Office of the General Manager
100 Railroad Avenue
Monetesano, Washington
CIRCULAR NUMBER: 8.15 DATE: January 1, 1955
S.B.Clinard
President and General Manager ___________________________________________________________________________________
Inspection of Bridges
Every bridge should be inspected thoroughly at least twice a year, once in the spring and once in the fall. A few light-traffic roads omit the spring inspection and many heavytraffic roads require additional inspections. Bridges are inspected once a month on the New York Central Lines.
When less frequent inspections are required, all structures should be inspected in a general way each month by section- and bridge-foremen. If frequent inspections are required, they are made by special bridge-inspectors. Otherwise the fall inspection is made by an engineer of the bridge department in company with the supervisor of bridges and buildings or the master carpenter, and the spring inspection is made by the supervisor alone. The notes as to condition of the structure should be recorded at the structure during the progress of the inspection. The inspector should have with him the notes of the previous inpection and ordinarily it is necessary to take notes only to show any change in the condition of the structure since the last inspection, and whether the repairs recommended at the last inspection have been carried out properly. If the inspector considers immediate attention necessary he should at once call in the services of the nearest section-gang.
The spans, bents, or piers of a bridge or trestle should be designated by numbering them in the direction of the bridge-numbers, commencing with No. 1 at the abutment, back bent, or sill. The panels of a truss bridge should be numbered in the same way. Trusses should be designated as right or left according to the direction of the bridge-numbers.
The most important points to be inspected in a steel bridge are the following:
1) The rollers must move freely, be at right angles to the line of the bridge, and be free of cinders or rubbish.
2) Posts and compression members must be free from bends or bulges, and all joints must have a firm and even bearing against each other.
3) Tension members must 'show no slackness and should be adjusted so that they will be equally stressed in any panel. Rods must be adjusted when there is no live load on the bridge.
4) Floor beams and stringers require careful examination for flaws in connecting angles, for defective, loose, or missing rivets, and for shearing and crushing of webs and flanges at connections.
5) All riveted members should be tested with a hammer to detect loose rivets, and if any are discovered they should be marked plainly and replaced as soon as possible.
6) Bridge seats must be examined for cracks or evidence of crushing, and to see that they are level.
7) The structure should be carefully watched under the passage of trains. Swaying, excessive deflection, twisting, and rattling of members is evidence that attention is necessary.
Retaining walls, culverts, piers, abutments, and other masonry structures must be examined for undermining, scouring, bulging, settling, or other movement, cracking, or other defect or dangerous indication.
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