Cover Image

Not for Sale



View/Hide Left Panel
Click for next page ( 122


The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement



Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.

OCR for page 121
86 Estimating Soft Costs for Major Public Transportation Fixed Guideway Projects LIGHT RAIL HEAVY RAIL LIGHT + HEAVY RAIL 60% 60% 60% PE + FD (% of Construction) PE + FD (% of Construction) PE + FD (% of Construction) 2 2 2 R = 0.01 R = 0.12 R = 0.16 50% 50% 50% 40% 40% 40% 30% 30% 30% 20% 20% 20% 10% 10% 10% 0% 0% 0% 0% 50% 100% 0% 50% 100% 0% 50% 100% % of Guideway Not At-Grade % of Guideway Not At-Grade % of Guideway Not At-Grade 2 2 2 R = 0.01 t-Stat = -0.35 R = 0.12 t-Stat = -1.74 R = 0.16 t-Stat: = -2.96 Figure 56. Engineering soft costs as a percentage of construction versus percentage of guideway not at grade (retained cut and built-up fill designated as "at grade"). rail shows a slight downward trend and heavy rail shows a slight upward trend, but the combined project database is flat and all relationships are not statistically significant. While the relationships are weak, there may be some decline in engineering soft cost percentage with increasing project complexity. The greater capital costs of these more complex alignments results in higher soft costs, even with a slight decline in the soft cost percentage. Combining the two modes produces a weak negative correlation, surprisingly suggesting that soft costs decline as more aerial and tunnel segments are built. C.10. Soft Costs by Complexity: Percentage of Guideway Below Grade Underground alignment segments introduce several unique costs that other alignment grades do not, particularly excavation and complex structures. This report so far has used per- centage of guideway not at grade as a proxy for complexity; however, the portion of guideway below grade may be a useful indicator of complexity as well. Tunneling and excavating may pro- LIGHT RAIL HEAVY RAIL LIGHT + HEAVY RAIL 60% 60% 60% 2 Admin. (% of Construction) Admin. (% of Construction) R = 0.00 Admin. (% of Construction) 2 2 50% 50% R = 0.03 R = 0.00 50% 40% 40% 40% 30% 30% 30% 20% 20% 20% 10% 10% 10% 0% 0% 0% 0% 50% 100% 0% 50% 100% 0% 50% 100% % of Guideway Not At-Grade % of Guideway Not At-Grade % of Guideway Not At-Grade 2 2 2 R = 0.00 t-Stat = -0.01 R = 0.03 t-Stat = 0.80 R = 0.00 t-Stat: = -0.45 Figure 57. Administration soft costs as a percentage of construction versus percentage of guideway not at grade (retained cut and built-up fill designated as "at grade").

OCR for page 121
Supplementary As-Built Cost Analysis 87 LIGHT RAIL HEAVY RAIL LIGHT + HEAVY RAIL 100% 100% 100% Soft Costs (% of Construction) Soft Costs (% of Construction) Soft Costs (% of Construction) 90% 2 90% 2 90% 2 R = 0.01 R = 0.10 R = 0.07 80% 80% 80% 70% 70% 70% 60% 60% 60% 50% 50% 50% 40% 40% 40% 30% 30% 30% 20% 20% 20% 10% 10% 10% 0% 0% 0% 0% 25% 50% 75% 100% 0% 25% 50% 75% 100% 0% 25% 50% 75% 100% % of Guideway Below Grade % of Guideway Below Grade % of Guideway Below Grade 2 2 2 R = 0.01 t-Stat = 0.39 R = 0.10 t-Stat = -1.62 R = 0.07 t-Stat: -1.98 Figure 58. Soft costs as a percentage of construction versus percentage of guideway below grade. duce a unique set of engineering and management requirements, separate from aerial or built- up fill structures, which might influence project soft costs. Figure 58 shows that the proportion of the alignment in tunnels (cut and cover or deep-bore) has a mixed effect on soft costs as a percentage of construction. Light rail projects showed a slight increase in soft cost percentages as percentage below grade increased, whereas heavy rail projects showed a slight decrease from 30% to 24% with higher proportions of below-grade guideway. The combined project database shows a decreasing trend as well. Figure 59 and Figure 60 present this same analysis, but focus solely on engineering and admin- istration soft costs, respectively. Figure 59 shows that engineering and design soft costs (preliminary engineering and final design) tend to be only slightly negatively correlated to the percentage of guideway below grade, but the pattern is only statistically significant among heavy rail projects. Figure 60 finds a simi- lar general trend for administrative soft costs, but the trend is statistically less significant. Finally, another view into project complexity and soft costs is presented in Figure 61, which examines the effect of guideway grade on soft costs per linear foot and finds a positive correlation that is statistically significant for light rail and both modes combined. This figure is presented on a logarithmic y-axis scale to more clearly illustrate the relationship. Figure 61 shows that more LIGHT RAIL HEAVY RAIL LIGHT + HEAVY RAIL 60% 60% 60% PE + FD (% of Construction) PE + FD (% of Construction) PE + FD (% of Construction) 50% 50% 50% 2 2 2 R = 0.03 R = 0.25 R = 0.10 40% 40% 40% 30% 30% 30% 20% 20% 20% 10% 10% 10% 0% 0% 0% 0% 25% 50% 75% 100% 0% 25% 50% 75% 100% 0% 25% 50% 75% 100% % of Guideway Below Grade % of Guideway Below Grade % of Guideway Not At-Grade 2 2 2 R = 0.03 t-Stat = 0.83 R = 0.25 t-Stat = -2.74 R = 0.10 t-Stat: -2.21 Figure 59. Engineering soft costs as a percentage of construction versus percentage of guideway below grade.