Stone arches are frequently used for culverts in cases where the span is not great, and in which the design of the culvert (except for some small details regarding the wing walls) depends only on the span of the culvert. The design of some arch culverts used on the Atchison, Topeka & Santa Fe Railroad (see Fig. 76, and also Fig. 74) is copied from a paper presented to the American Society of Civil Engineers by A. G. Allan, Asso. Mem. Am. Soc C. E. The span of these arches is 14 feet, and the thickness at the crown is 18 inches. A photograph of one of these arch culverts, which shows also many other details, is reproduced in Fig. 77.