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OCR for page 74
74 Table 61. Condition report for reinforced Table 63. Condition differences for reinforced concrete abutment. concrete abutment. Condition State q 1 2 3 4 1 2 3 4 Reinforced Concrete Abutment 40% 20% 40% 0% Reinforced Concrete Abutment +40% 0% -40% 0% Element Improvement total cost of the maintenance event is allocated equally to all elements. The quantity of element that is improved is computed as the sum of gains in element quantities in better condition Event TotalCost AllocatedCostelement = (Eq. 4) states. The improved quantity is computed as Element Count j ImprovedQuantityelement = qi while qi 0 (Eq. 3) Where i =1 ElementCount is the number of elements in the short list Equation 3 computes improvement quantity as the sum of Now the unit costs for actions and elements are computed non-negative quantity changes in better condition states. The using Equation 1. sum terminates before the first negative quantity changes. The transition in conditions is obtained as well. The best con- dition state with a negative quantity change is the prior condi- Element_Unit_Cost_Table tion for the element, the worst condition state with a positive quantity change is the post condition of the element. Element unit costs are reported in a table that is generated An example for operation of Equation 3 is provided. Con- by the NBMD viewer application. The element unit cost table sider that a reinforced concrete abutment that has minor dete- is a derived table. Its entries are collected or computed from rioration for 20% of its width and defects for 40% of its width. other NBMD tables. Data fields in the unit costs table are The condition report for this element is shown in Table 61. listed in Chapter 2. A repair action is performed on the worst defects at the The element unit cost table contains a record for each ele- abutment. The result is that sections that had been in condi- ment in each maintenance event. Records list maintenance tion state 3 are improved to condition state 1. The condition events, components and operations for maintenance actions, report, after repair, is shown in Table 62. inspections before and after maintenance, element identifica- Differences in element quantities are computed using tions and units, allocated costs, inventory changes, improved Equation 2. Results are shown in Table 63. quantities, and unit costs. Operation of Equation 3 yields an element improvement quantity equal to 40% of the element quantity. The summa- tion includes condition states 1 and 2, but not state 3 since its List of Element Unit Costs change is a loss (removal, actually) of element quantity due to Element-level costs are computed from data collected from the effects of repair action. the California DOT, Michigan DOT, Oregon DOT, and Ten- Elements that show positive values of improved quantity nessee DOT. Data from the Pennsylvania DOT do not have are kept in the cost computation. Elements that do not show sufficient number of element-level inspections to evaluate improvement are eliminated. improvement quantities for elements. The complete list of element-level unit costs of actions is presented in Appendix C. Cost Allocation The list presents median unit costs by DOT in the order of element numbers. For each element, a matrix of costs is pre- After obtaining the short list of elements that are the sented that indicates the condition state before maintenance, right bridge component and that show improvement, the the condition state after maintenance, the unit cost, and the maintenance operation. Table 62. Condition report for reinforced concrete abutment, after repair. Comparison Condition State 1 2 3 4 Element-level maintenance costs are compared for bare Reinforced Concrete Abutment 80% 20% 0% 0% concrete deck in Figure 41. The operations include Main-

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75 California Condition After 12 Concrete Deck - Bare 1 2 3 / square meter 1 $ 0.30 Maint 2 $ 106 Coat Condition Before $ 1.70 Repair 3 $ 1.20 Repair 4 $ 0.82 Repair 5 Michigan Condition After 12 Concrete Deck- Black Bars 1 2 3 /square meter 1 $ 11.41 Coat 2 $ 12.81 Repair Condition Before $ 8.51 Coat 3 $ 6.94 Repair $ 19.15 Repair 4 $ 18.85 Repair $ 52.15 Repair 5 $ 67.08 Repair Oregon Condition After 12 Concrete Deck - Bare 1 2 3 / square meter 1 2 $ 0.07 Maint Condition Before 3 $ 0.14 Repair 4 $ 0.02 Maint 5 Tennessee Condition After 12 Concrete Deck - Bare 1 2 3 / square meter 1 2 Condition Before 3 $ 0.32 Repair 4 5 Figure 41. Element-level costs for concrete deck. tenance (unspecified action), Coating, and Repair. All Other comparisons may be made among DOTs for unit costs are per square meter of deck. Costs are similar for costs for maintenance of similar bridge elements. Some gen- California, Oregon and Tennessee, but differ strongly for eral trends are apparent. Costs for replacement are often Michigan. Michigan costs are taken from maintenance higher than costs of repairs. Costs for repairs increase for ele- contract data. Costs from the other three DOTs are crew ments in poorer condition states. However, unit costs vary costs. considerably among DOTs and among condition states. Estimates of Pontis costs for deck repairs are collected from Delaware and Louisiana and shown in Figure 42. Cost Condition % of Delaware Cost Louisiana Cost estimates from Delaware and Louisiana were collected in State Deck / square meter / square meter 2 1 $ 2.01 $ 0.90 the 2009 domestic scan on bridge management decision- 3 6 $12.08 $ 5.40 making (NCHRP Project 20-68A, Scan 07-05). The com- 4 17 $ 34.23 $ 15.31 puted costs for California, Oregon, and Tennessee are in 5 25 $ 50.34 - the same range of values as the estimated costs for Delaware and Louisiana. Figure 42. Estimated costs of Pontis actions.