Semp le et al. 1994; T ouran et al. 1994 .Poor est imat ing can lead t o p roject cost underest imat ion. Es - timat e document ation must be in a form t hat can be underst ood, checked, veried, and correct ed. T he foundat ion of a good est i- mat e is t he formats, p rocedur

39、es, and p rocesses used t o arrive at the cost. Poor est imat ion includes general errors and omissions from p lans and quant ities as well as gener al inadequ acies and poor p erformance in p lanning and est imat ing p rocedures and t echniques. Errors can be made not only in t he volume of mat eri

40、al and services needed for p roject comp let ion but also in the costs of acquiring such resources Ardit i et al. 1985; Booz Allen & Hamilton Inc. and DRI/M cGraw -Hill 19 95; Ch ang 2002 ; Harbuck 2004; Hufschmidt and Gerin 1970; M errow 1988; Pickrell 1992 . Inconsist ent app licat ion of cont ing

41、encies causes confusion as to exact ly what is included in t he line it ems o f an est imat e and what is covered by cont ingency amount s. Cont ingency funds are typ ically meant to cover a variety of p ossible event s and problems that are not sp ecically ident ied or t o account for a lack of p r

42、oject denit ion during t he p rep arat ion of early p lanning or p ro- gramm ing est imat es. M isuse and failure t o dene what costs con - t ingency amount s cover can lead t o est imat e p roblems. In many cases it is assumed t hat cont ingency amount s can be used t o cover added scop e and p lan

43、ners seem t o forget that the p urp ose of the cont ingency amount in t he est imat e is t o cover lack of design denit ion. Agencies and owners run int o p roblems when t he con - t ingency amount s are app lied inapp rop riat ely. Inconsist ent app li- cat ion of cont ingency can be bot h an int e

44、rnal fac tor cont ribut ing to underest imat ion during t he p lanning and p reliminary design st age and a cont ribut or t o cost overruns during nal desi gn or const ruct ion phases of the p roject. During project construct ion, cont ingency funds are inapp rop riat ely app lied t o c onst ruct io

45、n overruns and t hen not available for t heir int ended p urp ose Noor and T ichacek 2004; Rip ley 2004 .Faulty execut ion by an agency /owner in managing a p roject is one fact or t hat can lead t o project cost overruns. T his fact or can include t he inabili ty of t he agency s/owners rep resent

46、at ives t o make t imely decisions or act ions, t o p rovide informat ion relat ive to the p roject , and failure t o app reciat e const ruct ion difcult ies caused by coordinat ion of connect ing work or work resp onsibili - ties Board on Infrast ruct ure and t he Const ruct ed Environment 2003; Ca

47、llahan 1998; Chan g 2002; T ouran et al. 1994 .Ambiguous contract prov isions dilut e resp onsibility and cause misunderst anding bet ween an owner and p roject design and con - st ruct ion cont ract ors. Providin g too litt le informat ion in t he p roject documents can lead to cost overruns during

48、 t he execut ion of t he project. When t he core assumpt ions underly ing an est imat e are confused by ambiguous cont ract provisions forecast accuracy cannot be achieved Call ahan 19 98; Chan g 2002; Harbuck 2004;M ackie and Prest on 1998; T ouran et al. 1994 .Cont ract document conicts lead t o e

49、rrors and confusion while bidding and lat er during p roject execut ion t hey cause change or - ders and rework Call ahan 1998; Ch ang 2002; Harbuck 200 4; M ackie and Prest on 1998; T ouran et al. 1994 .ExternalExt ernal cost escalat ion fact ors are those fact ors over which t he agency /owner has

50、 litt le or no direct cont rol over their imp act. However, t he agency /owner needs t o consider t hem when est i- mat ing p roject costs. During t he p lanning and desi gn p hase of p roject develop ment ext ernal fact ors such as local government concerns and requirement s, uct uat ions in t he r

51、at e of inat ion, scop e change, scop e creep , and market condit ions can lead t o underest imat ion of p roject costs. During p roject const ruct ion ext ernal fact ors such as local govern ment concerns and require - ment s, market condit ions, unforeseen event s, and unforeseen condit ions can b

52、e resp onsible for increases in p roject cost. T he p ossibility of such incident s must be considered during est imat e p rep arat ion. Again it must be recogniz ed t hat each of t hese ele - ment s can act sep arat ely or in combinat ion with ot hers t o cause signicant p roject cost increases.Loc

