Final answer:
The height of the upper side impact structure for the artwork 'Intersection II' by Stephen Hill is 4 meters.
Step-by-step explanation:
The question appears to be related to the specifications of an art installation rather than a regulation requirement for vehicles or architecture, which might also reference 'upper side impact structures.' In particular, the question seems to refer to an artwork named Intersection II by Stephen Hill. According to the provided information, this sculpture consists of four identical conical sections and is constructed from weatherproof steel. The height requirement, or height specification, of the upper side impact structure for this specific art piece is 4 meters high.