I think alleviating (not solving) Dhaka's traffic congestion requires four enforcement rules. First, the left lane must be kept free for vehicles turning left; and all other vehicles going straight or going right must not block the left lanes. Second, parking, especially on side/narrow roads, must not be allowed on either side of the street. Street signs must be put up to let vehicles know on which side they are allowed to park (if at all).
Third, vehicles must not occupy the centre of any intersection, restricting flow in the active lanes. Note how far the traffic edges forward into the intersections at Manik Mia Avenue and Mirpur Road or Mohakhali and Airport Road. And finally, dropping off passengers in the middle of the road poses life hazards and must be stopped immediately (for example,at the flyover near Shaheen School).
One or two traffic police officer at an intersection cannot alone enforce the above changes. These officials are often ignored. Soit would be best tohave teams of 10-15 roaming traffic enforcers pick up random traffic intersections at random times of the day to enforce the above. Penalties must be severe to deter violations.