| Show modern trains travel on wood from the time of wood burning steam engines wood has been acen cs essential in the construction opera tion and maintenance 0 of I 1 sl ji roads with the 0 7 stokers smokers and oil burning diesem locomotive co engines the use of wool wood as fuel ceased to be important however these diesel or other pow red engines pulling streamlined coaches or freight cars must I 1 depend upon wood to function points out the U sa S forest products labe laboratory Mi madison dison Ws today more than a billion wooden ies acs are in use in the anted un ted states enough if placed end to end to encircle the earth 70 times in recent years abbit 50 10 million wooden railroad ties have been purchased annually of wh ch more than have hava been t dively iv ely treated ties are cut from a n umber number of kinds of wood many are hewn by hand the preference however is for eabe because of their greater ity lower cost of treatment and better handling qualities some 30 years ago the railroads in germany turned from wooden cross ties to iron and steel ties in recent years they have bave been going back to the wooden tie because experience has shown that when properly creosoted it is less expensive and more satisfactory than the metal tie the reason why wood cross ties tie s have held their position in competition with other materials and a flood of inventions vent ions is quite definite the american railway track is a flexible yielding mechanism constructed ted so as to yield to the terrific impacts of rushing masses of iron yet elastic enough to retain its form and strong enough to bear the great loads placed upon it it is built of ballast ties tie plates spikes and rails in this complex assembly the wooden tie plays a leading role because of its cheapness strength elasticity resistance to shock and relative ease of replacement not to speak of its electrical insulating properties which are necessary to the operation of an increasing mileage of automatic signal systems ties sometimes last 30 or 40 years and their average life is increased as a result of both preservative treatment and better service conditions whatever the improvement in building railroad tracks it is all in favor of the wooden tie which has weathered hard s service er ice and now seems established long time to come |
