Palisade fencing
Steel palisade is a visible deterrent. Where a site needs to look genuinely difficult to enter, it does that job better than almost anything else at the same price.
Pale profiles and tops
Pales come in D and W profiles — W is stiffer and harder to bend. Tops can be rounded, single-pointed or triple-pointed depending on how strong a deterrent is appropriate for the setting.
Fixings should be anti-tamper, because a palisade fence with standard bolts can be dismantled from outside.
Finish and durability
Galvanised as standard, powder coated where appearance matters. Both hold up well in an urban environment with no ongoing maintenance beyond occasional inspection.