Overflow Duct

Overflow Duct is an item-routing building used to divert and dispose of surplus items when a conveyor line in front of it becomes blocked. It does not pull or consume items actively; instead, it reacts to blockage on its forward-facing output by releasing stored throughput to its two lateral outputs. This behavior makes the Overflow Duct a passive overflow-management component rather than a regular splitter or router.

The core function of the Overflow Duct is to prevent backlogs on supply lines: when the tile directly in front of the duct is unable to accept more items, the duct will send those items out to its left and right sides. Because it only redirects items under the specific condition of a front blockage, it is best used where occasional saturation is expected and you want a deterministic way to route excess materials away from critical lines without interrupting normal flow. The duct does not consume power or items.

Practical usage and placements:

• Place the Overflow Duct at the end of a conveyor or before a bottleneck (such as a full container or factory) so that when the forward tile is full it automatically sends overflow to the sides.
• Use it to protect main supply arteries by connecting side chutes to storage, secondary processors, or disposal systems; this keeps essential production lines free from interruption.
• Because the duct only activates when the front is blocked, it will not interfere with normal throughput while the forward path is clear — it functions as an emergency bypass.
• The Overflow Duct requires no energy or item input to operate and therefore has no ongoing consumption cost.
• Upgrades: the duct can be enhanced with the overdrive-style upgrade listed in the source (noted as 超速（双科）), which increases its throughput behavior under the applicable upgrade mechanics. Apply upgrades according to available tech paths to improve handling of high-volume surges.

Design considerations:

• Combine Overflow Ducts with sorting or filtering devices if you need to redirect specific item types when overflow occurs.
• Be mindful that items sent sideways will follow the same conveyor rules; ensure side outputs have a destination or buffering to avoid creating new blockages.
• Because the duct only triggers on front blockage, deliberate testing under load is useful to verify the overflow routes behave as intended in complex networks.