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• #### Abbreviations used without definitions in TRB publications 135-135

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OCR for page 131
96 Estimating Soft Costs for Major Public Transportation Fixed Guideway Projects LIGHT + HEAVY RAIL: ALL SOFT COSTS LIGHT + HEAVY RAIL: ADMIN COSTS ONLY 60% 35% Management (% of Construction) 50% 30% 25% Soft Costs (% of Construction) 40% 20% 30% 15% 20% 2 10% R = 0.01 2 R = 0.09 10% 5% 0% 0% (2) - 2 4 6 8 (2) - 2 4 6 8 Years of Delay Years of Delay 2 2 Sample Size: 15 R = 0.01 t-Stat = -0.43 Sample Size: 15 R = 0.09 t-Stat = -1.14 Figure 72. Soft costs as a percentage of construction versus years of delay in opening. Figure 73 and Figure 74 examine this potential explanation by comparing the rate of growth of soft and hard costs as the vertical profile becomes more complex. Soft and construction costs are on a per-linear-foot basis, and in every pane construction costs are shown as green diamonds, with a green dashed trend line. Figure 73 shows that for light and heavy rail and both modes combined, as more of the align- ment is in cut and cover and tunnels, construction costs rise faster than soft costs. Figure 74 shows a similar trend when alignment is simply not at grade, although the pattern is less strong. These trends affirm that when the alignment moves from at grade to more complex tunnel, bridge, or aerial structures, construction costs expand rapidly, sometimes faster than soft costs. C.16. Isolating Agency-Specific Effects One potential source of variance within the dataset used here is that financial and construc- tion management practices differ from agency to agency. Where one agency maintains construc- tion inspectors and managers on staff through the operating budget, another agency might LIGHT RAIL HEAVY RAIL LIGHT + HEAVY RAIL \$40 \$60 \$60 Construction Costs Construction \$35 Costs \$50 \$50 Construction Costs per LF (000) Costs per LF (000) 2 Costs per LF (000) \$30 R = 0.38 Costs \$40 \$40 \$25 2 R = 0.19 \$20 2 \$30 \$30 R = 0.18 \$15 \$20 \$20 \$10 2 2 2 R = 0.03 R = 0.27 R = 0.41 \$10 \$10 \$5 Soft Costs Soft Costs Soft Costs \$- \$- \$- 0% 25% 50% 75% 100% 0% 25% 50% 75% 100% 0% 25% 50% 75% 100% % Guideway Below Grade % Guideway Below Grade % Guideway Below Grade 2 2 2 Soft Costs trend: R = 0.41 t-Stat = 3.87 R = 0.03 t-Stat = 0.76 R = 0.27 t-Stat: = 3.94 Figure 73. Soft costs and construction costs per linear foot with percent of guideway below grade.

OCR for page 131

OCR for page 131
98 Estimating Soft Costs for Major Public Transportation Fixed Guideway Projects HEAVY RAIL 60% Soft Costs (% of Construction) 2 R = 0.40 50% 40% 30% 20% 10% 0% 1970 1975 1980 1985 1990 1995 2000 Midyear of Expenditure 2 R = 0.40 t-Stat = 2.69 Figure 75. Soft costs as a percentage of construction versus midyear of expenditure, WMATA only. HEAVY RAIL 60% Soft Costs (% of Construction) 2 R = 0.05 50% 40% 30% 20% 10% 0% 0% 20% 40% 60% 80% 100% Percent of Guideway not At Grade 2 R = 0.05 t-Stat = -0.79 Figure 76. Soft costs as a percentage of construction with percentage of guideway not at grade, WMATA only. HEAVY RAIL 60% Soft Costs (% of Construction) 2 R = 0.08 50% 40% 30% 20% 10% 0% 0% 20% 40% 60% 80% 100% Percent of Guideway Below Grade 2 R = 0.08 t-Stat = -0.98 Figure 77. Soft costs as a percentage of construction with percentage of guideway below grade, WMATA only.

OCR for page 131
Supplementary As-Built Cost Analysis 99 from the full database of heavy rail projects. The trend line shows a declining trend from a high of 30% to a low of about 22%, but the relationship is not statistically significant. Note that some WMATA projects are 100% below grade. These results suggest that below-grade alignment has no effect on soft costs as a percentage of construction costs. These WMATA Metrorail results do not support the full heavy rail database, nor do they demonstrate consistent relationships that may be expected for projects from the same agency. The results from the preceding WMATA-only data demonstrate the difficulty in identifying project characteristics that can be used to help estimate construction soft costs of major public transportation capital projects.