County-owned bridges should be capitalized at historical or estimated historical cost  and depreciated as infrastructure. The Tennessee Department of Transportation  bridge inspection reports are an excellent source of information for determining the  construction date and dimensions of most, if not all, county-owned bridges. If the  actual historical cost of the bridge cannot be located, a county can use an estimated  historical cost by using a deflation calculator to index current bridge construction  cost back to the year of construction. All bridges acquired on or after July 1, 1980,  and above the county’s capitalization threshold should be capitalized. Major  renovations and repairs, that are not considered routine maintenance and upgrades  (wood to concrete, etc.) to bridges, that exceed the capitalization threshold also  should be capitalized and depreciated. 

Example 1:  
Blue County has a bridge that was originally built with a wooden floor in 1945. The  bridge was upgraded to a concrete span in 1985. The county implemented GASB 34  in 2006 and retroactively reported the bridge as a concrete span with an acquisition  date of 1985 (when the upgrade took place).

Example 2:  
Blue County has a concrete box-type bridge that originally was constructed in 1983;  however, the bridge had extensive damage in a storm and had major repairs (that  extended the bridge’s original useful life) in 1993. The bridge would be capitalized  with an initial acquisition date as of 1993 (the date of the major renovation).