178 COLLAPSE OF TEXAS TOWER NO. 4 



collars on A and B caissons were carefully scrutinized and proved to be within 

 niotion. All of the portable connection bolts were in place. The high-tensile 

 connection bolts were secure and appeared to be tight. We did not check these 

 bolts for torque. The collar holding bolts were in place, but several were ob- 

 served to be loosened. The welded diagonal strut attached to the collars was 

 intact and no fractures noted. The sea suctions and discharge connections in 

 the caissons were found to be heavily coated with marine growth. 



HORIZONTAL BRACING OF SPANS, DIAGONAL STRUCTURES 



The horizontal bracing at minus 125 feet was found intact, all pins were in 

 place, and all keepers secured. The clearance around the pins was felt to be 

 within original tolerance of one-eighth inch, plus or minus. No fractures were 

 noted in any of the welded sections. The diagonal struts pinned at each caisson 

 and rising to the center of the horizontal spans at minus 7.5 feet were in place 

 and all caisson pins appeared to have no increase in tolerances. The pins at the 

 upper end at minus-75-foot level had clearance of approximately one-half inch. 

 This play was consistent throughout these particular connections at this level. 



The horizontal spans at minus 75 feet had clearance at the pinned connections 

 at their extremities. The play was found to be greatest in the A and B sections. 

 The span between A and B caisson at the minus-75-foot level at the B caisson 

 connection has approximately 1 inch of clearance. The clearance at the A 

 caisson connection was approximately one-half inch. The diagonal struts ris- 

 ing from this level to the minus-2.5-foot level were in very slight motion at the 

 lower connection but had approximately 1 inch of clearance and in motion at 

 the connection to the minus-25-foot span between A and B caissons. The pins 

 at the extremities of this span have 1-inch clearance at the A and B caissons 

 connection. The triangular bracing between the horizontal spans was found 

 to be in place at all three levels. All welded sections were without noticeable 

 fractures. However, not to be found on the construction drawing were bolts 

 in the connection flanges at each horizontal span. All bolts were in place and 

 appeared to be tight. The welded connections at all three levels on A, B, and C 

 caissons appeared to be in good condition and no fractures were noted in these 

 areas. At the connection of the horizontal span at minus-25-foot level the 4-inch 

 pipe slip joint was found to be fractured. However, there seemed no danger of 

 any part of the section being carried away at this time. 



SUMMARY 



This concern did a similar survey on tower No. 4 last October 19.59 [sic 1958] 

 and the results did not show the m.agnitude of clearance to be found in the pins 

 that we have appreciated during this survey. We feel that there is approximately 

 three-quarters inch increase in clearance between the surveys. It should be noted 

 that the above survey was superficial in that we did not remove any of the 

 flanged keepers on the pin extremities, thereby could not determine whether the 

 pins or the flanges were receiving the greatest wear. 



The tower movement is very erratic in an oscillatory direction. The extreme 

 motion seems to predominate in a northerly direction and slightly in a westerly 

 direction. This motion terminates very abruptly in the northerly direction and 

 at times has reverberations at this extremity before recovering to normal. 



The noise factor heard on the tower in the vicinity of a caisson is resulting 

 from the m.otion of the tower taking up total clearance in the pins and flanges 

 on one side or the other to bringing the two metal surfaces together at the ex- 

 tremity of motion causing the metallic bang. 



PLAN BEFERENCE 



Texas TT-4 bracing details, 678262. 

 Texas TT-4 replacement braces, 780310. 



To be found marked in accordance with this survey at base installation office 

 in care of Lt. F. Weaver. 

 Respectfully submitted. 



A. David Crockett. 



