Even as the stone bridge era reached its peak in Kansas, stone began to be replaced with concrete.
Kansas Shifts to Concrete
Concrete was just beginning to come into its own at that time, and counties were opting for concrete where stone was not readily available. These early bridges built of concrete were designed exactly like the stone bridges they replaced.
Ironically, some of these early concrete bridges were still classed as “stone” bridges.
Around this time Walter Sharp introduced and patented a concrete slab bridge of his own design.
One advantage of a flattop concrete slab bridge is the unobstructed waterway. Obstructed waterways was always rather a problem with the stone arch bridges. Arch bridges usually were built with the arches “springing” from the low-water mark, resulting in a constricted waterway higher up in the water due to the narrowing of the arch.
Slab bridges eliminated this difficulty, though Walter Sharp’s concrete slab bridges proved to be poorly designed and fail-prone.
Trouble with Limestone Bridges
Another problem that was beginning to show up with stone bridges was the disintegration of the native limestone used. Where the limestone directly contacts the water it tends to disintegrate, resulting in eventual failure of the bridge.
While concrete could be used at the waterline to solve this problem (and was used in Butler County), the easy construction of concrete bridges had its appeal, and concrete began to replace stone in earnest in the 1910s.
The End of the Stone Arch Bridge Era
By 1915, Butler County declared they were going to quit building stone arch bridges, which they did with a few exceptions. Yet even before that time Butler was largely favoring concrete anyway.
Cowley County kept building with stone for a few more years, but eventually ran into trouble with the state needing to approve bridge plans. The state government favored concrete, but was willing to approve stone bridge plans. However, the state plans required stone bridges to be built at a higher quality than what Cowley (through Walter Sharp) typically used. Walter Sharp’s plans were economical, but declared to be poor quality by the state, the state engineer arguing that a concrete bridge of better quality could be built at the same price as the typical stone bridge built in this fashion. Cowley did, in fact, build one stone arch bridge as per the state’s plans, and this bridge cost more than any other county-built stone arch bridge, but was remarkably well built.
Kansas’s stone arch bridge glory years petered out in the 1910s, and came to a close in the 1920s.
The WPA Era: Stone Makes a Comeback
Stone arch bridges were destined to be built again in Kansas, however. With the introduction of the the Works Progress Administration (WPA), stone arch bridges began to be built across the state again.
The WPA bridges were very high-quality structures, featuring superb stonework and dual-lane width. Beginning in the mid-30s and continuing to about World War II, the WPA built a massive number of stone arch bridges in Kansas, particularly in the western counties.
As the WPA’s real goal was to create works projects, and not to achieve maximum economy, the greater expense of well-built stone arch bridges was no problem.
Stone Arch Bridges Today
After the WPA era the stone arch bridge era in Kansas came to a halt. Nevertheless, numerous relics of the bygone stone bridging days of Kansas remain across the state. Although sometimes modified and widened, most of these stone arch bridges still are actively used on Kansas’s roads.
As long as Kansas still has numerous stone arch bridges in active use, the stone arch bridge era of Kansas is not truly over.