On a one-way urban road without lane markings, car drivers must **drive in the right lane**. This is because, in the absence of lines separating the lanes, the general rule is that all drivers must keep to the right. This rule ensures a more orderly and safer traffic flow.

However, it is allowed to use other lanes when circumstances advise it, such as when changing direction, overtaking another vehicle, or avoiding an obstacle. This flexibility is important to adapt to specific situations on the road.


In summary, driving in the right lane is the basic rule, but you can change lanes when necessary to maneuver safely and efficiently.