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OCR for page 123
88 Estimating Soft Costs for Major Public Transportation Fixed Guideway Projects LIGHT RAIL HEAVY RAIL LIGHT + HEAVY RAIL Admin. Costs (% of Construction) Admin. Costs (% of Construction) Admin. Costs (% of Construction) 60% 60% 60% 2 2 2 R = 0.06 R = 0.07 R = 0.02 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 Not At-Grade 2 2 2 R = 0.02 t-Stat = -0.72 R = 0.06 t-Stat = -1.23 R = 0.07 t-Stat: -1.87 Figure 60. Administration soft costs as a percentage of construction versus percentage of guideway below grade. complex alignment profiles are consistently tied to higher soft costs per linear foot and that the relationship is statistically significant for light rail and the combined project database. The percentage of guideway not at grade or below grade therefore appears weakly related to soft costs when measured as a percentage of construction costs. When soft costs are measured in dollar terms per linear foot of guideway, however, a stronger relationship appears: more com- plex alignment profiles are tied to higher soft costs per linear foot. This finding suggests that more alignment below grade may be driving capital costs in all categories, so that soft costs will rise in dollar value terms but remain unchanged in percentage terms. C.11. Relationships Among Other Category Unit Costs Although it is tempting to measure soft costs in dollar value terms because this measure pro- duces more correlation with expected complexity variables, it is worth exploring the measure further. One benefit of measuring soft costs in percentage terms is that the measure controls for variations in unit costs. Soft cost requirements of more expensive projects can be more consistently compared to inexpensive projects in percentage terms. Measuring soft costs in per-linear-foot LIGHT RAIL HEAVY RAIL LIGHT + HEAVY RAIL $100,000 $100,000 $100,000 Soft Costs per Linear Foot (2008$) Soft Costs per Linear Foot (2008$) Soft Costs per Linear Foot (2008$) $10,000 $10,000 $10,000 $1,000 $1,000 $1,000 R = 0.41 R = 0.03 R = 0.27 $100 $100 $100 0% 25% 50% 75% 100% 0% 25% 50% 75% 100% 0% 25% 50% 75% 100% Percent Below Grade Percent Below Grade Percent Below Grade 2 2 2 R = 0.41 t-Stat = 3.87 R = 0.03 t-Stat = 0.76 R = 0.27 t-Stat: = 3.94 Figure 61. Soft costs per linear foot versus percentage of guideway below grade.

OCR for page 123
Supplementary As-Built Cost Analysis 89 LIGHT RAIL HEAVY RAIL LIGHT + HEAVY RAIL Costs (000) per Linear Foot (2008$) Costs (000) per Linear Foot (2008$) $8 Costs (000) per Linear Foot (2008$) $8 $7 Sitework & Special Conditions Sitework & Special Conditions 2 2 2 Sitework & Special Conditions R = 0.12 R = 0.14 R = 0.16 $7 $6 $7 $6 $6 $5 $5 $5 $4 $4 $4 $3 $3 $3 $2 $2 $2 $1 $1 $1 $- $- $- $- $1 $2 $3 $4 $0 $2 $4 $6 $0 $2 $4 $6 ROW Cost (2008$) (000) per LF ROW Cost (2008$) (000) per LF ROW Cost (2008$) (000) per LF 2 2 2 R = 0.12 t-Stat = 1.75 R = 0.14 t-Stat =1.759 R = 0.16 t-Stat: 2.88 Figure 62. Sitework and special conditions costs per linear foot versus right-of-way costs per linear foot. terms risks autocorrelation between unit costs--high soft costs could be correlated with higher other costs. In general, the analyses below tend to confirm this hypothesis: in dollar terms, soft costs and most cost categories tend to increase proportionately to construction costs. Figure 62 shows that right-of-way costs grow along with sitework and special conditions costs. The relationship is weak, but this finding mildly supports the hypothesis that all categories of capital costs may be growing together, which may help explain the previous results showing that soft costs grow in dollar value, but not percentage terms in relation to complexity (i.e., in terms of percent of alignment not at grade or below grade). Another perspective on the relationships between these soft cost categories is the relationship of guideway costs to right-of-way costs. As shown in Figure 63, these two cost categories appear to be correlated, similar to Figure 30 and Figure 62. The statistical significance is not as pronounced, but the relationship is clear: as right-of-way costs increase, guideway construction costs are also shown to increase. This correlation is best demonstrated for light rail, and the near-zero intercept makes intuitive sense. The heavy rail correlation is statistically insignificant but directionally consistent with light rail. The combined project database also shows a statistical relationship. LIGHT RAIL HEAVY RAIL LIGHT + HEAVY RAIL Guideway Costs (000) (2008$) per LF Guideway Costs (000) (2008$) per LF Guideway Costs (000) (2008$) per LF $30 $30 $30 2 2 R = 0.04 R = 0.14 $25 $25 $25 2 R = 0.33 $20 $20 $20 $15 $15 $15 $10 $10 $10 $5 $5 $5 $- $- $- $- $1 $2 $3 $4 $0 $2 $4 $6 $0 $2 $4 $6 ROW Cost (2008$) (000) per LF ROW Cost (2008$) (000) per LF ROW Cost (2008$) (000) per LF 2 2 2 R = 0.33 t-Stat = 3.27 R = 0.04 t-Stat = 0.90 R = 0.14 t-Stat: 2.66 Figure 63. Guideway construction costs per linear foot versus right of way cost per linear foot.