Show construction OF A CULVERT consideration of economy and safety demands employment of other material than wood by tar far the greater number of cu cul verts and bridges on our public roada road havo have a span omesa than fifty feet in the past these structures have in general been built of wood but lumber so exposed in this dry climate la Is subject to rapid decay writes walter graham in denver deaver field and farm conse these structures require a great deal of repair and frequent renewals the ever increasing price 0 or lum lumber beels ls makhli the further use of 0 wood tor for this class of structures mora inora and more indefensible the loads load which our highway structures are called upon to sustain are also increasing in many of our agricultural localities cali cal ties ittes the tha movement of steam road rollers alers llers and heavy traction engines Is seriously hampered because of weak bridges and cu lverts consideration a ot economy and safety demands inn se of other materials than wood IT iff the construction of culverts cu lverts and bridges durability Is of the greatest economic importance in m ciany any sections a large proportion of tho the annual road levy Is expended in repair and renew renewal a I 1 of wooden culverts cu lverts and minor bridges and it Is not unusual to find this lice defended on the ground that the county or district cannot afford to build the higher priced permanent cul verts this notion la Is simply a false sense of economy true the first cost of the permanent structure Is greater i but there the outlay ends while with wooden culverts cu lverts there Is a large annual outlay for repair as well ss as frequent renewals anyone interested in road improvement will find it most interesting te to secure the following data for his own county or district the number of cu lverts cost of labor and material for repair and renewal each year average life of wooden cu lverts and the ordinary ufa life of wooden bridge floors then he could compute how long it would ie be before the actual present cresent would pay tor for pen manent cu lverts later late improvements in the ture oi 01 iron have made this material more generally available for use in cum vert construction A special quality of 0 iron very low in carbon resists cori cor roslon so BO well as to make its use advisable in many cases and this la Is ari an important point for the irrigated districts the cutting away of the soil by he be wat waier er at the inlet or outlet of 0 a chhy pipe Is often cespon i sible elble tor for iab Us progressive breakdown break down and j partial brifil ex exposures bt bf this character are extremely dangerous in time ai of freshel fre aliet fa 0 o any form foint oi construction it la Is doubtful whether the majority of practical road builders have given consideration ta the fact that by building suitable wing walls walla for any bridge or of p pipe they dan can very largely increase its its carrying capacity r A V on en trance why way so increases the velocity of bf the water as lo 10 enable a given con dult dull to perform the work of one of much larger firger diameter which has an ind end wall at right angles to the how flow |