[建筑]工程师估价量对单价合同的不准确影响中英文版.doc

工程师估价量对单价合同的不准确影响Abstract摘要：This paper discuss the issue of unbalanced bid prices in unit price highway contracts. 本文讨论了公路的合同单价的不平衡报价的价格问题。It analyzes the reasons contractors unbalance their bids and looks for ways that allow public transportation agencies to discourage this practice. 分析了原因，承建商竞投不平衡的方法，让公共交通机构，劝阻这种做法，并期待。It reviews the results of a study of quantity estimating accuracy of 462 transportation projects in Oklahoma, and finds that one method to reduce unbalanced bid prices is for the agency to ensure that the bid quantities used in the engineers estimate are as accurate as possible. 它审查的数量估计在俄克拉荷马州交通项目462个，准确的研究结果，发现了一个方法，以减少不平衡报价的价格是该机构，以确保中标，在工程师的估计使用量是尽可能准确。 Doing so reduces the need for contractors to unbalance to protect fixed costs and target profit on bid items that will underrun the quantity used in the engineers estimate.这样做减少了对不平衡保护承建商投标项目，将在欠载工程师的估计采用的数量固定费用和目标利润的需要。Dor:10.1061/(ASCE)CO.1943-7862.0000084 (ASCE的）有限公司 CE Database subject headings:Estimation;Pricing;Contracts;Highway and road construction. CE数据库主题词：估计;定价;合同;公路和道路建设。Background：背景The development of accurate pre-bid cost estimates is founded on the development of an accurate quantity estimate (UDOT 2007). 准确的投标前费用概算的发展是建立在一个准确的数量估算（UDOT 2007年）的发展。This is particularly true on unit price contracts where the competing construction contractors must bid the engineers estimated quantities even if they are incorrect (Schexnayder and Mayo 2004).这一点尤其对单价合同，即竞争性投标的建筑商必须工程师的估计数量，即使他们不正确（施克斯纳德和Mayo 2004）也是如此。There are two administrative factors that impact the accuracy of public engineers estimates. 有两个因素影响行政，公共工程的估计的准确性。First,most public agencies have constraints upon their ability to award construction projects based on the difference between the engineers estimate and the apparent low bid.首先，大部分公共机构后，其施工能力，奖励之间的工程师的估计以及差异明显偏低的出价为基础的项目的限制。For instance,the Utah Department of Transportation (DOT) requires the engineers estimate to be within 10% of the low bid (UDOT 2007).the Oklahoma DOT is historically refrains from awarding to bids that are more than 7% over the engineers estimate (ODOT 2008),and the U.S. Army Corps of Engineers (USACE) has more latitude but is nevertheless constrained by the low bid being no more than 15 and 25% over the independent government estimate for military and civil works projects,respectively (USACE) 1997. 例如，犹他州运输部（DOT）规定，工程师的估计将在10%低价中标（UDOT 2007）。俄克拉荷马DOT是历史上从颁发给出价超过工程师的估计的7%的约束下（ODOT 2008），以及美国陆军工程师（美国陆军工程兵团队）有更大的自由，但还是由低是不超过投标限制15和25%以上的军用和民用工程项目，分别为（美国陆军工程兵团）1997年独立的政府预算。Second,the issue is exacerbated by mandated maximum project contingency percentages,which limit the maximum amount of contingency that can be included in the agencys engineer estimates. 第二，加剧了该问题的应急计划规定的最高比例，限制最高数额的应急可在该机构的估计数包括工程师。For instance,USACE is limited to 5% contingency on new construction projects (USACE 1997) and Riverside County California cannot exceed 10% (Riverside County 1999). 例如，美国陆军工程兵团限制为5的应急新的建设项目（美国陆军工程兵团1997年）和加利福尼亚州里弗赛德县不能超过10（河滨县1999年）。The Utah DOT has more flexibility in setting its contingency on a project-by-project basis but,must justify contingencies greater than 10% on projects with completed designs.犹他点有一个项目在设置上按项目的基础上，但必须证明应急与完成的设计大于10的项目其应急更大的灵活性。The Washington DOT reported that the cost of highway construction was up 12.2% in April 2008 (WSDOT 2008a). 华盛顿报道，交通部公路建设成本同比2008年4月增长12.2（WSDOT 2008a）。So projects awarded in Riverside County with its 10% mandated contingency cap that month would be underestimated by roughly 2.2%.