Qiao Wang, Weiguo Song, Jun Zhang, and Siuming Lo
Foraging and nest relocation forming a bi-directional traffic of outbound and inbound individuals in one-lane organization are two main activities in ants’ life. In this paper, we conducted an experiment for nest relocation of loaded and unloaded ants, and some of them move back and forth between the old nest and the new one. In the experiment, we observed both uni- and bi-directional traffic flows of ants. The headway-speed relations indicate that the ants show the same sensitivity to the distance headway in both types of flows. For bi-directional traffic flow, head-on encounters and giving way behavior between opposite ants are common occurrence. It takes one unloaded ant 2.61 s to solve a head-on encounter with other unloaded one. Compared with unloaded ants, loaded ants have smaller moving speed, but are less likely to be impacted by head-on encounter. In observation region, both sudden stop and head-on encounter contained two phases, i.e. deceleration and acceleration were observed. Our analysis indicates that the relaxation time in deceleration process is less than that in acceleration process. The reduction of movement efficiency of encountering two discontinuous ants is larger than encountering two successive ants 0.18. This is owing to the absence of head-on encounter with following ants. Generally, this study investigates the bi-directional traffic of ants in experimental condition mainly and might inform the future studies of high-efficiency movement of collective behavior and traffic systems.