  Lane-free vehicle movement has been recently proposed for connected automated
vehicles (CAV) due to various potential advantages. One such advantage stems
from the fact that incremental changes of the road width in lane-free traffic
lead to corresponding incremental changes of the traffic flow capacity. Based
on this property, the concept of internal boundary control was recently
introduced to flexibly share the total road width and capacity among the two
traffic directions of a highway in real-time, in response to the prevailing
traffic conditions, so as to maximize the cross-road (both directions)
infrastructure utilization. Feedback-based Linear-Quadratic regulators with or
without Integral action (LQI and LQ regulators) are appropriately developed in
this paper to efficiently address the internal boundary control problem.
Simulation investigations, involving a realistic highway stretch and different
demand scenarios, demonstrate that the proposed simple regulators are robust
and similarly efficient as an open-loop nonlinear constrained optimal control
solution, while circumventing the need for accurate modelling and external
demand prediction