53、al concerns and requirement s typ ically includ e mit igat ion of p roject imp acts on t he surrounding community as well as ne - got iat ed scop e changes or addit ions. Act ions by the agency /owner are oft en required t o alleviat e p erceived negat ive imp acts of con - st ruct ion on t he local

54、 societ al environment as w ell as t he nat ural environment. M easures may include but are not limit ed t o int ro - ducing changes t o p roject design, alignment , and t he conduct of const ruct ion op erat ions. T hese st eps are oft en t aken to app ease the local residents, business owners, and

55、 env ironment al groups. The required accommodat ion is oft en unknown during t he early st ages of p roject develop ment. T here are a mult itude of examp les of “ drast ic” measures that are t aken t o accommodat e local gov - ernment and cit izen concerns as well as nat ional concerns with two of

56、 t he most not able e xamp les bein g act ions durin g the Legacy Highway p roject in Ut ah and t he Big Dig in M assachu - sett s In Ut ah environment concerns raised by the community p lay ed a major role in delaying t he project and increasing t hecost. In M assachusett s t he communit y demanded

57、 a si gnat ure bridge across t he Charles River. The result ing cable -st ayed bridge wit h Y-shap ed t owers added signicant ly to the project s cost. Local Concerns and Requirement s can affect p roject cost s dur - ing t he execut ion p hase. Similar t o the effects during t he p lanning and desi

58、gn p hases, mit igat ion act ions imp osed by the local gov - ernment , neighborhoods, and businesses as well as local and na - t ional environment al group s during t he const ruct ion of a p roject can ext end t he p roject durat ion affect ing inat ion allowances or add direct cost. By not ant ic

59、ip ating t hese changes, agen cies/ owners can be p lagued by p roject cost increases Board on Infra - st ruct ure and t he Const ruct ed Environment 2003; Booz Allen & Hamilt on Inc. and DRI /M cGraw -Hill 1995; C allah an 1998; Chan g 2002; Dani els 1998; H arbuck 20 04; Huda chko 2004 ; “Lega cy

60、Parkway : Hist ory of t he Legacy Parkway.” 2004;M ackie and Prest on 1998; GAO 1999; M errow 1988; Parsons Brinckerhoff Quade & Douglas, Inc. 2002; Pea rl 1994; Sawy er 1952; Schroeder 2000; “ Summ ary of indep endent review commit - tee ndings re gardin g Woodrow W ilson Brid ge sup erst ruct ure

61、cont ract ” 2002; T ouran et al. 1992 1994; Woodrow Wilson Bridge p roject sup erst rucy ure cont ract BR -3 : Review of t he engin eers est imat e vs. t he single bid 2002 .Effect s of inat ion is a key fact or in the underest imat ion of costs for many project s. The t ime value of money can adver

62、sely affect p rojects when 1 p roject est imat es are not communicat ed in y ear-of-const ruct ion costs , 2 p roject comp let ion is delay ed and therefore t he cost is subject to inat ion over a longer durat ion than ant icip ated, and/or 3 the rat e of inat ion is great er t han ant icip ated in

63、t he est imat e. Indust ry has vary ing views regarding how inat ion should be account ed for in p roject est imat es and in budget s. In t he case of p rojects wit h short develop ment and con - st ruct ion schedules, t he effect of inat ion is usually minor; how - ever p roject s having long devel

64、op ment and const ruct ion durat ions can encount er unant icip ated inat ionary effects. T he cost est i- mat es for t he Big Dig in Bost on are an exa mple of inat ion ef - fect s. T he Big Dig est imat e was originally develop ed in 1982 based on t he Federal Highway Administ rat ion guidelines s

65、t ated in the Int erst ate Cost Est imat e manual. T he p rocedures called for the exclusion of inat ionary fact ors. Inat ion is a large p ort ion of t he cost overruns exp erienced on t he p roject Akinci and Fischer 1998; Ardit i et al. 1985; Board on Infrast ruct ure and t he Con - st ruct ed En

66、vironment 2003 ; Booz Allen & Hamilt on Inc. and DRI/M cGraw -Hill 1995; Hufschmidt and Gerin 1970; M errow 1988; Pickrell 1992; T ouran et al. 1994 .Scope chang es, which are not cont rollable by t he owner, canlead t o underest imat ion of p roject cost escalat ion. In Californi a the new east sp an bridge bet ween Oakland and Yerba Buena Is - land was t he resp onsibility