We recently discovered another stone arch bridge in Butler County, Kansas, that is located on the Towanda/Augusta township line. This culvert is located on 60th Street, just west of 60th’s intersection with Buffalo Road. This culvert is basic enough, but has one major peculiarity: It features a Gothic pointed segmental arch.
Pointed segmental arches are commonly associated with medieval times and not with Kansas culverts! The choice of this arch type in such a little culvert would hardly be for aesthetic reasons and overall seems a bit peculiar.
The obvious explanation of some kind of shifting of the stones resulting in arch distortion does not work here; the stones are all obviously roughly shaped into their current configuration, and a distinct triangular keystone is visible at the top; no sign of distortion can be seen. Sometimes if the mason made an error in arch design it is possible for there to be a mostly superficial peculiarity in shape at one of the arch faces.
This possibility, however, does not hold, as a look into the culvert shows a distinct Gothic point all the way through the width of the original stone structure.
A close look at the photo looking through the culvert does reveal one interesting feature. It would appear that the Gothic point is less pronounced at the far end of the culvert than at the front. Another interesting fact to note is that the keystones themselves do not always quite sit at the same level as the rest of the arch stones. This suggests that the keystones were rough-cut and then pounded into place with a hammer.
A Possible Explanation for the Shape
Overall, it seems as though the Gothic arch shape was sort of an accident rather than planned. It appears the pointed segmental arch was the result of the mason’s crude attempt at turning the arch. A close look at the arch face shows the curves are not entirely smooth. Also, on the right-hand side the first arch stone is placed up on an angle like a skewback, while there is no such clear feature on the left-hand side of the arch. Since the angles were not perfectly smooth around the curve, it necessitated the use of a triangular keystone at the top to close the arch tightly. It is a common fact when building Roman arches or segmental arches that if the angles on the lower courses of the arch are too shallow, the arch will need to be closed with a triangular keystone to complete the entire curve, resulting in a subtle Gothic appearance.
It seems probable that this bridge was intended as a Roman arch, but the crude techniques used to turn the arch resulted in the Gothic arch, which, incidentally, is easier to turn than a Roman arch. However, all this is not to be construed to mean that the mason who built this Butler stone bridge was a poor one; on the contrary, heavy shimming (some of the shims can be seen partly sticking out between arch stones) and rough-cutting of the stones combined to make this a durable culvert showing no signs of structural problems, despite the fact that much to all of the mortar is long gone.
The 60th Street stone culvert is an excellent and unique structure. It has been widened twice; the original north-side stone section is fairly narrow. Some sort of concrete structure comprises the middle section, while a typical corrugated metal culvert comprises the south section. The structure is in good condition overall, despite a few stones having been knocked from the spandrel walls. It looks like it could remain for ages, and, though the builder is unknown, it is clear that the builder took pains to ensure the bridge will last. For those visiting the culvert, be aware that it is not at all an obvious one, and is rather easy to miss. It is not far west of 60th’s intersection with Buffalo Road, and is near a deep ravine paralleling the road on the north side.