Gridlocking, also known as traffic jamming, is a common problem in big cities around the world. It refers to the situation when vehicles are unable to move due to heavy traffic congestion. To describe the opposite situation, we can use words such as "smoothflowing", "unimpeded", "unobstructed", and "free-flowing". These words suggest that traffic is moving easily and without any difficulties. Another possible antonym for "gridlocking" is "fluidity", which refers to the ability of traffic to move smoothly and efficiently. In contrast to gridlocking, fluidity indicates that there is space for vehicles to move and the traffic is not tightly packed.