A Competitive Short Span Steel Railway Bridge Concept [B3] 2025

AISC/NSBA, in conjunction with the American Association of Railways (AAR), recently designed and constructed a prototype short span steel railroad concept. This session covers the design, fabrication, and installation of a new concept for short-span steel railway bridges. This high-efficiency design includes hot-rolled, wide-flange shapes as main beams and simplified details that improve the fatigue performance of the span and reduce its capital cost of installation. In addition, the simplified details are anticipated to reduce the span’s cost of ownership through reduced complexity of inspections and reduced need for maintenance.

Structurally, the span exceeds all performance recommendations established by Chapter 15, “Steel Structures,” in the Manual for Railway Engineering published by the American Railway Engineering and Maintenance-of-Way Association (AREMA).

The span is installed as part of the Facility for Accelerated Service Testing (FAST) near Pueblo, Colorado. FAST is a full-scale railway proving ground operated by MxV Rail—a wholly owned subsidiary of the Association of American Railroads (AAR). FAST comprises a 2.8-mile loop of track within which any railway component or system, including railway bridge spans, can be tested under train live loading. The train loading at FAST generally comprises three six-axle radial-truck locomotives (400 kips each) and more than 110 open-top hopper cars loaded to 315 kips each. This loading is 10% more than the 286-kip maximum car weight defined by AAR rules for railcar interchange in North America. Each lap of this train results in an application of 0.018 million gross tons (MGT) of heavy axle loads.

Speaker(s): Gary Fry, Nick Marianos, Anthony Peterson