因此，在河滨县授予其授权的应急上限，10月将是低估了约2.2的项目。These two factors combine to create a tendency to inflate engineers estimates to ensure that needed infrastructure projects are awardable in periods of construction price volatility,and when the maximun contingency is reached, to inflate the estimated quantities as the only available avenue to increase the engineers estimate. 这两个因素结合起来，创造一种倾向，夸大工程师的估计来确保所需的基础设施项目的建造价格波动周期，并当具有极大相关应急到达，夸大为唯一可用的途径估计数量来提高工程师的估计。 This fact was confirmed in informal surveys conducted by the primary author during ASCE continuing education classes at 10 different DOTs. 这一事实证实了由主要作者进行非正式调查ASCE的过程中继续在10个不同的交通部教育课。When asked if quantities were ever inflated to increase project contingencies,at least one engineer in each class indicated that was a commom practice. 当被问及是否曾有充气量增加项目突发事件，至少在每一类工程师表示，这是一个蒲公英的做法。This practice is especially problematic in periods of extreme volatility such seen for asphalt prices,in the first two quarters of 2008(WSDOT 2008a). 这种做法，尤其是在2008年首两季（WSDOT 2008a）沥青价格大幅波动的时期内出现问题。The very structure of the unit price contracts pricing mechanism demands engineers estimated quantities be as accurate as possible to ensure the profitability of a balanced bid. 该单位的价格合同的定价机制，要求工程师的估计数量非常结构被认为是准确，最大限度地保证了均衡出价盈利能力。When actual quantities are less than the bid quantities,the contractor does not recover the fixed costs,overhead,and profit that were allocated to the quantities of work that were not installed and hence for which it cannot be paid. 当实际数量比中标数量少，承包者不收回固定成本，开销和利润被分配给那些没有工作的安装，因此它不能用于支付数量。Therefore,as most contractors have limited ability to pick and choose which projects they bid and remain in business,inaccurate bid quantities lead to unbalancing unit prices to recover all the costs associated with the project and to protect the contractors target profit on the bid. 因此，正如大多数承包商能力有限挑选哪些项目投标，并保持他们的业务，不准确的投标单位数量不平衡导致的价格收回所有与项目相关的成本，并保护承包人的出价的目标利润。The other side of that coin is the use of unbalancing to increase the contractors profit margin.它的另一面是不平衡，增加承包商的利润空间使用。The subject of unbalanced bidding is certainly controversial and the purpose of this paper is not to advocate or apologize for unbalanced bidding.不平衡的投标主体是一定争议，本文的目的不是要提倡或道歉不平衡报价。It is to advocate that the owners engineer resist the temptation to arbitrarily increase a projects bid quantities to create a hidden project contingency and demonstrate the potential impact of doing that in one typical public agency by an analysis of the accuracy of its estimating practices. 它是倡导，业主的工程师抗拒的诱惑，随意增加项目的投标数量，以创建一个隐蔽工程的应急和证明这样做的潜在影响，在一个典型的由一个做法，其估计精度分析公共机构。 Lump Sum Certainty:Ability to accurately survey the quantity of workCertainty Cost of Error:ImpactUnit Price of erroneous estimate at Time contract award. Cost Plus Cost of Error确定性：能够准确地调查工作的数量。成本误差：在签订合同时错误估计的影响。 一次性支付。 单位价格。 成本加。Fig.1. Contract type risk concept-quantity certainty versus cost of error图.1、契约型风险概念的确定性与数量的错误成本。Unit Price Contracting单价承包。“Unit price contracts are used for work where it is not possible to calculate the exact quantity of materials that will be required. Unit price contracts are commonly used for heavy/highway work” “优惠价合同用于工作的地方是无法计算的材料的具体数量，这将是必需的。单价合同通常用于重型/高速公路的工作。”(Schexnayder and Mayo 2004). （施克斯纳德和Mayo 2004年）。When an owner selects unit price contracting,it is doing so to share the risk of the final quantities of work with the contractor to reduce the price. 当业主选择单价承包，它这样做，分享与承包商降价工作的最后数量的风险。