Such as a bridge?

(Rather than being used singly)

[CdM] doh!

[Software] Still unique? NO
[CdM] Can a person go inside? YES *some applause mixed with mutterings from the audience*
[FGZ] Other form of structure? YES *same mix of sounds from the audience again*
[INJ] Seen in groups? NO
[GL] Usually outside? YES *gentle applause*
[Software again] Bollards? NO

(CdM) Transference? Of course. But up to that point it fitted. :-)

[INJ] Industrial? NO
[Rosie] Shelter? NO
[irach] Shed/barn? NO

Possibly tower bridge?

[irach] Phone booth sized? NO
[FGZ] Bridge? NO

[Rosie] A tunnel? NO, but a tunnel might be incorporated.

Possibly the one that must not be mentioned as it would cause a game end sequence?

[GL] A sewer? NO
[FGZ] Tube station? NO *audience starts to lose interest*

[irach] high- or rail-way? NO

The words on the card relate to something that is Mineral, often with a little vegetable
Positives established are:

• The vegetable portion is wood
• It is manufactured
• bigger than a 4-slice toaster in all 3 dimensions
• primarily functional
• made of concrete
• A person can "go inside"
• some other kind of "structure" (other than building or statue/sculpture)
• Usually outside

Negatives established are:
No precious minerals; not naturally occurring; no accidental vegetable material; not a geographical feature; not a building, not unique; not a garden object; not made of stone; can't be picked up in one hand; not a signal; doesn't start with P; not a steam locomotive; not seen in groups; not a bollard; not industrial; not a shed/barn; not a shelter; not phone-box-sized; not a bridge; not a tunnel per se (but may incorporate a tunnel); not a sewer; not a tube station; not a highway nor a railway.

The audience were appreciative of it being outdoors, primarily functional and made of concrete. They were given to debate amongst themselves as to whether a person could go inside, or whether it was a form of structure. I am, however, confident of saying YES to both of these.