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reinforcing bars begins. Chapter 4 discusses bridge decks which are heavily contaminated with chloride where active corrosion has begun. Chapter 5 discusses the need to provide long-term data feedback to validate the performance of the protective systems.

CHAPTER 2

CURRENT MAGNITUDE OF

BRIDGE CORROSION PROBLEM

To determine the magnitude and extent of the bridge deck corrosion problem, we developed a questionnaire on the subject which was sent to all 50 States and the District of Columbia. The questionnaire requested information in the following areas:

--The extent of the bridge deck deterioration problem.

--The extent to which the States have applied the protective systems to the Federal-aid system bridge decks. --The conditions limiting their application.

--The backlog of bridge decks requiring partial or complete reconstruction.

--The potential effect of the problem if not addressed and corrected.

We received 49 usable responses providing information on the Federal-aid system bridges. This data is summarized below.

RESULTS OF OUR SURVEY

The 49 States 1/ reported having over 235,700 Federalaid system bridges. Seventeen of these States with over 73,000 bridges indicated that the bridge deck situation was only a minor problem. The remaining 32 States, however, categorized their deck problem as moderate to very major. (See app. I.) These 32 States contain over 160,000 Federalaid system bridges. (See table 1.)

1/This includes the District of Columbia, which we refer to as a State in this report for convenience. New Hampshire and Washington did not provide usable responses.

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Little progress has been made by the States in protecting the Federal-aid system bridge decks against premature deterioriation due to corrosion of the reinforcing steel. (See table 2.) For example, 23 of the 32 States with a serious deterioration problem responded that less than 10 percent of their bridge decks have been restored and/or protected against future salt applications. Little improvement can be expected in the future as shown below in table 2.

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Twenty-seven of the 32 States reported that, unless repairs are completed in the next 3 to 5 years, their currently salvageable bridge decks will deteriorate to the point of requiring complete replacement. This results in greatly increased repair costs. For example, a Federal Highway Administration study indicated that, if the 29,000 interstate bridge decks requiring minor repair today were neglected to the extent that they require moderate repair, the current repair cost of about $600 million would increase by an additional $4.4 billion. These estimates are in 1975 dollars.

CHAPTER 3

BRIDGES WITH ONLY SLIGHT CONTAMINATION

NEED TO BE PROTECTED NOW

There are a number of bridges in the Federal-aid system with little or no chloride contamination of the decks. If these bridge decks were protected with one of the systems now used for new bridge construction, significant savings could be realized by avoiding more expensive repairs later.

The potential benefit/cost ratio of repairing and protecting an existing bridge deck requiring only minor repair versus completely replacing the deck at a later date, according to our analysis, is 2.75 to 1. This ratio was computed using present value analysis and assuming a 7-percent discount rate and a 5-percent inflation rate.

States have not had protective systems installed on existing bridge decks, primarily, because of the lack of Federal and State funds. State officials we contacted indicated that funds available for bridge repair are generally budgeted for bridges so deteriorated that replacement of the deck is the only option. As a result, those existing bridges with little or no deterioration will continue to deteriorate, and eventually require repairs that are much more costly than the cost of the protective systems.

LIMITED APPLICATION OF PROTECTIVE SYSTEMS
ON BRIDGES IN GOOD CONDITION

Replies to our questionnaire indicate that lack of Federal and State funds is a major reason why bridge decks still in good condition are not being protected by a majority of the 32 States with a serious bridge deterioration problem. Generally, the States we contacted said that they have a group of bridges so deteriorated that complete replacement of the bridge deck is the only option. Because these bridges have priority for repairs, and all or most of the currently available limited funds are needed to repair them, funds are not generally available for protecting bridges still in good

condition.

Maryland's problem illustrates the predicament facing many States. Premature bridge deck deterioration, according to Maryland Department of Transportation officials, is a major problem in the State. It has 2,057 bridges on the Federal-aid system. As of September 1977, only 70 of these decks had protective systems applied or contracts awarded

to protect them. Moreover, even by 1980, the State estimates that less than 10 percent of its bridge decks will be protected against salt applications. State officials cite insufficient Federal and State funds and a shortage of qualified personnel as the primary reasons limiting application of the protective systems to its existing bridge decks.

Maryland's bridge deck problem will continue to grow because it has more bridge decks needing total replacement than funds available. For example, current inspections have identified 80 bridge decks requiring major repair and a protective system that will cost an estimated $20 million. Of these, 60 decks need complete replacement. When the current inspection program is completed, State officials estimate that the total backlog will be between 200 and 300 bridge decks. If the reconstruction work proceeds at the current rate, it could take 20 years just to complete this work. Meanwhile, other bridge decks will deteriorate, adding to the overall problem.

The Federal Highway Administration has recognized the States' funding problems. In its congressionally mandated report which summarized the overall problem, the Federal Highway Administration noted that, unless States' highway revenues are increased either through increased gas taxes or Federal assistance, the magnitude of the Interstate needs will be beyond the States' highway revenue capabilities.

CONCLUSION

The replies to our questionnaire indicate that the lack of Federal and State funds is hampering the placement of protective systems on bridge decks with little or no deterioration. The potential benefit/cost ratio of repairing and protecting existing bridge decks needing only minor repair versus replacing a completely deteriorated deck at a later date is 2.75 to 1. Without such a protection program, the bridges will begin to deteriorate, and will probably need complete replacement long before originally anticipated and at significantly greater cost.

RECOMMENDATIONS TO THE

SECRETARY OF TRANSPORTATION

We recommend that the Secretary

--identify those bridge decks on the Federal-aid highway system which can be economically restored at the present time,

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