This happens because the contractor does not have to bid the worst possible case if the quantities of work are not finite as it would be driven to do in a lump sum contract where it bore the entire quantity risk. 这是因为承包商没有竞投最坏的情况下，如果工作中的数量是有限的，因为这将不被赶做一笔合同在这里孕育了整个数量的风险。Unfortunately,many owners do not understand the dynamics of unit price bidding and erroneously believe that by paying the contractor for every installed unit of work that they have covered the contractors total costs. 不幸的是，很多业主不理解单价投标的动态和错误地认为，通过支付各项工作，他们已经讨论了承包商的总成本安装单位承办。That only happens in a cost-plus contact where the owner bears the entire quantity risk. 这只会发生在成本加接触的业主承担全部数量的风险。Fig.1 shows the concept of when different types of contracting methods should be used based on the owners ability to accurately estimate the quantities of work. 图.1显示了在不同类型的承包方式，应采用基于业主能够准确地估计工作的数量概念。It shows that unit price contracts fall in the middle where neither the level of certainty nor the cost of an erroneous estimate is high. 结果表明，单价在合同中既不肯定也不是一个错误的估计成本高的水平下降。Thus,the risk is shared,and owners must recognize that the contractors major unit pricing contract risk is not getting to install the total amount of work upon which they must bid. 因此，风险是共同的，业主必须认识到承包者的主要单位定价合约的风险是没有得到安装工作后，他们必须投标总量。Before getting into the mechanics of the unbalanced bid,one must understand the fundamentals of developing a unit price for a given work item. 在深入的不平衡报价的机制得到，你必须理解为给定的开发工作项目单价的基础。Essentially,a unit price is the sum of all direct costs,allocated indirect costs and the contractors profit for a given item of work divided by the total number of units of work.从本质上讲，一个单位的价格是所有直接费用，间接费用分配和承包商的一个工作给予了工作单位的总数量除以项目的利润总和。This can be expressed as UP=(DC+IC+P)/N (1) 这可以表示为 UP=(DC+IC+P)/N 。Where UP=unit price;DC=direct cost;IC=allocated indirect cost;P=allocated profit;and N=number of units. UP=单价DC=直接成本;IC=分配间接费用; P值分配利润;和N =单位数目。This equation represents the method that is required by many public agency estimating manuals (UDOT 2007);Riverside County 1999;(USACE 1997)and can be taken as the owners perspective on construction cost estimating. 这个方程表示，是由许多公共机构所需的方法估算手册（UDOT 2007年）; 1999年河滨县（美国陆军工程兵团1997），可作为业主的建筑成本估算的角度考虑。Carr(1989)defines direct and indirect costs as follows: 卡尔（1989）定义的直接和间接费用如下：A direct cost of an activity is physically traceable to the activity in an economic manner. 以某活动的直接成本是可追溯至身体在一个经济的方式活动。A direct cost is one not counted(accrued)if the activity is not performed. 直接成本是不计（应计）如果不进行活动。 Indirect costs are business costs other than direct costs of construction activities;they are not physically traceable and are counted(accrued) even if the activity is not performed . 间接费用是经营成本比其他施工活动的直接费用，他们是可追溯，并没有物理计算（应计），即使不进行活动。 Indirect costs are also known as overhead.间接费用也称为开销。However,Construction contractors tend to use a less theoretical approach, pragmatically separating costs for unit price contracts into fixed and variable costs rather than direct and indirect costs (Carr 1989). 而建筑承包商倾向于使用较少的理论方法，务实分成固定费用和可变费用的单位价格为合同费用比直接和间接成本（卡尔1989年）。 This results in a different way to calculate the same number as 这就导致了以不同的计算方式得出一样的结果。 UP=(FC+VC+P)/N (2)Where FC=allocated fixed cost and VC=variable cost. Once again Carr furnishes a simple set of definitions that are applicable to this approach: FC=固定成本分配和VC =可变成本。再次卡尔furnishes的定义的种方法适用于简单的设置：If a cost changes in proportion to a change in volume or quantity, it is variable. 如果在数量比例或数量变更费用的变动，它是可变的。