Most automatic bollard listings don't mention overlap length. That's not an accident.

The overlap is the section where the rising inner tube fits inside the fixed outer sleeve. When a vehicle strikes a bollard, the force isn't just pushing down — it's pushing sideways. The overlap zone is what resists that lateral load.

A short overlap acts like a short lever. The force applied at the top of the bollard is transmitted to a narrow contact band between the inner and outer tube. That band wears quickly. Under repeated impacts or even minor daily knocks, the inner tube starts to wobble, then bind, then fail.

A 20cm overlap distributes the same lateral force across a much longer contact surface. The load per unit area drops. Wear is slower. The bollard keeps operating cleanly for years instead of months.

UPARK bollards are built to a 20cm overlap specification. It's not a premium feature — it's a baseline requirement for a bollard that's supposed to function as vehicle access control infrastructure, not a decoration that fails when tested.

When comparing bollard options, ask the supplier for the overlap length. Many won't have the number ready. That gap in product knowledge usually reflects a gap in the product.

Full structural specifications for UPARK automatic bollards are available for direct comparison.