Seating for spectators/audiences at sports, music and other events. Arrives as a container/trailer on a lorry.
Has a small, self-contained power and control unit. Place it in the right location, clear the area, and press the go button.
Electrohydraulically it unfolds, like an electrohydraulic butterfly. Foot-pads spread to stably distribute load on soft grounds. A bank of seats slides out vertically and horizontally to form an audience stand, with steps, aisles and handrails already integrated.
Optional extras: canopy/sunshade, lighting & power distribution, sound system, portaloos underneath. Perhaps powered wheels to manoeuvre/hitch to trailer.
Multiple units can be connected along/around to form complete stadia.
When the events over, press the close button (making sure no-one is still in the stand) and it folds, concertinas and compresses itself back into its container unit.-- Frankx, Sep 30 2019 //Self-erecting Spectator Seating// I'm not going to any event where the spectators are self-erecting, thankyouverymuch.-- MaxwellBuchanan, Sep 30 2019 This already exists. We have observed several being set up at a motorsport event. They were built on standard articulated truck trailers; after the tractor units were uncoupled, a pipe or cable was run back to power the deployment. We suspect the mechanism was electrical but could have been hydraulic; probably not pneumatic as air motors are distinctively noisy.-- 8th of 7, Sep 30 2019 Thanks both. Provisionally [mfd], but ill let it remain for a moment (if you dont mind) while I find a source.-- Frankx, Sep 30 2019 random, halfbakery