外文翻译Construction projects, private and public alike, have a long history of cost escalation. Transportation projects, which typically have long lead times between planning and construction, are historically underestimated, as shown through a review of the cost growth experienced with the Holland Tunnel. Approximately 50% of the active large transportation projects in the United States have overrun their initial budgets. A large number of studies and research projects have identified individual factors that lead to increased project cost. Although the factors identified can influence privately funded projects the effects are particularly detrimental to publicly funded projects. The public funds available for a pool of projects are limited and there is a backlog of critical infrastructure needs. Therefore, if any project exceeds its budget other projects are dropped from the program or the scope is reduced to provide the funds necessary to cover the cost growth. Such actions exacerbate the deterioration of a state’s transportation infrastructure. This study is an anthology and categorization of individual cost increase factors that were identified through an in-depth literature review. This categorization of 18 primary factors which impact the cost of all types of construction projects was verified by interviews with over 20 state highway agencies. These factors represent documented causes behind cost escalation problems. Engineers who address these escalation factors when assessing future project cost and who seek to mitigate the influence of these factors can improve the accuracy of their cost estimates and program budgetsHistorically large construction projects have been plagued by cost and schedule overruns Flyvbjerg et al. 2002. In too many cases, the final project cost has been higher than the cost estimates prepared and released during initial planning, preliminary engineering, final design, or even at the start of construction “Mega projects need more study up front to avoid cost overruns.” The ramifica tions of differences between early project cost estimates and bid prices or the final cost of a project can be significant. Over the time span between project initiation concept development and the completion of construction many factors may influence the final project costs. This time span is normally several years in duration but for the highlycomplex and technologically challenging projects it can easily exceed 10 years. Organizations face a major challenge in controlling project budgets over the time span between project initiation and the completion of construction. The development of cost estimates that accurately reflect project scope, economic conditions, and are attuned to community interest and the macroeconomic conditions provide a baseline cost that management can use to impart discipline into the design process. Projects can be delivered on budget but that requires a good starting estimate, an awareness of factors that can cause cost escalation, and project management discipline. When discipline is lacking, significant cost growth on one project can raze the larger program of projects because funds will not be available for future projects that are programmed for constructionA history of past project experiences can serve one well in understanding the challenges of delivering a quality project on budget. Repeatedly, the same problems cause project cost escalation and much wisdom can be gained by studying the past. The Holland Tunnel was, when it opened in 1927, the longest underwater tunnel ever constructed and it was also the first mechanically ventilated underwater tunnel. Its initial cost estimate was made by the renowned civil engineer George Washington Goethals. A review of the Holland Tunnel project serves to highlight the critical issues associated with estimating the costs of large complex projects and the fact that even the most distinguished engineers have trouble assessing cost drivers beyond the physical characteristics of a project. Many times there is no recognition of the cost driver s operating outside the project’s physical configuration. A joint New York and New Jersey commission in 1918 recommended a transportation tunnel under the river “Urges new tunnel under the Hudson.” 1918; “Ask nation to share in tunnel to Jersey.” 1918. The automobile was emerging as the predominate means of transportation and it was decided that this tunnel should be for vehicular traffic. As a result the tunnel would employ new ventilation technologies to purge the exhaust gases produced by the internal combustion engine. Eleven designs were considered for the tunnel, most notably, one by the engineer recently responsible for finishing the Panama Canal, George Washington Goethals. He envisioned a single, bileveltunnel with opposing traffic on each level. Goethals made a planning project cost estimate of $12 million and 3 years for construction. World War I had consumed much of the nation’s steel and iron production, so his design made use of cement blocks as the tunnel’s structural shell. His design was the frontrunning plan “Hudson vehicle tube.” but he had responsibilities elsewhere and was not named chief engineer for the project. Clifford M. Holland was named to head the project along with a board of five consulting engineers “Name interstate tunnel engineers.” 1919. Holland came to the project with vast experience in constructing subways and tunnels in New York. The cost of the project was taken to be $12 million, Goethals’ planning estimate. Holland produced a report in February of 1920 based on his a nalysis of the Goethals’ design of the project. His findings were not what had been expected. Holland found • Goethals’ width of 7.47 m would not accommodate the volume of traffic.• Concrete blocks would not withstand the structural loads exerted on the t unnel.• The construction methods required by Goethals’ design were completely untried.• The estimated cost of construction was grossly low.