146 



THE IRRIGATION AGE. 



ROAD CULVERTS AND SIPHONS. 

 By James Wharton Jones. 



There are three essentials which go to make 

 the ideal culvert: Strength, convenience, perma- 

 nence; and a form of construction which gives one 

 of these is sometimes lacking in the others. 



A culvert must be strong enough to support 

 the dead weight of deep fills, as well as to sustain 

 the shocks and vibrations incident to heavy and 

 rapidly moving traffic. The need for better roads 

 is generally conceded, and projects for highway im- 

 provement are receiving popular support in all sec- 

 tions. The development of great irrigation projects 

 nearly always involves the building of permanent 

 roads. A good road must be perfectly drained. 

 The most direct routes must be followed, and it is 

 demanded that such natural obstacles as exist to 



Installing Pure Iron Culvert Under Tracks of Interurban Railway. 



make this difficult be overcome in the interest of 

 more economical transportation. Road construc- 

 tion should conform to twentieth century conditions, 

 and where heavy grades existed, cuts and fills must 

 be made. Culverts placed beneath deep fills must 

 be not only of sufficient strength to support them, 

 but should possess a flexibility which will permit of 

 their conforming to uncertain or shifting founda- 

 tions. 



Water courses previously accommodated by 

 open swales or gutters must be so handled as to 

 maintain a level or unbroken highway ; the old time 

 bumps and "thank-you-marms" are no longer toler- 

 ated. The culvert provided here must be one, not 

 only giving the maximum of strength in proportion 

 to the amount of material employed in its con- 

 struction, but must possess also a degree of resi- 

 liency which will enable it to endure when sub- 

 jected to the blows and crushing stress of swiftly 

 moving auto trucks and other vehicles, even if pro- 

 tected by a minimum of covering. 



Corrugated iron culverts possess all these re- 

 quirements. Iron sheets when corrugated become 

 immensely rigid, and, when formed into a circular 

 shape, the increase of strength over that of plain 

 sheets is enormous. In correct corrugated iron cul- 

 vert construction large rivets, closely spaced, are 

 used, and each sheet is interlocked one full corru- 

 gation at the joints. The joints being double thick- 

 ness, are therefore the strongest points in the pipe. 



The installation of culverts is at best no easy 

 task. Locations are often remote from rail points, 

 and the delivery of materials becomes of much im- 



portance. Freight charges on certain forms of con- 

 struction form a very considerable part of their 

 ultimate cost. Hauling, handling and assembling 

 of materials all help to run this cost up to a pro- 

 hibitive point. Failure on the part of shippers to 

 include all parts, not to mention damages or break- 

 age en route, often prevent the ready execution of 

 well laid plans, causing expensive and annoying 

 delays. 



The ideal culverts are those which can be 

 cheaply and easily transported and handled ; those 

 which are complete within themselves and require 

 the least amount of skill to place in position for 

 service. Since corrugated pipe possesses all these 

 advantages, it is not to be wondered at that it has 

 achieved a considerable popularity with the builders 

 of highways and railroads. 



This material is also especially well adapted 

 for use in the form of inverted siphons. It is a 

 curious fact that a corrugated pipe is easier to keep 

 free from mud and other obstructions than one made 

 of smooth metal or masonry. The necessity for 

 these depressed crossings arises very frequently in 

 the irrigated regions, where it is very often the case 

 that highway drainage must be carried underneath 

 a canal or lateral or vice versa. 



While the first essential requirement in culvert 

 construction is strength, closely followed by need 

 for convenience in handling and placing, the final 

 requisite is that culverts shall be lasting. In con- 

 sidering this feature it should be borne in mind 

 that other factors than the mere disintegration of 

 materials often have to do with the life of a culvert. 

 There are precious few culverts in existence which 

 have served for a period of fifteen years. Wooden 

 structures warp and either wear or rot out in a 

 brief space of time, and their further use in culvert 

 construction is almost universally discredited. Brit- 

 tle materials crack and collapse with resulting ex- 

 pense of renewal or replacement. Breakage may 

 result from shocks of travel or shifting foundation 

 resulting from settling of earth or washouts. The 

 action of alkali soil, frost and other conditions is 

 often such as to ruin in a short period construc- 

 tion which was originally intended to last for all 

 time. 



Change of drainage frequently makes the re- 

 moval of a culvert necessary in order that provision 

 for increased flow may be made, and to accomplish 

 this the original culvert, if not removable, must be 

 destroyed. If a change of route occurs, such cul- 

 verts as are built into place from materials which 

 cannot be shifted, represent a total loss for further 

 service, and the permanence originally hoped for, 

 does not exist. 



High-purity iron corrugated culverts represent 

 a very permanent type of culvert construction. 

 When built from the proper gauges they are not 

 harmed by heavy or shallow fills, and because of 

 their flexibility, will not crack or break down as 

 a result of shifting foundations. They do not wash 

 out because the earth in which they are placed 

 packs into their corrugations, and prevents the be- 

 ginning of trickling streams of water along their 

 sides. 



They are removable at will, and can be used 

 again and again. Their permanence is therefore 

 (Continued on page 151.) 



