11. Data Processing and Analysis. Conversion of the collected data to significant units and the maintenance of tabular records or graphical plots thereof will be accomplished to the maximum feasible extent within the project office. At this echelon graphical time plots will be maintained for the hydrostatic uplift pressure data, interior drainage inflow rates, direct-reading gages at joints and cracks, and other collected instrumentation results not requiring complex mathematical or arithmetical reduction processes. Tabular records or graphical plots will be continuously maintained for examination upon short notice, and such data made available to the inspection party at the time of each periodic inspection. Division Engineers will provide permanent written instructions to project engineers regarding reporting of instrumentation results, including emergency reports on unusual developments.

12. Evaluation of Results.-Evaluation of the instrumentation data, as related to the behavior and safety of the structure, will be a continuous operation, carried out as each new set of observations is obtained, processed, and tabulated and plotted. Where the data indicate abnormal behavior, unsafe movements or deflections, or loading which adversely affect the stability or functioning of the structure, prompt notification of such circumstances will be transmitted to the next higher echelon.

13. Summary of Results.-Condensed tabulations or graphical plots will be prepared as required for inclusion in each general inspection report. Format and scope of the report exhibits will be determined by those responsible for preparation of the inspection report.

The CHAIRMAN. Senator Cooper.

Senator COOPER. I have read your statement, Colonel Anderson. I think it is very helpful.

I was interested in your statement about bridge loading. As I understand, one of the recommendations you make is that the load limit for a bridge be marked very plainly, so that travelers will at least be notified of the danger of overloading the bridges; is that correct?

Colonel ANDERSON. Yes, sir.

Senator COOPER. When you speak of one load limit, are you talking about the total load which should not be exceeded on the bridge at one time, or are you speaking of the maximum weight of a vehicle permitted on the bridge, or both?

Colonel ANDERSON. Generally speaking, we would recommend that the bridge be posted for the load limit of the largest vehicle that should pass over the bridge.

Senator COOPER. What significance do you give to the number of vehicles permitted on the bridge at the same time? You spend a good deal of time in your statement talking about the number of vehicles that should be on the bridge.

Colonel ANDERSON. Yes, sir. It may be a problem of spacing, too, of the vehicles and bumper-to-bumper tractor trailer trucks may overload a bridge whereas one would not, thus some kind of a system of marking the bridge for that purpose, too may be desirable.

Senator COOPER. I think that is correct.

What would you do about bridges on important roads-to give an example, the bridges that enter Washington in rush hours which carry traffic bumper to bumper. How would you deal with the problem of traffic congestion and, most important, safety? Would you still say there should be rules and regulations dealing with the spacing of vehicles?

Colonel ANDERSON. I believe this is where we would feel that point (d) mentioned the statement, the review of design standards, would be desirable. Generally speaking, modern standards in the design of bridges is such that it takes into account the high present

modern loads that these bridges are subjected to, and proper safety are also taken into account.

Senator COOPER. I think your statement emphasizes that even with all the improvements that can be made and the precautions that can be taken, it would take a long time to bring the majority of the bridges in this country up to better standards.

Colonel ANDERSON. That is right, sir.

Senator COOPER. I don't know whether this is your field or not, but you may know about it. We have a related bill before this committee, S. 2658, which would permit to States to increase the load limits of vehicles from 18,000 to 20,000 pounds in the case of single axle, and for tandem axles from 32.000 to 36,000 pounds.

Considering the condition of the majority of bridges in this country, the standards to which they were built years ago for different kinds of traffic, would you say that such an extensive step should be taken with respect to bridge loadings?

Colonel ANDERSON. Sir, I have not studied the particular bill you mentioned and I don't believe that I could comment on it at this time. If you increase the vehicle sizes, it would seem to me that it follows that some of the weaker bridges in the country then become more hazardous.

The CHAIRMAN. Thank you, Senator Cooper.

Senator Spong.

Senator SPONG. Mr. Chairman.

I am not sure that I understood your answer to one of Senator Cooper's questions.

Would these load limit markings contemplate the limit for one vehicle or the total limit on the bridge at any one time, or both?

