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Brown County hears pitch for inflatable "balloon" bridge technology and discusses pilot of up to 10 spans
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Summary
County commissioners heard a presentation from a Dutch company about an inflatable-form concrete arch method the company says can cut material and construction costs, and discussed an initial site visit and engineer review for a pilot of up to 10 bridges.
County commissioners on April 27 heard a detailed presentation about an alternative bridge construction method that uses an inflatable form—described by the presenters as a balloon—to cast thin, monolithic concrete arched bridge shells. The company representatives said the technology reduces steel needs, shortens construction time and could be cheaper than conventional steel-girder bridges on short and medium spans.
A county consultant introduced the idea as a potential tool for rapidly replacing aging local bridges. One presenter said the method generates a 4–5 inch-thick concrete arch using an inflatable form that holds the shape while concrete is sprayed and cures; once the shell sets, crews deflate and remove the balloon and may reuse it for later pours. The presenter said a single inflatable form could be usable for roughly 10 bridges and that the approach could lower construction downtime because cured concrete can be ready in days rather than weeks.
On costs, the presenters gave a target construction range of about $100,000–$125,000 per bridge for the kinds of 50–55 foot spans discussed and said that, depending on project specifics, overall build costs might be about 20–25% less than traditional steel-girder methods. They emphasized that the method still requires engineering review and local code approvals and that an engineering stamp and KDOT (Kansas Department of Transportation) compliance would be necessary before any pilot.
Commissioners pressed the presenters on technical details including footings, foundation depth, reuse of the inflatable form and applicable mix design. Staff told the commission the next reasonable steps would be an initial site visit to identify candidate bridges, then local engineering review (staff referenced engineers in Manhattan and Wichita who could evaluate structural compliance). The consultant suggested identifying up to 10 candidate bridges for a phased pilot over 4–5 years rather than committing to an immediate construction contract.
The presenter said they had filmed completed examples in their home country and were prepared to provide additional technical materials and a site visit. Commissioners asked staff to arrange follow-up questions and an on-site inspection, and the commission signaled interest in receiving a more detailed scope and preliminary costs before any commitment.
What happens next: staff and the vendor will coordinate an initial site visit and engineer review; commissioners asked for more cost and compliance detail to be returned at a future meeting before any pilot is authorized.
