Why does police make one-ways?

One ways are made to overcome limited width (carriage way) of the road and to avoid frequent hold ups for right turn. For two way, every time traffic has to turn right, there arises a need for junction signalized or otherwise. For every right turning traffic has to stop traffic from opposite direction. By making one way, not only width problem is eliminated but also traffic can turn left and right without stopping. As a result, traffic continues to move without stopping.
Contrary to the common perception, traffic police has not made any one way in past two years except for temporary purpose of metro or BBMP developmental works. In fact major roads have been made two ways like Sarjapur Road, Hosur Road, Palace Road etc. Widening and restrictions on right turns made it possible.