One in every five bridges in Iowa needs work, according to a report today by The Road Information Program. TRIP’s Frank Moretti says only six states have a higher percentage of bridges that are rated as structurally deficient by the group. A quarter of bridges nationally remain in bad shape and it gets worse as traffic, and the size of trucks, keeps getting heavier. Moretti says the average age on highway bridges in the country has reached forty years.As travel increases, routine maintenance costs go up, and once bridges need big improvements, states find it’s hard to come up with the money. Moretti says it doesn’t mean you’re in danger driving Iowa roads.He says states do a good job of maintaining bridges and if one isn’t safe to carry school buses or fire trucks, authorities will post signs to warn drivers. Moretti says as the bridges continue to age, the need for upkeep will only rise.He points out the bridges are vital to travel and the shipping of goods to towns. The report says one in four of America’s major heavily-traveled bridges is deficient and in need of repair or replacement. Iowa has a low number of bridges rated obsolete in design, but is sixth in the nation for the percentage of bridges ranked by the group as structurally deficient.