If a cost remains unchanged in total, despite wide fluctuations in volume or quantity, it is fixed(Carr 1989). 如果成本维持不变，尽管在总数量上还是在数量大幅度波动，它是固定的（卡尔1989年）。The reason for the changed perspective has to do with the dynamics of the unit price contract itself. 为改变观点的原因，是因为有单位价格合同本身的动态。 As the total variable cost changes proportional to the number of units installed, the contractor will always recover its variable costs and therefore it is not at risk for the variable costs. 由于总可变成本变化成比例的单位数目，安装承包商将永远收回其可变成本，因此，它不是在为可变成本的风险。 However, the contractor is at risk of not recovering the amount of fixed cost and target profit that it has allocated for a given work item if it does not install the engineers estimated quantity of units upon which it was required to bid.然而，承办商在未收回固定成本和目标利润，它已经为给定的工作项目，如果它不安装工程师的后，它被要求投标单位的估计数量分配数额的风险。 Conversely, if the contractor installs more than the bid quantity for this item, it will recover the complete fixed cost for that item once it has installed the bid quantity and the allocated fixed cost will become a windfall profit for the number units installed above the bid quantity. 相反，如果承包商安装比此项目投标的数量更多，这将恢复该项目的完整的固定成本，一旦安装了投标数量和分配的固定成本将成为暴利的数量单位安装了上述出价数量。 Therefore, it can be seen that it is logical to account for costs in a manner that reflects the risk inherent to contracts payment mechanism. 因此，可以看出，这是合乎逻辑的方式，在一个固有的风险反映到合同的费用帐户支付机制。 It also allows for a more precise accounting for costs by directly associating different types of fixed costs with specific work items rather than accumulating all indirect costs and then arbitrarily allocating them to work items on a percentage basis.它还允许一个由直接关联，而不是所有间接成本，积累与特定工作项目的不同类型的固定费用，然后分配给任意一个百分点的基础工作，更精确的核算项目成本。Many public owners recognize the contractors risk of quantity underrun as well as their own risk of quantity overrun and provide for renegotiation of unit price for work items whose actual quantities vary more than a given percentage of the bid quantity (Schexnayder and Mayo 2004). 许多公共业主认识到承包者的风险溢数量以及他们对自己的风险溢出数量，并提供工作项目的单位，其变化比投标数量（施克斯纳德和Mayo 2004）更实际数量一定比例的价格重新谈判。Below is a list of typical quantity variation ranges above and below which the agency will allow the bid unit price to be renegotiated下面是一个典型的数量上面和下面该机构将允许投标单位的价格变化范围进行重新谈判的清单:New Mexico DOT:20%(NMDOT 2000) 新墨西哥点：。 20（NMDOT 2000）;Oklahoma DOT: 25%（ODOT 1999）俄克拉荷马点：。 25（ODOT 1999）；Texas DOT: 25%(TxDOT 2004) 德州点：。 25（TxDOT 2004）;Utah DOT:25%(UDOT 2007) 犹他州点：。 25（UDOT 2007）;West Viurginia DOT: 25%(WVDOT 2000) 西Viurginia点：。 25（WVDOT 2000）;and和USACE: 15%(USACE 1997). 美国陆军工程兵团： 15（美国陆军工程兵团1997年）. Table 1. Balanced Bid Example Hot-mix asphaltic concrete (HMAC) pay item Unit price element Description Total cost Bid quantity Unit costVariable cost Materials,labor,and equipment $3.85M 50Kt $77/tFixed costs Mobilize/demobilize plant and equipment $250K 50Kt $5/t Allocated overhead,financing,etc. $300K 50Kt $6/tTarget profit $100K 50Kt $2/t Final bid totals $4.5M 50Kt $90/tOther agencies,such as the Alaska DOT,(ADOT&PF 2004),do not contain such clauses in their unit price contracts. 其他机构，例如阿拉斯加的DOT（ADOT及公积金2004年），不包含在他们的单位价格合同等条款。This creates a situation where the risk of underrun quantities is unbounded and therefore increased. 这将创建一个凡欠载量的风险是无限的，因此增加的情况。By including a unit price adjustment clause,the owner is limiting both its own and the contractors quantity variation risk. 通过包括单位价格调整条款，业主是其本身的限制和承包商的数量变化的风险。 