Colonel ANDERSON. We have to take into account both the spacing of the vehicles and the load of an individual vehicle. It, of course, changes, depending on the length of the span. In sone cases, you can only get one vehicle on the span anyhow so it is no different. In other cases where you have long spans and many vehicles are involved in loading the span at any one time, then you would have to have a spacing requirement, if it were determined that the bridge is hazardous to modern traffic.

Senator SPONG. That brings me to my next question.

Later in your statement-whereas I would quite agree with you that periodic supervision of traffic would be desirable-from a practical standpoint what do you contemplate could be done?

Colonel ANDERSON. I recognize it is a very difficult problem, sir, to constantly police every vehicle going across many of the bridges in the country.

Senator SPONG. Do you contemplate the use of more weighing stations?

Colonel ANDERSON. The intention of the recommendation here is primarily to provide surveillance to assure the agency in charge of operating and maintaining the bridge that the load limits are not being exceeded; and if their surveillance determines that they are frequently being exceeded, then more restrictive measures would have to be adopted.

Senator SPONG. Well, I am in sympathy with the suggestions, but I have some serious doubts as to its application.

Colonel ANDERSON. Yes, sir.

Senator JORDAN of Idaho. Thank you, Mr. Chairman.

I am sorry I was detained and I didn't get in here to hear your statement when you presented it. I am reading it hurriedly and I am impressed where you say:

It appears that in most areas of the country there is no fully effective control of the weight of vehicles that can be placed on a highway bridge at one time. I believe all states have limits on the weight of single vehicles that may use their highways. But it is possible to overload a bridge with vehicles, all meeting state standards for gross weight.

I think that is the key to the problem. I don't know how we are going to control the bridge traffic to prevent coincidence of having the heaviest of combination of vehicles concentrated at one time in the longest and weakest span of our bridges.

Do you have any ideas about how we might regulate that?

Colonel ANDERSON. Where the bridges will not take the traffic or at least where the bridges would not take the projected traffic, then traffic control seems to be the solution until the bridges are strengthened or replaced.

Recognizing the problem, we cannot just say that no problem exists and do nothing about it.

Senator JORDAN of Idaho. And that would involve posting bridges to certain load limits.

Colonel ANDERSON. Yes.

Senator JORDAN of Idaho. It is very difficult to control the traffic going two ways on a bridge. The coincidence of your heaviest combination of vehicles meeting at that moment in the center of your longest and weakest span, how would one regulate that by regulation?

Mr. WENDELL JOHNSON. I might say, Senator Jordan, that we recognize, of course, that none of these measures alone will solve the problem and it is only by application of every possible measure that we feel that we can do some good here.

We feel that in order to let the people know what kind of traffic the bridge can take that there must be some form of marking and there must be a program of education along with this to let the driving public and particularly the truckers know what the system is.

Then this, coupled with some surveillance from time to time to let us know how it is working out, we think will make an improvement. We recognize, however, that even this would not assure in every case that an accident would be prevented.

Senator JORDAN of Idaho. You recognize there are limitations as I do. In other words, with the railroad business, we will say, with the traffic all one way it is quite possible to anticipate what that loading is going to be, but when you have traffic going both ways I think it is almost an impossibility to project the stresses to which that bridge is likely to be put at any time.

Colonel ANDERSON. In designing a new bridge, sir, you can take that into account.

Senator JORDAN of Idaho. Yes; I can appreciate that, but 100,000 bridges were designed prior to the present concept of load weights and load limits and are entirely inadequate to meet that emergency.

Colonel ANDERSON. For this reason we have a real problem, sir.

Senator JORDAN of Idaho. That is all, Mr. Chairman.
The CHAIRMAN. Thank you, Senator Jordan.

Thank you, Colonel Anderson.

Thank you, Mr. Johnson.

Colonel ANDERSON. It has been our pleasure, sir.

The CHAIRMAN. Senator Cooper must leave to keep an engagement. We appreciate your having come for this length of time this morning. Senator COOPER. I would just like to say that I attended all of hearing yesterday, and I want to be here as much I can. I think this is a tremendously important subject. I am very sorry I cannot hear the next witness but I have looked over Mr. Morton's testimony and it seems a very fine statement.

