【正文】 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 cm to the tunnel 浙江工業(yè)大學(xué)之江學(xué)院畢業(yè)設(shè)計(jì)（論文） 外文翻譯 8 diameter and $4,422,000. Holland also decided to substitute caststeel 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 $ million. New funds were appropriated and it was believed that these were sufficient to plete the project, but by February of 1926, there was another increase of $3,200,000 “$3,200,000 more asked for tunnel.” The mission 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 pletion. 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.” Methodology The 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. 2020. The literature review included exploration of research reports and publications, government reports, news articles, and other published sources. Upon pletion 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 acplished 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. 2020 . An interview 浙江工業(yè)大學(xué)之江學(xué)院畢業(yè)設(shè)計(jì)（論文） 外文翻譯 9 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. Cost Escalation Factor Classification 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 underst