Stone Arch Bridges

Walter Sharp, famous for building the stone arch bridges of Cowley County, Kansas, wrote extensively on the topic. In this post, we quote an article by Walter Sharp describing how he built stone bridges. This article was written to the Kansas State Engineer to advocate for a stone arch bridge near Cambridge. This design was not approved, but in Sharp’s letter he describes in some detail various aspects of the methods commonly used to build Cowley’s stone arch bridges.

Building the Bridges

“Now getting back to the stone arch bridge; these are not my plans, but the plans our old County Engineer and our County Board. A pencil scratch of these plans was handed Mr. Ruggles by our County Board some two months ago to be considered in the bridge letting; hence Mr. Ruggles or the State Engineer’s office isn’t turning me down, but our County board, if you should turn the plans down.

“Mr. Ruggles gives five reasons why he cannot recommend the plans.

“No. 1 — He does not consider the water way adequate. The new bridge is to take the place of a 70-foot steel bridge that has been there 30 years, and has given perfect satisfaction as to water way. The county’s plan for stone arch is 120 feet waterway, as you can see by referring to the plans. There are 14 stone arches on Grouse Creek, only one bridge, has larger waterway. Down the stream seven miles are to be found three stone arches. The first is a bridge of one 50 feet span and one 30 foot span. The next is [a] bridge of one span of 60 feet; this is the last stone bridge built by the county and this is the bridge the State Engineer’s office approved the plans for and by so doing said that sixty foot waterway was enough waterway for Grouse Creek and now I am asking you to approve plans for another stone arch for Grouse Creek five miles farther up stream with one hundred and twenty feet water way and a better bridge in every way, as you can see by comparing the plans which you have in your office. The third bridge is a seventy-five foot stone arch; said to be the largest single arch in Kansas. All the bridges above the proposed new bridge are stone arches. Three miles above is a bridge of 53 foot span, built 21 years ago. I have never heard of any complaint about waterway.

“Objection No. 2 says the piers are light. There are about 100 large stone arches in Cowley; all have been designed by Mr. Bradley. He figures all his plans so the line of pressure falls inside the abutment which is planned to rest on bed rock. No stone bridge has failed in this County on account of failure in the arch ring or thrust of the arch.

“Two bridges have failed however where pile foundation was depended on; none has failed that rested on bed rock.

“No. 3 — Spandrel walls too light. This Mr. Bradley has always taken care of by making the fill rock. No spandrel walls have failed in this county with stone fill.

“Objection No. 4 — Manner of grouting the arch instead of cutting to true radial lines.

“This is the secret of all the stone arch work in Cowley County as before stated I think there are about 100 stone arches from 20 to 75 feet every one a grouted arch ring. Had it not been for this I doubt if there would ever have been a stone arch of size and the county would be loaded down with a lot of old steel bridges to keep in repair and replace. Let me go into [detail] and tell you what a grouted arch ring means in Cowley. All over Cowley County, especially the eastern part, splendid ledges of rock crop out; these ledges range in thickness from 12 inches up to 36 inches. After the dirt is stripped off, these great slabs of rock lay there and are split with plug and feather into blocks that somewhat resemble a paving brick; the size would perhaps be 18 inches in thickness, 24 to 30 inches wide and from 4 to 8 feet long. These rock will be picked up by derricks from their bed, swung around [to] a convenient place to work on, putting the smoothest split side up. A man who has been shown how (not a stone cutter) takes his straight edge and tools and cuts a 2-inch margin on both sides of the up-turned face of the stone, squares both ends, cuts the sides to a line six inches back from the face and this arch stone is ready for its place in the arch ring. An ordinary 40 cents per hour man can do this in two to three hours. While a stone cutter costing $10 per day would put in a day and a half cutting this stone to a half inch joint and to radial lines. The outside or ring stone shows the radial lines, but all other sheeting stones are as shown. These stones are set on a two by four sheeting resting on arch centers. The mortar joint meeting in the center of 2×4 only that part of the stone have a 2-inch margin draft touch the 2-inch sheeting. These arch stones are bedded only three inches at time of laying (except ring stone). After all the arch ring is completed then the grouting takes place. Some of the openings are large enough to put your arm in, but all are filled with a grouting of one-two-four mixture. If you take this one feature away from the stone arch building of Cowley County then Cowley County will never have another stone arch of any size built in the county.

“Objection No. 5, of Mr. Ruggles’ letter says not enough provision has been made for wing walls to protect the fill. In making these plans Mr. Bradley took into account the very good stone in the abutments under the old steel bridge and left that for later consideration, thinking he could save the county some money by so doing.”

Walter Sharp, “Tyranny in Kansas Road Building,” The Wichita Eagle, September 8, 1922.

Comments on the Above Account

Mr. Ruggles, mentioned in the above account, was a new county engineer in Cowley at the time the article was written. Mr. Bradley was his predecessor, and is largely responsible for the design of most of Cowley’s larger stone bridges. For the locations of the bridges Walter Sharp mentions as being on Grouse Creek, please see, Cowley Grouse Creek Stone Arch Bridges Part 5: The Location of the Grouse Creek Stone Arch Bridges. The bridge described above was never approved, and the final structure was made of concrete. It was located roughly where US 160 crosses Grouse Creek near Cambridge.