292 



TIMBER BRIDGES AND TRESTLES. 



CHAP. VII. 



"Outer 6 in. X 8 in. Guard Rails are notched for ties, spiked to each tie with one 9 in. X f in. 

 spikes. Each tie to be spiked to stringers with $ in. X 14 in. spikes. Stringers drift-bolted to 

 floorbeams with f in. X 18 in. drift bolts. All f in., in. and I in. bolts to be provided with one 

 O. G. and one slot washer. All contacts of wood and wood to be painted with white lead. Corbels 

 to be creosoted. All holes bored in chord sticks to be creosoted. Inner 4 in. X 8 in. Guard 

 Rails bolted at center and ends of each piece, spiked to each tie not bolted, with one 8 in. X f in. 

 spike and spliced. The 6 in. X 4 in. X 2 in. guard rail is bolted at ends and at intervals of not 

 over 3 ties with f in. special bolts. Leave | in. opening between ends of Guard Rail angles.*' 



The detail plans of a timber Howe truss railway bridge with an 80 ft. span are given in Fig. 8 

 and Fig. 9. This bridge was designed for Cooper's E 55 loading for the allowable stresses given 

 in the specifications of the American Railway Engineering Association. The details and a bill 

 of materials are given on the plans. 



TABLE III. 



BILL OF UPSET VERTICAL RODS FOR ONE 150 FT. 

 HOWE TRUSS SPAN. 



TABLE IV. 



BILL OF LATERAL RODS FOR ONE 150 

 FT. HOWE TRUSS SPAN. 



HIGHWAY TIMBER TRESTLES AND BRIDGES. Details of a highway crossing of 

 the Illinois Central Railroad are given in Fig. 10 and Fig. n. 



A combination timber and iron bridge is shown in Fig. 12; while a short span timber highway 

 bridge is given in Fig. 13. 



For additional details of timber highway bridges, see the author's " The Design of High- 

 way Bridges." 



SPECIFICATIONS FOR WORKMANSHIP FOR PILE AND FRAME TRESTLES TO 

 BE BUILT UNDER CONTRACT.* 



I. Site. The trestle to be built under these specifications is located on the line of 



Railroad at .' County of State of 



2. General Description. The work to be done under these specifications covers the driving, 



framing and erection of a track wooden trestle about ft. long and 



an average of ft. high. 



GENERAL CLAUSES. 



3. The contractor shall furnish all necessary labor, tools, machinery, supplies, temporary 

 staging and outfit required. He shall build the complete trestle ready for the track rails, in a 

 workmanlike manner, in strict accordance with the plans and the true intent of these specifica- 

 tions, to the satisfaction and acceptance of the engineer of the railroad company. 



4. The workmanship shall be of the best quality in each class of work. Details, fastenings 

 and connections shall be of the best method of construction in general use on first class work. 



* Adopted by American Railway Engineering Association. 