This issue is best illustrated by example.Table 1 shows the contractors estimate for a pavement work item on a state project where the unit price adjustment clause allows a variation 20% before the unit price can be renegotiated. 这个问题是最好的说明例子。表1显示了承包商对项目上的路面状态估计那里的工作项目单价调整条款允许变化 20的单位之前的价格可以重新谈判One can see that the contractor chose to associate the cost of mobilizing and demobilizing the asphalt batch plant and associated equipment with this particular work item. 人们可以看到，选择承包商联营调动和遣散的沥青搅拌站的费用以及与此特定的工作项目相关的设备。Additionally,a proportional amount of the overhead and other general fixed costs and target profit was also allocated to this item. 此外，间接费用和其他一般固定费用和目标利润总额的比例也分配给这个项目。Thus,the unit price of $90.00 per ton is a balanced unit price. 因此，每吨90.00美元的单价是一个平衡的单位价格。From Table 1,one can develop an algebraic formula to calculate the contractors cost for the actual number of units installed从表1，可以建立一个代数公式来计算的单位实际安装的数量承包商的成本。Actual cost = Total FC + VC(N) . 实际成本=总界别+创投（N）的。The Ohio DOT (2005) takes this a step farther by quantifying a mathematically unbalanced bid by requiring:“Bidders must bid at least the cost of the materials for every item bid.”The Texas DOT regulations (TxDOT 2004) agree with both Oklahonma and Nhios interpretations. TxDOTs specifications in concert with federal regulation 23CFR 635.114 (CFR 2008) go on to state that a contract may be awarded to a mathematically unbalanced bid but must reject a materially unbalanced bid. TxDOT points out two situations in which material unbalancing are found: “There is an error in the engineers estimated bid quantities (too low) and the contractor bids a high price on these items. In this case, the apparent low bidder might not be the actual low bidder once the quantity error is corrected.” The contractors bid prices are high on items of work occurring early in the project. In this case, the apparent low bidder might not be the actual low bidder when the States financial loss of potential interest income is calculated (TxDOT 2004).The second TxDOT definition refers to a situation that is commonly called “front-loading” (Schexnayder and Mayo 2004). Front-loading can become a form of mathematical or material unbalancing. Front-loading is done to generate additional cash flow in the early phases of the project (Mayer and Deikmann 1982). As this issue is not created by the engineer who develops the bid quantities on a unit price contract, it is beyond the scope of this study. Therefore, the paper will restrict itself to evaluating unbalancing only and make no effort to identify potential front-loading in the sample population.All three state DOTs cited above are allowed to award contracts to mathematically unbalanced bids and must reject materially unbalanced bids. Thus, it can be concluded that mathematical unbalancing is an expected practice due to the possibilities of errors in the engineers estimated bid quantities, and that at least these three agencies see mathematical unbalancing as a necessary part of unit price contracting. However, materially unbalancing a bid is deemed detrimental when it appears that it will ultimately result in final cost that causes the agency to pay more that it would have paid if the bid had been balanced. The above discussion leads to the inference that the ethical line has been crossed when a unit price is materially unbalanced, i.e, bid at a price that is lower than its variable cost. Therefore, it is important that engineers and construction contractors both understand and differentiate between mathematical and material unbalancing.To s