• The work could not be completed in 3 years.The board of consulting engineers gave unanimous support for Holland’s analysis. Holland then presented a design of his own which was supported unanimously by the consulting engineers. Holland’s design, which was a major scope change, called for twin cast-iron tubes. One advantage was that construction would follow established methods of tunnel construction that had been implemented for rail tunnels under the East River and further up the Hudson. Holland estimated the cost at $28,669,000 “Asks $28,669,000 for Jersey tube.” 1920 and construction time at 31/2 years.Debate about the tunnel design continued for more than a year creating disagreements between the New York and New Jersey Commissions and delaying the work—a schedule change. A disagreement about awarding a contract on the New Jersey side further delayed the start of construction and added over half of a million dollars in cost. Construction started on the New York side in October of 1920 and inlate December 1921 the New Jersey portion of the tunnel was bid “Way all cleared for Jersey tunnel.” The mandated completio n date was December 31, 1926. The construction schedule had now grown to 5 years. Estimated project cost increased multiple times throughout the early years of construction as a result of scope creep, schedule delays, and inflation. Increased traffic forecast necessitate larger entrance/exit plazas and acquisition of more right of way “Vehicular tube is growing.” 1923. Then increases in material and labor costs had added another $6 million to the project inflation. By the beginning of 1924, reestimated costs had been increased by $14,000,000 “Vehicular tunnel cost up $14,000,000.” 1924 due to functional and aesthetic factors scope creep. More intricate roadway designs for approaches, widening of the approach roadways, and architectural treatments increased the costs more scope creep. Redesign of the ventilation system added 15.24 cm to the tunnel diameter and $4,422,000. Holland also decided to substitute cast-steel for castiron to increase the strength and safety factors of the tunnel more scope creep. Last, the New Jersey ventilation shafts had to be redesigned along with their corresponding foundations at a cost of $700,000 due to unexpected soil conditions unforeseen conditions. All of these changes increased the estimate to over $42.5 million. New funds were appropriated and it was believed that these were sufficient to complete the project, but by February of 1926, there was another increase of $3,200,000 “$3,200,000 more asked for tunnel.” The commission explained that the new costs were due to increases in labor and material costs challenge in controlling cost. At this time Holland died of heart failure and his assistant, Milton H. Freeman, took over as chief engineer only to die of pneumonia 4 months later. Ole Singstad, the designer of the ventilation system then became chief engineer and brought the project to completion. Having three different chief engineers within 5 months created confusion unforeseen events. In April of 1924 water rushed into one of the tunnels from a leak forcing workers to make a hasty escape more unforeseen conditions. A final appropriation was requested in early 1927 brought the total project cost to $48,400,000. On November 13 of 1927 the tunnel officially opened “Work on tunnel began 7 years ago.” MethodologyThe cost escalation factors that lead to project cost growth have been documented through a large number of studies. Studies have identified factors individually or by groups. Each factor presents a challenge to an agency seeking to produce accurate project cost estimates. As part of a larger study seeking to improve cost estimates and management of costs from project conception to bid day, a thorough literature review was conducted to identify factors that influence cost estimates Anderson et al. 2006. The literature review included exploration of research reports and publications, government reports, news articles, and other published sources. Upon completion of the literature review the factors were analyzed and categorized by the researchers into factors that drive the cost increases experienced by transportation construction projects. This was accomplished by triangulation where multiple investigators or data sources suggested the same factor. This categorization took the individual factors which had been identified in previous research and established a global framework for addressing the issue of project cost escalation. Upon final categorization the cost escalation factor framework was verified through triangulation of data from interviews with more than 20 state highway agencies SHAs around the nation . A previous project that supported identification of the factors had included telephone interviews with all 50 SHAs Schexnayder et al. 2003 . An interview instrument was prepared and tested initially during onsite interview with two SHAs. The revised interview instrument was then sent to the SHAs before the interview so that they could prepare. The interviews were conducted onsite for five SHAs through individual interviews and through a group “peer exchange.” The remaining interviews were conducted by telephone. In all cases, the researchers followed the interview protocol to ensure consistency in data collection. The resulting categorization of cost escalation factors can help project owners and engineering professionals focus their attention on the critical issues that lead to cost estimation inaccuracy.The triangulation analysis considered methodologies from past studies and interviews to create a categorization for the causes of cost escalation. A better understanding of the cost escalation factors is achieved through understanding theforces driving each factor or where the factor originates. With this understanding it is possible to design strategies for dealing with these cost escalation factors. The factors that affect the estimate in each project development phase are by nature internal and external. Factors that contribute to cost escalation and are controllable by the agency/owner are internal, while factors existing outside the direct control of the agency/owner are classified as external. The presentation order of the factors should not be taken as suggesting a level of influence is constructed to provide an over arching summary of the factors. It summarizes the factors into logical divisions and classifications and helps in visualizing how project cost estimates are affected. It is important to note that one of the factors points to problems with estimation of labor and material cost, but most of the factors point to “influences” that impact project scope and timing.中文译文私人和公共的建设项目，一直以来有成本增长的问题。