Bidding inside the identification of bid-rigging:
1, bidding documents are identical, such as the same format, the same font, the same table color.
2, bidding documents, errors in the same place.
3, electronic bidding, different bidders bidding registration of the same IP address, or IP address in a particular region.
4. Bidding documents of different bidders are prepared by the same computer or printed by the same attached equipment.
5, the binding form, thickness, cover, etc. of the bidding documents are similar or even the same.
6, a bidder's bidding documents, bound documents and materials of another bidder's name, for example: the appearance of another legal representative or authorized agent signature, stamped with the official seal of another bidder.
Collusive bidding
It is collusive bidding in addition to bid-rigging, i.e., general collusive bidding behavior that excludes the phenomenon of bid-rigging, including collusive bidding between bidders and bidders/bidding agents and loose-type non-legitimate collusive bidding by two or more bidders (i.e., not up to the intensity of manipulation and influence of bid-rigging). Narrowly defined collusive bidding and bid-rigging in a parallel relationship is the same as the two types of collusive bidding, that is, bid-rigging plus general collusive bidding is equal to the broader collusive bidding, usually referred to as collusive bidding can be interpreted as narrowly defined collusive bidding.
Reference: Baidu Encyclopedia - bid-rigging