The estimates in Table 5.3 are based on the cost per cubic yard 
of concrete required for construction. Conservative estimates of $150/ 
cubic yard for structural concrete and $75/cubic yard for ballast concrete 
were used in the calculations. In Table 5.4 unit cost figures for 
concrete construction are given for purposes of comparison. The $150 
per cubic yard chosen for MOBS is about 50% greater than the national 
average for buildings and 25% greater than the prevalent estimate of 
$120/cubic yard for floating concrete airports. 
Table 5.4. Comparative Cost of Cast-in-Place Concrete 
Dollars/Cu Yd. 
National average for concrete framed building 
including forms, hoisting equipment, but not 
including finishing.— S$ 92.50 
; 2 b/ 
National average for concrete footings.— 48.00 
FLAIR:£! (a) Reinforced concrete for anchors and 
buoyancy units 120.00 
(b) Prestressed, precast deck panels, 
14" thick (about 16 feet on a side 
(calculated cost)) 105.00 
Bay Area Rapid Transit, tunnel sections 
(estimated cost; also see Part 4) 120.00 
MOBS: (a) Structural concrete (estimated) 150.00 
(b) Ballast concrete (estimated) 75.00 
Sources: 
a/ 
Building Construction Cost Data 1970, Robert Snow Means 
Company, Inc., Doxbury, Mass., p. 36. 
Weidlinger, 1970 
Table 5.5 presents some data on the unit area costs of single level 
floating platforms. The Lake Washington Floating Bridge was completed 