The CHAIRMAN. Mr. Morton.

Mr. Goodman.

Thank you, Mr. Morton.

Thank you, Mr. Goodman.

If you, President Morton, will proceed in introducing, if you will, your associates.

STATEMENT OF JOHN O. MORTON, PRESIDENT, AMERICAN ASSOCIATION OF STATE HIGHWAY OFFICIALS, AND COMMISSIONER, NEW HAMPSHIRE STATE HIGHWAY DEPARTMENT; ACCOMPANIED BY WARD GOODMAN, COMMITTEE ON BRIDGES AND STRUCTURES, AND DIRECTOR OF HIGHWAYS, STATE OF ARKANSAS; AND ALFRED E. JOHNSON, EXECUTIVE DIRECTOR, AMERICAN ASSOCIATION OF STATE HIGHWAY OFFICIALS

Mr. MORTON. Thank you, Mr. Chairman.

The statement that I do have is rather a lengthy statement. Would you prefer to have me condense it? Part of it goes into the history of our bridges, going back some time.

The CHAIRMAN. Off the record.

(Discussion off the record.)

The CHAIRMAN. Let us begin the statement. We will see how we progress.

Mr. MORTON. Fine.

Mr. Chairman and distinguished members of the Senate Subcommittee on Roads, we appreciate this opportunity to discuss with you the current procedures in use in the State highway departments for bridge inspection and maintenance.

I am John O. Morton, commissioner of highways for the State of New Hampshire, and am appearing here as the president of the American Association of State Highway Officials.

Our association includes all of the State highway departments, plus the departments for the District of Columbia and Puerto Rico.

Our membership is by department, and the top two administrative officers of each department are eligible for election to our executive committee.

We usually draw chairmen for our various committees from the chief administrative roster and select individuals who have extensive experience and background in the particular subject of interest of the respective committee.

I am accompanied here by Mr. Ward Goodman, director of highways for Arkansas, and one of the outstanding authorities on highway bridges, and also by our executive director of the association, Mr. A. E. Johnson.

Mr. Goodman serves as chairman of our committee on bridges and structures, which is made up of the chief bridge engineer of each of our member departments.

Mr. Goodman is not going to present a prepared statement, but he is available to the committee for answering any questions that you may wish to direct to him.

It is our intention to first give you some background in the development of highway bridge technology, for we believe that a hearing such as this would be incomplete without this information in the record.

In the early dawn of building public works and important temples, arches and beams were utilized. Stone arches were used to support the viaducts that carried spring water from the mountains to the Roman cities and to span ravines and rivers for the early Roman road network that was started about 300 B.C.

During the 16th century, such minds as Galileo and Michelangelo understood the scientific theories of columns and beam action, as well as the resolution of forces by completing a parallelogram force diagram, drawn to scale.

However, in that age, there were limitations on suitable materials. for structures, so the stone arch was generally used, as mentioned above, and many of these structures are in existence today, at least in part. Wood was generally limited to relatively short span structures.

Scientific bridge design, particularly the more economical and complicated truss type, evolved from an art directed by guess and judgment over the years to the precise analytical computations of today.

Prior to 100 years ago, truss bridge design was generally done by drawing out what seemed necessary to do the job, based on professional experience, then constructing scale models and loading them to destruction.

If weaknesses developed during the construction of the bridge, additional members, guys or supports were added at that time.

There still are some very old bridges of this type in service and many of them contain redundant and unneeded members in truss assemblies. I refer particularly to the early wrought iron lattice

trusses.

In the United States, where areas are large, distances great, and many rivers and streams encountered, bridge building had to be developed in order to accommodate necessary transportation and commerce. Bridges were essential for the needs of a growing and complex society and for expanding westwardly.

In the early days, ferries were used to a great extent in place of bridges, and some few of the primitive current-operated ferries can still be found in the United States in the low traffic areas.

Early highway bridges were of wood or of stone arch construction. Piers and abutments were generally of stone.

When the bridge was of wooden truss configuration, the bridges were covered, inasmuch as wood preservatives were not in use at that time and the bridge timbers had to be sheltered to prevent decay.