Abstract: A modular crossing system generally includes a set of modules and a set of segments (e.g., bridge segments). Each segment includes a subset of the set of modules, and at least a portion of the set of segments are configured to be rotateably interlocked with a subsequent segment such that the set of segments form a crossing assembly having a deployed state and a collapsed state. Each module of the set of modules may include a hinge pin opening configured to removeably accept one of the set of hinge pins. The set of segments may be rotateably interlocked via the set of hinge pins.

Abstract: A payload adapter consists of a body that when hollow includes a plurality of stiffeners—radial and/or circumferential—or alternatively a core for carrying shear loads. The body may include a first annular face sheet, a second annular face sheet and a plurality of stiffeners connecting between the first annular face sheet and the second annular face sheet. The combination of the annular hollow body and the plurality of stiffeners or the same face sheets combined with an in-filled core results in an axial frequency and a lateral (pitch) frequency for the payload adapter that provides superior vibration isolation. Constrained layer damping is incorporated into the design for additional vibration attenuation.